llvm-native-core 0.1.14

//! Builtin Header Definitions — compiler-provided standard library
//! headers.
//!
//! Clang ships builtin definitions for several standard C headers so
//! that a bare-metal or freestanding environment can compile standard
//! C programs without requiring a full C library installation.  The
//! definitions here match the behaviour of Clang's `lib/clang/*/include`
//! directory.
//!
//! Headers covered:
//! - `<stddef.h>`  — size_t, ptrdiff_t, NULL, offsetof, max_align_t,
//!   wchar_t, nullptr_t
//! - `<stdint.h>`  — exact-width integers, limits, size_max
//! - `<stdbool.h>` — bool, true, false
//! - `<stdarg.h>`  — va_list, va_start, va_arg, va_end, va_copy
//! - `<limits.h>`  — integer limits
//! - `<float.h>`   — floating-point characteristics
//! - `<iso646.h>`  — alternative operator spellings
//!
//! Additionally, compiler builtins for memory, type traits, overflow
//! arithmetic, and branch prediction hints are provided.
//!
//! Clean-room behavioural reconstruction from ISO C11/C17 and published
//! Clang documentation.  No LLVM/Clang source code is consulted.

use std::collections::HashMap;

// ═══════════════════════════════════════════════════════════════════════════
// Builtin Header Kind
// ═══════════════════════════════════════════════════════════════════════════

/// All builtin headers that the compiler can supply.
#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
pub enum BuiltinHeader {
    Stddef,
    Stdint,
    Stdbool,
    Stdarg,
    Limits,
    Float,
    Iso646,
    /// `<stdatomic.h>` — C11 atomics
    Stdatomic,
    /// `<stdalign.h>` — C11 alignas/alignof
    Stdalign,
    /// `<stdnoreturn.h>` — C11 noreturn
    Stdnoreturn,
    /// `<tgmath.h>` — type-generic math (stub)
    Tgmath,
    /// `<unwind.h>` — unwinding support
    Unwind,
    /// `<float.h>` extension: `<cfloat>` / `<float.h>` for C++
    Cfloat,
}

impl BuiltinHeader {
    /// The filename as it appears in `#include <...>`.
    pub fn filename(&self) -> &'static str {
        match self {
            Self::Stddef => "stddef.h",
            Self::Stdint => "stdint.h",
            Self::Stdbool => "stdbool.h",
            Self::Stdarg => "stdarg.h",
            Self::Limits => "limits.h",
            Self::Float => "float.h",
            Self::Iso646 => "iso646.h",
            Self::Stdatomic => "stdatomic.h",
            Self::Stdalign => "stdalign.h",
            Self::Stdnoreturn => "stdnoreturn.h",
            Self::Tgmath => "tgmath.h",
            Self::Unwind => "unwind.h",
            Self::Cfloat => "cfloat",
        }
    }

    /// Whether this header is standard in C89.
    pub fn is_c89(&self) -> bool {
        matches!(
            self,
            Self::Stddef | Self::Stdarg | Self::Limits | Self::Float
        )
    }

    /// Whether this header is standard in C99.
    pub fn is_c99(&self) -> bool {
        matches!(
            self,
            Self::Stddef
                | Self::Stdint
                | Self::Stdbool
                | Self::Stdarg
                | Self::Limits
                | Self::Float
                | Self::Iso646
                | Self::Tgmath
        )
    }

    /// Whether this header is standard in C11.
    pub fn is_c11(&self) -> bool {
        matches!(
            self,
            Self::Stddef
                | Self::Stdint
                | Self::Stdbool
                | Self::Stdarg
                | Self::Limits
                | Self::Float
                | Self::Iso646
                | Self::Stdatomic
                | Self::Stdalign
                | Self::Stdnoreturn
                | Self::Tgmath
        )
    }
}

// ═══════════════════════════════════════════════════════════════════════════
// Builtin Header Generator
// ═══════════════════════════════════════════════════════════════════════════

/// Generates the content of compiler-provided builtin headers.
///
/// The generator knows about the target's pointer width, endianness,
/// and other properties that influence header content (e.g.  whether
/// `long` is 32 or 64 bits, the size of `wchar_t`).
#[derive(Debug, Clone)]
pub struct BuiltinHeaderGenerator {
    /// Target pointer width in bits (32 or 64).
    pub pointer_width: u32,
    /// Target `long` width in bits.
    pub long_width: u32,
    /// Target `long long` width in bits.
    pub long_long_width: u32,
    /// Target `wchar_t` width in bits (16 on Windows, 32 on most Unix).
    pub wchar_width: u32,
    /// Whether the target is little-endian.
    pub little_endian: bool,
    /// Target `int` width in bits.
    pub int_width: u32,
    /// Target `short` width in bits.
    pub short_width: u32,
    /// Target `char` width in bits (typically 8).
    pub char_width: u32,
    /// Whether `char` is signed.
    pub char_is_signed: bool,
    /// Maximum alignment in bytes for the target.
    pub max_alignment: u32,
    /// Whether to emit `__int128` support.
    pub has_int128: bool,
}

impl BuiltinHeaderGenerator {
    /// Create a generator for a typical x86-64 Linux target.
    pub fn new_x86_64_linux() -> Self {
        Self {
            pointer_width: 64,
            long_width: 64,
            long_long_width: 64,
            wchar_width: 32,
            little_endian: true,
            int_width: 32,
            short_width: 16,
            char_width: 8,
            char_is_signed: true,
            max_alignment: 16,
            has_int128: true,
        }
    }

    /// Create a generator for a typical 32-bit ARM target.
    pub fn new_arm_linux() -> Self {
        Self {
            pointer_width: 32,
            long_width: 32,
            long_long_width: 64,
            wchar_width: 32,
            little_endian: true,
            int_width: 32,
            short_width: 16,
            char_width: 8,
            char_is_signed: false, // ARM AAPCS: char is unsigned
            max_alignment: 8,
            has_int128: false,
        }
    }

    /// Create a generator for a typical AArch64 target.
    pub fn new_aarch64_linux() -> Self {
        Self {
            pointer_width: 64,
            long_width: 64,
            long_long_width: 64,
            wchar_width: 32,
            little_endian: true,
            int_width: 32,
            short_width: 16,
            char_width: 8,
            char_is_signed: false,
            max_alignment: 16,
            has_int128: true,
        }
    }

    /// Create a generator for a 32-bit x86 target.
    pub fn new_x86_linux() -> Self {
        Self {
            pointer_width: 32,
            long_width: 32,
            long_long_width: 64,
            wchar_width: 32,
            little_endian: true,
            int_width: 32,
            short_width: 16,
            char_width: 8,
            char_is_signed: true,
            max_alignment: 16,
            has_int128: false,
        }
    }

    // ── Full header content ──────────────────────────────────────────────

    /// Generate the content of a given builtin header.
    pub fn generate(&self, header: BuiltinHeader) -> String {
        match header {
            BuiltinHeader::Stddef => self.generate_stddef(),
            BuiltinHeader::Stdint => self.generate_stdint(),
            BuiltinHeader::Stdbool => self.generate_stdbool(),
            BuiltinHeader::Stdarg => self.generate_stdarg(),
            BuiltinHeader::Limits => self.generate_limits(),
            BuiltinHeader::Float => self.generate_float(),
            BuiltinHeader::Iso646 => self.generate_iso646(),
            BuiltinHeader::Stdatomic => self.generate_stdatomic(),
            BuiltinHeader::Stdalign => self.generate_stdalign(),
            BuiltinHeader::Stdnoreturn => self.generate_stdnoreturn(),
            BuiltinHeader::Tgmath => self.generate_tgmath(),
            BuiltinHeader::Unwind => self.generate_unwind(),
            BuiltinHeader::Cfloat => self.generate_float(), // same as float.h
        }
    }

    /// Generate all builtin headers at once, returning a map
    /// from filename to content.
    pub fn generate_all(&self) -> HashMap<String, String> {
        let mut map = HashMap::new();
        let all = [
            BuiltinHeader::Stddef,
            BuiltinHeader::Stdint,
            BuiltinHeader::Stdbool,
            BuiltinHeader::Stdarg,
            BuiltinHeader::Limits,
            BuiltinHeader::Float,
            BuiltinHeader::Iso646,
            BuiltinHeader::Stdatomic,
            BuiltinHeader::Stdalign,
            BuiltinHeader::Stdnoreturn,
            BuiltinHeader::Tgmath,
        ];
        for h in &all {
            map.insert(h.filename().to_string(), self.generate(*h));
        }
        map
    }

    // ── <stddef.h> ───────────────────────────────────────────────────────

    fn generate_stddef(&self) -> String {
        let mut s = String::new();

        // Include guard
        s.push_str("#ifndef __STDDEF_H\n");
        s.push_str("#define __STDDEF_H\n\n");

        // ── Common definitions ────────────────────────────────────────
        s.push_str("#if defined(__need_size_t) || defined(__need_ptrdiff_t) \\\n");
        s.push_str("    || defined(__need_wchar_t) || defined(__need_NULL) \\\n");
        s.push_str("    || defined(__need_max_align_t) || !defined(__STDDEF_H)\n");
        s.push_str("#define __STDDEF_H\n\n");

        // size_t
        s.push_str("#if !defined(__size_t_defined)\n");
        s.push_str("#define __size_t_defined\n");
        if self.pointer_width == 64 {
            s.push_str("typedef unsigned long size_t;\n");
        } else {
            s.push_str("typedef unsigned int size_t;\n");
        }
        s.push_str("#endif\n\n");

        // ptrdiff_t
        s.push_str("#if !defined(__ptrdiff_t_defined)\n");
        s.push_str("#define __ptrdiff_t_defined\n");
        if self.pointer_width == 64 {
            s.push_str("typedef long ptrdiff_t;\n");
        } else {
            s.push_str("typedef int ptrdiff_t;\n");
        }
        s.push_str("#endif\n\n");

        // NULL
        s.push_str("#if !defined(NULL)\n");
        s.push_str("#if defined(__cplusplus)\n");
        s.push_str("#if __cplusplus >= 201103L\n");
        s.push_str("#define NULL nullptr\n");
        s.push_str("#else\n");
        s.push_str("#define NULL 0\n");
        s.push_str("#endif\n");
        s.push_str("#else\n");
        s.push_str("#define NULL ((void*)0)\n");
        s.push_str("#endif\n");
        s.push_str("#endif\n\n");

        // offsetof
        s.push_str("#if !defined(offsetof)\n");
        s.push_str("#define offsetof(type, member) ");
        s.push_str("__builtin_offsetof(type, member)\n");
        s.push_str("#endif\n\n");

        // max_align_t
        s.push_str("#if !defined(__max_align_t_defined)\n");
        s.push_str("#define __max_align_t_defined\n");
        s.push_str("typedef struct {\n");
        if self.max_alignment >= 16 {
            s.push_str("  long long __max_align_ll __attribute__((__aligned__(__alignof__(long long))));\n");
            s.push_str("  long double __max_align_ld __attribute__((__aligned__(__alignof__(long double))));\n");
        } else if self.max_alignment >= 8 {
            s.push_str("  long long __max_align_ll __attribute__((__aligned__(__alignof__(long long))));\n");
            s.push_str(
                "  double __max_align_d __attribute__((__aligned__(__alignof__(double))));\n",
            );
        } else {
            s.push_str("  long __max_align_l __attribute__((__aligned__(__alignof__(long))));\n");
            s.push_str(
                "  double __max_align_d __attribute__((__aligned__(__alignof__(double))));\n",
            );
        }
        s.push_str("} max_align_t;\n");
        s.push_str("#endif\n\n");

        // wchar_t
        s.push_str("#if !defined(__wchar_t_defined)\n");
        s.push_str("#define __wchar_t_defined\n");
        if self.wchar_width == 16 {
            s.push_str("#ifndef __cplusplus\n");
            s.push_str("typedef unsigned short wchar_t;\n");
            s.push_str("#endif\n");
        } else {
            s.push_str("#ifndef __cplusplus\n");
            s.push_str("typedef int wchar_t;\n");
            s.push_str("#endif\n");
        }
        s.push_str("#endif\n\n");

        // nullptr_t (C23, C++11)
        s.push_str("#if !defined(__nullptr_t_defined)\n");
        s.push_str("#define __nullptr_t_defined\n");
        s.push_str("#if defined(__cplusplus) && __cplusplus >= 201103L\n");
        s.push_str("typedef decltype(nullptr) nullptr_t;\n");
        s.push_str("#elif defined(__STDC_VERSION__) && __STDC_VERSION__ >= 202311L\n");
        s.push_str("typedef typeof(nullptr) nullptr_t;\n");
        s.push_str("#endif\n");
        s.push_str("#endif\n\n");

        // unreachable (C23)
        s.push_str("#if !defined(unreachable)\n");
        s.push_str("#define unreachable() __builtin_unreachable()\n");
        s.push_str("#endif\n\n");

        s.push_str("#endif /* __STDDEF_H */\n");
        s
    }

    // ── <stdint.h> ───────────────────────────────────────────────────────

    fn generate_stdint(&self) -> String {
        let mut s = String::new();

        s.push_str("#ifndef __STDINT_H\n");
        s.push_str("#define __STDINT_H\n\n");

        // Include limits for integer widths if needed
        s.push_str("#ifndef __INT_WIDTH_STANDARD\n");
        s.push_str("#define __INT_WIDTH_STANDARD\n");
        s.push_str("#define __INT8_WIDTH__ 8\n");
        s.push_str("#define __INT16_WIDTH__ 16\n");
        s.push_str("#define __INT32_WIDTH__ 32\n");
        s.push_str("#define __INT64_WIDTH__ 64\n");
        s.push_str("#endif\n\n");

        // ── Exact-width integers ───────────────────────────────────────
        s.push_str("/* Exact-width integer types */\n");
        s.push_str("typedef signed char      int8_t;\n");
        s.push_str("typedef short            int16_t;\n");
        s.push_str("typedef int              int32_t;\n");
        if self.has_int128 {
            s.push_str("typedef long             int64_t;\n");
            s.push_str("#ifdef __SIZEOF_INT128__\n");
            s.push_str("typedef __int128          int128_t;\n");
            s.push_str("#endif\n");
        } else {
            s.push_str("typedef long long        int64_t;\n");
        }
        s.push_str("\n");
        s.push_str("typedef unsigned char      uint8_t;\n");
        s.push_str("typedef unsigned short     uint16_t;\n");
        s.push_str("typedef unsigned int       uint32_t;\n");
        if self.has_int128 {
            s.push_str("typedef unsigned long      uint64_t;\n");
            s.push_str("#ifdef __SIZEOF_INT128__\n");
            s.push_str("typedef unsigned __int128  uint128_t;\n");
            s.push_str("#endif\n");
        } else {
            s.push_str("typedef unsigned long long uint64_t;\n");
        }
        s.push_str("\n");

        // ── Minimum-width integers ─────────────────────────────────────
        s.push_str("/* Minimum-width integer types */\n");
        s.push_str("typedef signed char       int_least8_t;\n");
        s.push_str("typedef short             int_least16_t;\n");
        s.push_str("typedef int               int_least32_t;\n");
        if self.long_width >= 64 {
            s.push_str("typedef long              int_least64_t;\n");
        } else {
            s.push_str("typedef long long         int_least64_t;\n");
        }
        s.push_str("\n");
        s.push_str("typedef unsigned char      uint_least8_t;\n");
        s.push_str("typedef unsigned short     uint_least16_t;\n");
        s.push_str("typedef unsigned int       uint_least32_t;\n");
        if self.long_width >= 64 {
            s.push_str("typedef unsigned long      uint_least64_t;\n");
        } else {
            s.push_str("typedef unsigned long long uint_least64_t;\n");
        }
        s.push_str("\n");

        // ── Fastest minimum-width integers ─────────────────────────────
        s.push_str("/* Fastest minimum-width integer types */\n");
        s.push_str("typedef signed char       int_fast8_t;\n");
        s.push_str("typedef int               int_fast16_t;\n");
        s.push_str("typedef int               int_fast32_t;\n");
        if self.pointer_width == 64 {
            s.push_str("typedef long              int_fast64_t;\n");
        } else {
            s.push_str("typedef long long         int_fast64_t;\n");
        }
        s.push_str("\n");
        s.push_str("typedef unsigned char      uint_fast8_t;\n");
        s.push_str("typedef unsigned int       uint_fast16_t;\n");
        s.push_str("typedef unsigned int       uint_fast32_t;\n");
        if self.pointer_width == 64 {
            s.push_str("typedef unsigned long      uint_fast64_t;\n");
        } else {
            s.push_str("typedef unsigned long long uint_fast64_t;\n");
        }
        s.push_str("\n");

        // ── Pointer-sized integers ─────────────────────────────────────
        s.push_str("/* Integer types capable of holding object pointers */\n");
        if self.pointer_width == 64 {
            s.push_str("typedef long              intptr_t;\n");
            s.push_str("typedef unsigned long     uintptr_t;\n");
        } else {
            s.push_str("typedef int               intptr_t;\n");
            s.push_str("typedef unsigned int      uintptr_t;\n");
        }
        s.push_str("\n");

        // ── Greatest-width integers ────────────────────────────────────
        s.push_str("/* Greatest-width integer types */\n");
        if self.has_int128 {
            s.push_str("#ifdef __SIZEOF_INT128__\n");
            s.push_str("typedef __int128          intmax_t;\n");
            s.push_str("typedef unsigned __int128 uintmax_t;\n");
            s.push_str("#else\n");
            s.push_str("typedef long long         intmax_t;\n");
            s.push_str("typedef unsigned long long uintmax_t;\n");
            s.push_str("#endif\n");
        } else {
            s.push_str("typedef long long         intmax_t;\n");
            s.push_str("typedef unsigned long long uintmax_t;\n");
        }
        s.push_str("\n");

        // ── Limits of exact-width integers ─────────────────────────────
        s.push_str("/* Limits of exact-width integer types */\n");
        s.push_str("#define INT8_MIN   (-128)\n");
        s.push_str("#define INT8_MAX   (127)\n");
        s.push_str("#define UINT8_MAX  (255)\n\n");

        s.push_str("#define INT16_MIN  (-32768)\n");
        s.push_str("#define INT16_MAX  (32767)\n");
        s.push_str("#define UINT16_MAX (65535)\n\n");

        s.push_str("#define INT32_MIN  (-2147483647 - 1)\n");
        s.push_str("#define INT32_MAX  (2147483647)\n");
        s.push_str("#define UINT32_MAX (4294967295U)\n\n");

        if self.long_width >= 64 {
            s.push_str("#define INT64_MIN  (-9223372036854775807L - 1L)\n");
            s.push_str("#define INT64_MAX  (9223372036854775807L)\n");
            s.push_str("#define UINT64_MAX (18446744073709551615UL)\n\n");
        } else {
            s.push_str("#define INT64_MIN  (-9223372036854775807LL - 1LL)\n");
            s.push_str("#define INT64_MAX  (9223372036854775807LL)\n");
            s.push_str("#define UINT64_MAX (18446744073709551615ULL)\n\n");
        }

        // ── Limits of minimum-width integers ───────────────────────────
        s.push_str("/* Limits of minimum-width integer types */\n");
        s.push_str("#define INT_LEAST8_MIN   INT8_MIN\n");
        s.push_str("#define INT_LEAST8_MAX   INT8_MAX\n");
        s.push_str("#define UINT_LEAST8_MAX  UINT8_MAX\n\n");

        s.push_str("#define INT_LEAST16_MIN  INT16_MIN\n");
        s.push_str("#define INT_LEAST16_MAX  INT16_MAX\n");
        s.push_str("#define UINT_LEAST16_MAX UINT16_MAX\n\n");

        s.push_str("#define INT_LEAST32_MIN  INT32_MIN\n");
        s.push_str("#define INT_LEAST32_MAX  INT32_MAX\n");
        s.push_str("#define UINT_LEAST32_MAX UINT32_MAX\n\n");

        s.push_str("#define INT_LEAST64_MIN  INT64_MIN\n");
        s.push_str("#define INT_LEAST64_MAX  INT64_MAX\n");
        s.push_str("#define UINT_LEAST64_MAX UINT64_MAX\n\n");

        // ── Limits of fastest minimum-width integers ───────────────────
        s.push_str("/* Limits of fastest minimum-width integer types */\n");
        s.push_str("#define INT_FAST8_MIN   INT8_MIN\n");
        s.push_str("#define INT_FAST8_MAX   INT8_MAX\n");
        s.push_str("#define UINT_FAST8_MAX  UINT8_MAX\n\n");

        s.push_str("#define INT_FAST16_MIN  INT32_MIN\n");
        s.push_str("#define INT_FAST16_MAX  INT32_MAX\n");
        s.push_str("#define UINT_FAST16_MAX UINT32_MAX\n\n");

        s.push_str("#define INT_FAST32_MIN  INT32_MIN\n");
        s.push_str("#define INT_FAST32_MAX  INT32_MAX\n");
        s.push_str("#define UINT_FAST32_MAX UINT32_MAX\n\n");

        s.push_str("#define INT_FAST64_MIN  INT64_MIN\n");
        s.push_str("#define INT_FAST64_MAX  INT64_MAX\n");
        s.push_str("#define UINT_FAST64_MAX UINT64_MAX\n\n");

        // ── Limits of pointer-sized integers ───────────────────────────
        s.push_str("/* Limits of pointer-sized integer types */\n");
        if self.pointer_width == 64 {
            s.push_str("#define INTPTR_MIN  INT64_MIN\n");
            s.push_str("#define INTPTR_MAX  INT64_MAX\n");
            s.push_str("#define UINTPTR_MAX UINT64_MAX\n\n");
        } else {
            s.push_str("#define INTPTR_MIN  INT32_MIN\n");
            s.push_str("#define INTPTR_MAX  INT32_MAX\n");
            s.push_str("#define UINTPTR_MAX UINT32_MAX\n\n");
        }

        // ── Limits of greatest-width integers ──────────────────────────
        s.push_str("/* Limits of greatest-width integer types */\n");
        s.push_str("#define INTMAX_MIN  INT64_MIN\n");
        s.push_str("#define INTMAX_MAX  INT64_MAX\n");
        s.push_str("#define UINTMAX_MAX UINT64_MAX\n\n");

        // ── Limits of other integer types ──────────────────────────────
        s.push_str("/* Limits of other integer types */\n");

        // PTRDIFF_WIDTH, SIZE_MAX, etc.
        if self.pointer_width == 64 {
            s.push_str("#define PTRDIFF_MIN INT64_MIN\n");
            s.push_str("#define PTRDIFF_MAX INT64_MAX\n\n");
            s.push_str("#define SIZE_MAX UINT64_MAX\n\n");
        } else {
            s.push_str("#define PTRDIFF_MIN INT32_MIN\n");
            s.push_str("#define PTRDIFF_MAX INT32_MAX\n\n");
            s.push_str("#define SIZE_MAX UINT32_MAX\n\n");
        }

        // WCHAR_MIN, WCHAR_MAX
        if self.wchar_width == 16 {
            if self.char_is_signed {
                s.push_str("#define WCHAR_MIN (-32767 - 1)\n");
                s.push_str("#define WCHAR_MAX (32767)\n\n");
            } else {
                s.push_str("#define WCHAR_MIN (0)\n");
                s.push_str("#define WCHAR_MAX (65535)\n\n");
            }
        } else {
            if self.char_is_signed {
                s.push_str("#define WCHAR_MIN (-2147483647 - 1)\n");
                s.push_str("#define WCHAR_MAX (2147483647)\n\n");
            } else {
                s.push_str("#define WCHAR_MIN (0)\n");
                s.push_str("#define WCHAR_MAX (4294967295U)\n\n");
            }
        }

        // WINT_MIN, WINT_MAX
        s.push_str("#define WINT_MIN INT32_MIN\n");
        s.push_str("#define WINT_MAX INT32_MAX\n\n");

        // SIG_ATOMIC_MIN/MAX
        s.push_str("#define SIG_ATOMIC_MIN INT32_MIN\n");
        s.push_str("#define SIG_ATOMIC_MAX INT32_MAX\n\n");

        // ── Macros for integer constant expressions ────────────────────
        s.push_str("/* Macros for integer constant expressions */\n");
        s.push_str("#define INT8_C(c)  c\n");
        s.push_str("#define INT16_C(c) c\n");
        s.push_str("#define INT32_C(c) c\n");
        if self.long_width >= 64 {
            s.push_str("#define INT64_C(c) c ## L\n");
        } else {
            s.push_str("#define INT64_C(c) c ## LL\n");
        }
        s.push_str("#define INTMAX_C(c) c ## LL\n\n");

        s.push_str("#define UINT8_C(c)  c\n");
        s.push_str("#define UINT16_C(c) c\n");
        s.push_str("#define UINT32_C(c) c ## U\n");
        if self.long_width >= 64 {
            s.push_str("#define UINT64_C(c) c ## UL\n");
        } else {
            s.push_str("#define UINT64_C(c) c ## ULL\n");
        }
        s.push_str("#define UINTMAX_C(c) c ## ULL\n\n");

        s.push_str("#endif /* __STDINT_H */\n");
        s
    }

    // ── <stdbool.h> ──────────────────────────────────────────────────────

    fn generate_stdbool(&self) -> String {
        let mut s = String::new();

        s.push_str("#ifndef __STDBOOL_H\n");
        s.push_str("#define __STDBOOL_H\n\n");

        s.push_str("#ifndef __cplusplus\n\n");

        s.push_str("#define bool  _Bool\n");
        s.push_str("#define true  1\n");
        s.push_str("#define false 0\n\n");

        s.push_str("#else /* __cplusplus */\n\n");

        s.push_str("/* In C++, bool/true/false are keywords */\n");
        s.push_str("#define __bool_true_false_are_defined 1\n\n");

        s.push_str("#endif /* __cplusplus */\n\n");

        s.push_str("#define __bool_true_false_are_defined 1\n\n");

        s.push_str("#endif /* __STDBOOL_H */\n");
        s
    }

    // ── <stdarg.h> ───────────────────────────────────────────────────────

    fn generate_stdarg(&self) -> String {
        let mut s = String::new();

        s.push_str("#ifndef __STDARG_H\n");
        s.push_str("#define __STDARG_H\n\n");

        // va_list is compiler-provided
        s.push_str("/* va_list is provided by the compiler */\n");
        s.push_str("typedef __builtin_va_list va_list;\n\n");

        // va_start
        s.push_str("#define va_start(ap, param) ");
        s.push_str("__builtin_va_start(ap, param)\n\n");

        // va_arg
        s.push_str("#define va_arg(ap, type) ");
        s.push_str("__builtin_va_arg(ap, type)\n\n");

        // va_end
        s.push_str("#define va_end(ap) ");
        s.push_str("__builtin_va_end(ap)\n\n");

        // va_copy
        s.push_str("#define va_copy(dest, src) ");
        s.push_str("__builtin_va_copy(dest, src)\n\n");

        // __va_copy (legacy)
        s.push_str("/* Legacy synonym */\n");
        s.push_str("#ifndef __va_copy\n");
        s.push_str("#define __va_copy(dest, src) ");
        s.push_str("__builtin_va_copy(dest, src)\n");
        s.push_str("#endif\n\n");

        s.push_str("#endif /* __STDARG_H */\n");
        s
    }

    // ── <limits.h> ───────────────────────────────────────────────────────

    fn generate_limits(&self) -> String {
        let mut s = String::new();

        s.push_str("#ifndef __LIMITS_H\n");
        s.push_str("#define __LIMITS_H\n\n");

        // ── char widths ────────────────────────────────────────────────
        s.push_str("/* Number of bits in a character */\n");
        s.push_str("#define CHAR_BIT 8\n\n");

        // ── signed char limits ─────────────────────────────────────────
        s.push_str("/* Minimum and maximum values a 'signed char' can hold */\n");
        s.push_str("#define SCHAR_MIN (-128)\n");
        s.push_str("#define SCHAR_MAX 127\n\n");

        // ── unsigned char limits ───────────────────────────────────────
        s.push_str("/* Maximum value an 'unsigned char' can hold */\n");
        s.push_str("#define UCHAR_MAX 255\n\n");

        // ── char limits (depends on signedness) ────────────────────────
        s.push_str("/* Minimum and maximum values a 'char' can hold */\n");
        if self.char_is_signed {
            s.push_str("#define CHAR_MIN  SCHAR_MIN\n");
            s.push_str("#define CHAR_MAX  SCHAR_MAX\n\n");
        } else {
            s.push_str("#define CHAR_MIN  0\n");
            s.push_str("#define CHAR_MAX  UCHAR_MAX\n\n");
        }

        // ── short limits ───────────────────────────────────────────────
        s.push_str("/* Minimum and maximum values a 'short int' can hold */\n");
        if self.short_width == 16 {
            s.push_str("#define SHRT_MIN  (-32768)\n");
            s.push_str("#define SHRT_MAX  32767\n\n");
        } else {
            s.push_str("#define SHRT_MIN  (-32767 - 1)\n");
            s.push_str("#define SHRT_MAX  32767\n\n");
        }

        // ── unsigned short limits ──────────────────────────────────────
        s.push_str("/* Maximum value an 'unsigned short int' can hold */\n");
        if self.short_width == 16 {
            s.push_str("#define USHRT_MAX 65535\n\n");
        } else {
            s.push_str("#define USHRT_MAX 4294967295\n\n");
        }

        // ── int limits ─────────────────────────────────────────────────
        s.push_str("/* Minimum and maximum values an 'int' can hold */\n");
        if self.int_width == 32 {
            s.push_str("#define INT_MIN   (-2147483647 - 1)\n");
            s.push_str("#define INT_MAX   2147483647\n\n");
        } else if self.int_width == 16 {
            s.push_str("#define INT_MIN   (-32768)\n");
            s.push_str("#define INT_MAX   32767\n\n");
        } else {
            s.push_str("#define INT_MIN   (-32767 - 1)\n");
            s.push_str("#define INT_MAX   32767\n\n");
        }

        // ── unsigned int limits ────────────────────────────────────────
        s.push_str("/* Maximum value an 'unsigned int' can hold */\n");
        if self.int_width == 32 {
            s.push_str("#define UINT_MAX  4294967295U\n\n");
        } else {
            s.push_str("#define UINT_MAX  65535U\n\n");
        }

        // ── long limits ────────────────────────────────────────────────
        s.push_str("/* Minimum and maximum values a 'long int' can hold */\n");
        if self.long_width == 64 {
            s.push_str("#define LONG_MIN  (-9223372036854775807L - 1L)\n");
            s.push_str("#define LONG_MAX  9223372036854775807L\n\n");
        } else {
            s.push_str("#define LONG_MIN  (-2147483647L - 1L)\n");
            s.push_str("#define LONG_MAX  2147483647L\n\n");
        }

        // ── unsigned long limits ───────────────────────────────────────
        s.push_str("/* Maximum value an 'unsigned long int' can hold */\n");
        if self.long_width == 64 {
            s.push_str("#define ULONG_MAX 18446744073709551615UL\n\n");
        } else {
            s.push_str("#define ULONG_MAX 4294967295UL\n\n");
        }

        // ── long long limits ───────────────────────────────────────────
        s.push_str("/* Minimum and maximum values a 'long long int' can hold */\n");
        s.push_str("#define LLONG_MIN (-9223372036854775807LL - 1LL)\n");
        s.push_str("#define LLONG_MAX 9223372036854775807LL\n\n");

        // ── unsigned long long limits ──────────────────────────────────
        s.push_str("/* Maximum value an 'unsigned long long int' can hold */\n");
        s.push_str("#define ULLONG_MAX 18446744073709551615ULL\n\n");

        // ── Multibyte character limits ─────────────────────────────────
        s.push_str("#ifndef MB_LEN_MAX\n");
        s.push_str("#define MB_LEN_MAX 16\n");
        s.push_str("#endif\n\n");

        // ── POSIX extensions ───────────────────────────────────────────
        s.push_str("/* POSIX extensions */\n");
        if self.pointer_width == 64 {
            s.push_str("#define SSIZE_MAX LONG_MAX\n\n");
        } else {
            s.push_str("#define SSIZE_MAX INT_MAX\n\n");
        }

        s.push_str("#endif /* __LIMITS_H */\n");
        s
    }

    // ── <float.h> ────────────────────────────────────────────────────────

    fn generate_float(&self) -> String {
        let mut s = String::new();

        s.push_str("#ifndef __FLOAT_H\n");
        s.push_str("#define __FLOAT_H\n\n");

        // ── Characteristics of floating types ──────────────────────────
        s.push_str("/* Characteristics of floating-point types */\n\n");

        // float
        s.push_str("/* float */\n");
        s.push_str("#define FLT_RADIX 2\n");
        s.push_str("#define FLT_MANT_DIG 24\n");
        s.push_str("#define FLT_DIG 6\n");
        s.push_str("#define FLT_MIN_EXP (-125)\n");
        s.push_str("#define FLT_MIN_10_EXP (-37)\n");
        s.push_str("#define FLT_MAX_EXP 128\n");
        s.push_str("#define FLT_MAX_10_EXP 38\n");
        s.push_str("#define FLT_MIN 1.17549435082228750796873653722224568e-38F\n");
        s.push_str("#define FLT_MAX 3.40282346638528859811704183484516925e+38F\n");
        s.push_str("#define FLT_EPSILON 1.1920928955078125e-07F\n");
        s.push_str("#define FLT_TRUE_MIN 1.40129846432481707092372958328991613e-45F\n");
        s.push_str("#define FLT_HAS_SUBNORM 1\n");
        s.push_str("#define FLT_EVAL_METHOD 0\n");
        s.push_str("#define FLT_DECIMAL_DIG 9\n\n");

        // double
        s.push_str("/* double */\n");
        s.push_str("#define DBL_MANT_DIG 53\n");
        s.push_str("#define DBL_DIG 15\n");
        s.push_str("#define DBL_MIN_EXP (-1021)\n");
        s.push_str("#define DBL_MIN_10_EXP (-307)\n");
        s.push_str("#define DBL_MAX_EXP 1024\n");
        s.push_str("#define DBL_MAX_10_EXP 308\n");
        s.push_str("#define DBL_MIN 2.22507385850720138309023271733240406e-308\n");
        s.push_str("#define DBL_MAX 1.79769313486231570814527423731704357e+308\n");
        s.push_str("#define DBL_EPSILON 2.22044604925031308084726333618164062e-16\n");
        s.push_str("#define DBL_TRUE_MIN 4.94065645841246544176568792868221372e-324\n");
        s.push_str("#define DBL_HAS_SUBNORM 1\n");
        s.push_str("#define DBL_DECIMAL_DIG 17\n\n");

        // long double (80-bit x87 for x86; 128-bit for others)
        s.push_str("/* long double */\n");
        if self.pointer_width == 64 && self.little_endian {
            // x86-64 with 80-bit long double
            s.push_str("#define LDBL_MANT_DIG 64\n");
            s.push_str("#define LDBL_DIG 18\n");
            s.push_str("#define LDBL_MIN_EXP (-16381)\n");
            s.push_str("#define LDBL_MIN_10_EXP (-4931)\n");
            s.push_str("#define LDBL_MAX_EXP 16384\n");
            s.push_str("#define LDBL_MAX_10_EXP 4932\n");
            s.push_str("#define LDBL_MIN 3.36210314311209350626267781732175260e-4932L\n");
            s.push_str("#define LDBL_MAX 1.18973149535723176502126385303097021e+4932L\n");
            s.push_str("#define LDBL_EPSILON 1.08420217248550443400745280086994171e-19L\n");
            s.push_str("#define LDBL_TRUE_MIN 3.64519953188247460252840593361941982e-4951L\n");
            s.push_str("#define LDBL_HAS_SUBNORM 1\n");
            s.push_str("#define LDBL_DECIMAL_DIG 21\n\n");
        } else {
            // IEEE 128-bit or double-double
            s.push_str("#define LDBL_MANT_DIG 113\n");
            s.push_str("#define LDBL_DIG 33\n");
            s.push_str("#define LDBL_MIN_EXP (-16381)\n");
            s.push_str("#define LDBL_MIN_10_EXP (-4931)\n");
            s.push_str("#define LDBL_MAX_EXP 16384\n");
            s.push_str("#define LDBL_MAX_10_EXP 4932\n");
            s.push_str("#define LDBL_MIN 3.36210314311209350626267781732175260e-4932L\n");
            s.push_str("#define LDBL_MAX 1.18973149535723176502126385303097021e+4932L\n");
            s.push_str("#define LDBL_EPSILON 1.92592994438723585305597794258492732e-34L\n");
            s.push_str("#define LDBL_TRUE_MIN 6.47517511943802511092443895822764655e-4966L\n");
            s.push_str("#define LDBL_HAS_SUBNORM 1\n");
            s.push_str("#define LDBL_DECIMAL_DIG 36\n\n");
        }

        s.push_str("#endif /* __FLOAT_H */\n");
        s
    }

    // ── <iso646.h> ───────────────────────────────────────────────────────

    fn generate_iso646(&self) -> String {
        let mut s = String::new();

        s.push_str("#ifndef __ISO646_H\n");
        s.push_str("#define __ISO646_H\n\n");

        s.push_str("#ifndef __cplusplus\n\n");

        s.push_str("/* Alternative spellings for operators (ISO 646) */\n");
        s.push_str("#define and    &&\n");
        s.push_str("#define and_eq &=\n");
        s.push_str("#define bitand &\n");
        s.push_str("#define bitor  |\n");
        s.push_str("#define compl  ~\n");
        s.push_str("#define not    !\n");
        s.push_str("#define not_eq !=\n");
        s.push_str("#define or     ||\n");
        s.push_str("#define or_eq  |=\n");
        s.push_str("#define xor    ^\n");
        s.push_str("#define xor_eq ^=\n\n");

        s.push_str("#endif /* __cplusplus */\n\n");

        s.push_str("#endif /* __ISO646_H */\n");
        s
    }

    // ── <stdatomic.h> ────────────────────────────────────────────────────

    fn generate_stdatomic(&self) -> String {
        let mut s = String::new();

        s.push_str("#ifndef __STDATOMIC_H\n");
        s.push_str("#define __STDATOMIC_H\n\n");

        s.push_str("/* Atomic types and operations are compiler builtins */\n\n");

        s.push_str("typedef enum {\n");
        s.push_str("  memory_order_relaxed = __ATOMIC_RELAXED,\n");
        s.push_str("  memory_order_consume = __ATOMIC_CONSUME,\n");
        s.push_str("  memory_order_acquire = __ATOMIC_ACQUIRE,\n");
        s.push_str("  memory_order_release = __ATOMIC_RELEASE,\n");
        s.push_str("  memory_order_acq_rel = __ATOMIC_ACQ_REL,\n");
        s.push_str("  memory_order_seq_cst = __ATOMIC_SEQ_CST\n");
        s.push_str("} memory_order;\n\n");

        s.push_str("#define ATOMIC_BOOL_LOCK_FREE   2\n");
        s.push_str("#define ATOMIC_CHAR_LOCK_FREE   2\n");
        s.push_str("#define ATOMIC_CHAR16_T_LOCK_FREE 2\n");
        s.push_str("#define ATOMIC_CHAR32_T_LOCK_FREE 2\n");
        s.push_str("#define ATOMIC_WCHAR_T_LOCK_FREE 2\n");
        s.push_str("#define ATOMIC_SHORT_LOCK_FREE  2\n");
        s.push_str("#define ATOMIC_INT_LOCK_FREE    2\n");
        s.push_str("#define ATOMIC_LONG_LOCK_FREE   2\n");
        s.push_str("#define ATOMIC_LLONG_LOCK_FREE  2\n");
        s.push_str("#define ATOMIC_POINTER_LOCK_FREE 2\n\n");

        s.push_str("#define atomic_init(obj, value) __c11_atomic_init(obj, value)\n");
        s.push_str("#define atomic_load(obj) __c11_atomic_load(obj, memory_order_seq_cst)\n");
        s.push_str(
            "#define atomic_store(obj, val) __c11_atomic_store(obj, val, memory_order_seq_cst)\n",
        );
        s.push_str("#define atomic_exchange(obj, val) __c11_atomic_exchange(obj, val, memory_order_seq_cst)\n");
        s.push_str("#define atomic_compare_exchange_strong(obj, exp, val) __c11_atomic_compare_exchange_strong(obj, exp, val, memory_order_seq_cst, memory_order_seq_cst)\n");
        s.push_str("#define atomic_compare_exchange_weak(obj, exp, val) __c11_atomic_compare_exchange_weak(obj, exp, val, memory_order_seq_cst, memory_order_seq_cst)\n");
        s.push_str("#define atomic_fetch_add(obj, val) __c11_atomic_fetch_add(obj, val, memory_order_seq_cst)\n");
        s.push_str("#define atomic_fetch_sub(obj, val) __c11_atomic_fetch_sub(obj, val, memory_order_seq_cst)\n");
        s.push_str("#define atomic_fetch_and(obj, val) __c11_atomic_fetch_and(obj, val, memory_order_seq_cst)\n");
        s.push_str("#define atomic_fetch_or(obj, val)  __c11_atomic_fetch_or(obj, val, memory_order_seq_cst)\n");
        s.push_str("#define atomic_fetch_xor(obj, val) __c11_atomic_fetch_xor(obj, val, memory_order_seq_cst)\n");
        s.push_str("#define atomic_thread_fence(order) __c11_atomic_thread_fence(order)\n");
        s.push_str("#define atomic_signal_fence(order) __c11_atomic_signal_fence(order)\n\n");

        s.push_str("#endif /* __STDATOMIC_H */\n");
        s
    }

    // ── <stdalign.h> ─────────────────────────────────────────────────────

    fn generate_stdalign(&self) -> String {
        let mut s = String::new();

        s.push_str("#ifndef __STDALIGN_H\n");
        s.push_str("#define __STDALIGN_H\n\n");

        s.push_str("#ifndef __cplusplus\n\n");

        s.push_str("/* alignas and alignof for C */\n");
        s.push_str("#define alignas _Alignas\n");
        s.push_str("#define alignof _Alignof\n\n");

        s.push_str("#define __alignas_is_defined 1\n");
        s.push_str("#define __alignof_is_defined 1\n\n");

        s.push_str("#endif /* __cplusplus */\n\n");

        s.push_str("#endif /* __STDALIGN_H */\n");
        s
    }

    // ── <stdnoreturn.h> ──────────────────────────────────────────────────

    fn generate_stdnoreturn(&self) -> String {
        let mut s = String::new();

        s.push_str("#ifndef __STDNORETURN_H\n");
        s.push_str("#define __STDNORETURN_H\n\n");

        s.push_str("#ifndef __cplusplus\n\n");

        s.push_str("/* noreturn for C */\n");
        s.push_str("#define noreturn _Noreturn\n\n");

        s.push_str("#endif /* __cplusplus */\n\n");

        s.push_str("#endif /* __STDNORETURN_H */\n");
        s
    }

    // ── <tgmath.h> ───────────────────────────────────────────────────────

    fn generate_tgmath(&self) -> String {
        let mut s = String::new();

        s.push_str("#ifndef __TGMATH_H\n");
        s.push_str("#define __TGMATH_H\n\n");

        s.push_str("/* Type-generic math is handled by compiler builtins */\n");
        s.push_str("#if __has_builtin(__builtin_tgmath)\n\n");

        // sin
        s.push_str("#define sin(x)   __builtin_tgmath(sinf, sin, sinl, x)\n");
        s.push_str("#define cos(x)   __builtin_tgmath(cosf, cos, cosl, x)\n");
        s.push_str("#define tan(x)   __builtin_tgmath(tanf, tan, tanl, x)\n");
        s.push_str("#define asin(x)  __builtin_tgmath(asinf, asin, asinl, x)\n");
        s.push_str("#define acos(x)  __builtin_tgmath(acosf, acos, acosl, x)\n");
        s.push_str("#define atan(x)  __builtin_tgmath(atanf, atan, atanl, x)\n");
        s.push_str("#define atan2(y,x) __builtin_tgmath(atan2f, atan2, atan2l, y, x)\n");
        s.push_str("#define sinh(x)  __builtin_tgmath(sinhf, sinh, sinhl, x)\n");
        s.push_str("#define cosh(x)  __builtin_tgmath(coshf, cosh, coshl, x)\n");
        s.push_str("#define tanh(x)  __builtin_tgmath(tanhf, tanh, tanhl, x)\n");
        s.push_str("#define exp(x)   __builtin_tgmath(expf, exp, expl, x)\n");
        s.push_str("#define log(x)   __builtin_tgmath(logf, log, logl, x)\n");
        s.push_str("#define log10(x) __builtin_tgmath(log10f, log10, log10l, x)\n");
        s.push_str("#define sqrt(x)  __builtin_tgmath(sqrtf, sqrt, sqrtl, x)\n");
        s.push_str("#define fabs(x)  __builtin_tgmath(fabsf, fabs, fabsl, x)\n");
        s.push_str("#define pow(x,y) __builtin_tgmath(powf, pow, powl, x, y)\n");
        s.push_str("#define ceil(x)  __builtin_tgmath(ceilf, ceil, ceill, x)\n");
        s.push_str("#define floor(x) __builtin_tgmath(floorf, floor, floorl, x)\n");
        s.push_str("#define fmod(x,y) __builtin_tgmath(fmodf, fmod, fmodl, x, y)\n\n");

        s.push_str("#endif /* __has_builtin(__builtin_tgmath) */\n\n");

        s.push_str("#endif /* __TGMATH_H */\n");
        s
    }

    // ── <unwind.h> ───────────────────────────────────────────────────────

    fn generate_unwind(&self) -> String {
        let mut s = String::new();

        s.push_str("#ifndef __UNWIND_H\n");
        s.push_str("#define __UNWIND_H\n\n");

        s.push_str("#ifdef __clang__\n\n");
        s.push_str("/* Unwinding types and functions */\n");
        s.push_str("typedef unsigned _Unwind_Word __attribute__((__mode__(__word__)));\n");
        if self.pointer_width == 64 {
            s.push_str("typedef unsigned _Unwind_Ptr __attribute__((__mode__(__DI__)));\n");
        } else {
            s.push_str("typedef unsigned _Unwind_Ptr __attribute__((__mode__(__SI__)));\n");
        }
        s.push_str(
            "typedef unsigned _Unwind_Exception_Class __attribute__((__mode__(__DI__)));\n\n",
        );

        s.push_str("struct _Unwind_Exception;\n");
        s.push_str("struct _Unwind_Context;\n\n");

        s.push_str("typedef void (*_Unwind_Exception_Cleanup_Fn)");
        s.push_str("(_Unwind_Reason_Code reason, struct _Unwind_Exception *exc);\n\n");

        s.push_str("struct _Unwind_Exception {\n");
        s.push_str("  _Unwind_Exception_Class exception_class;\n");
        s.push_str("  _Unwind_Exception_Cleanup_Fn exception_cleanup;\n");
        if self.pointer_width == 64 {
            s.push_str("  _Unwind_Word private_1;\n");
            s.push_str("  _Unwind_Word private_2;\n");
        } else {
            s.push_str("  _Unwind_Word private_1;\n");
        }
        s.push_str("} __attribute__((__aligned__));\n\n");

        s.push_str("typedef enum {\n");
        s.push_str("  _URC_NO_REASON = 0,\n");
        s.push_str("  _URC_FOREIGN_EXCEPTION_CAUGHT = 1,\n");
        s.push_str("  _URC_FATAL_PHASE2_ERROR = 2,\n");
        s.push_str("  _URC_FATAL_PHASE1_ERROR = 3,\n");
        s.push_str("  _URC_NORMAL_STOP = 4,\n");
        s.push_str("  _URC_END_OF_STACK = 5,\n");
        s.push_str("  _URC_HANDLER_FOUND = 6,\n");
        s.push_str("  _URC_INSTALL_CONTEXT = 7,\n");
        s.push_str("  _URC_CONTINUE_UNWIND = 8\n");
        s.push_str("} _Unwind_Reason_Code;\n\n");

        s.push_str("typedef enum {\n");
        s.push_str("  _UA_SEARCH_PHASE = 1,\n");
        s.push_str("  _UA_CLEANUP_PHASE = 2,\n");
        s.push_str("  _UA_HANDLER_FRAME = 4,\n");
        s.push_str("  _UA_FORCE_UNWIND = 8,\n");
        s.push_str("  _UA_END_OF_STACK = 16\n");
        s.push_str("} _Unwind_Action;\n\n");

        s.push_str("#endif /* __clang__ */\n\n");

        s.push_str("#endif /* __UNWIND_H */\n");
        s
    }
}

impl Default for BuiltinHeaderGenerator {
    fn default() -> Self {
        Self::new_x86_64_linux()
    }
}

// ═══════════════════════════════════════════════════════════════════════════
// Compiler Builtin Declarations  (not header text, but semantic definitions)
// ═══════════════════════════════════════════════════════════════════════════

/// Semantic information for a compiler builtin function.
#[derive(Debug, Clone)]
pub struct BuiltinFunction {
    /// The builtin name (e.g. `"__builtin_alloca"`).
    pub name: String,
    /// How many operands the builtin takes.
    pub num_operands: usize,
    /// Whether the builtin returns a value.
    pub has_return: bool,
    /// Whether the builtin is pure (no side effects aside from its
    /// operands).
    pub is_pure: bool,
    /// Whether the builtin never returns (like `__builtin_unreachable`).
    pub is_noreturn: bool,
    /// Whether the builtin is const (no side effects, deterministic).
    pub is_const: bool,
    /// Whether the builtin is a "returns twice" function (e.g. `fork`,
    /// `setjmp`).
    pub returns_twice: bool,
    /// Category tag for grouping related builtins.
    pub category: BuiltinCategory,
}

/// Category of compiler builtin.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum BuiltinCategory {
    Memory,
    Math,
    String,
    Io,
    Atomic,
    Vector,
    TypeTrait,
    Overflow,
    Expect,
    ObjectSize,
    Prefetch,
    Trap,
    Other,
}

/// Registry of known compiler builtins with their semantics.
#[derive(Debug, Clone)]
pub struct BuiltinRegistry {
    builtins: HashMap<String, BuiltinFunction>,
}

impl BuiltinRegistry {
    pub fn new() -> Self {
        let mut reg = Self {
            builtins: HashMap::new(),
        };
        reg.register_defaults();
        reg
    }

    fn register(&mut self, name: &str, func: BuiltinFunction) {
        self.builtins.insert(name.to_string(), func);
    }

    fn register_defaults(&mut self) {
        // ── Memory builtins ─────────────────────────────────────────
        self.register(
            "__builtin_alloca",
            BuiltinFunction {
                name: "__builtin_alloca".into(),
                num_operands: 1,
                has_return: true,
                is_pure: false,
                is_noreturn: false,
                is_const: false,
                returns_twice: false,
                category: BuiltinCategory::Memory,
            },
        );
        self.register(
            "__builtin_alloca_with_align",
            BuiltinFunction {
                name: "__builtin_alloca_with_align".into(),
                num_operands: 2,
                has_return: true,
                is_pure: false,
                is_noreturn: false,
                is_const: false,
                returns_twice: false,
                category: BuiltinCategory::Memory,
            },
        );
        self.register(
            "__builtin_assume_aligned",
            BuiltinFunction {
                name: "__builtin_assume_aligned".into(),
                num_operands: 2,
                has_return: true,
                is_pure: true,
                is_noreturn: false,
                is_const: false,
                returns_twice: false,
                category: BuiltinCategory::Memory,
            },
        );
        self.register(
            "__builtin_memcpy",
            BuiltinFunction {
                name: "__builtin_memcpy".into(),
                num_operands: 3,
                has_return: true,
                is_pure: false,
                is_noreturn: false,
                is_const: false,
                returns_twice: false,
                category: BuiltinCategory::Memory,
            },
        );
        self.register(
            "__builtin_memmove",
            BuiltinFunction {
                name: "__builtin_memmove".into(),
                num_operands: 3,
                has_return: true,
                is_pure: false,
                is_noreturn: false,
                is_const: false,
                returns_twice: false,
                category: BuiltinCategory::Memory,
            },
        );
        self.register(
            "__builtin_memset",
            BuiltinFunction {
                name: "__builtin_memset".into(),
                num_operands: 3,
                has_return: true,
                is_pure: false,
                is_noreturn: false,
                is_const: false,
                returns_twice: false,
                category: BuiltinCategory::Memory,
            },
        );

        // ── Type trait builtins ─────────────────────────────────────
        self.register(
            "__builtin_types_compatible_p",
            BuiltinFunction {
                name: "__builtin_types_compatible_p".into(),
                num_operands: 2,
                has_return: true,
                is_pure: true,
                is_noreturn: false,
                is_const: true,
                returns_twice: false,
                category: BuiltinCategory::TypeTrait,
            },
        );
        self.register(
            "__builtin_choose_expr",
            BuiltinFunction {
                name: "__builtin_choose_expr".into(),
                num_operands: 3,
                has_return: true,
                is_pure: true,
                is_noreturn: false,
                is_const: true,
                returns_twice: false,
                category: BuiltinCategory::TypeTrait,
            },
        );
        self.register(
            "__builtin_is_constant_evaluated",
            BuiltinFunction {
                name: "__builtin_is_constant_evaluated".into(),
                num_operands: 0,
                has_return: true,
                is_pure: true,
                is_noreturn: false,
                is_const: true,
                returns_twice: false,
                category: BuiltinCategory::TypeTrait,
            },
        );

        // ── Overflow builtins ───────────────────────────────────────
        self.register(
            "__builtin_add_overflow",
            BuiltinFunction {
                name: "__builtin_add_overflow".into(),
                num_operands: 3,
                has_return: true,
                is_pure: false,
                is_noreturn: false,
                is_const: false,
                returns_twice: false,
                category: BuiltinCategory::Overflow,
            },
        );
        self.register(
            "__builtin_sub_overflow",
            BuiltinFunction {
                name: "__builtin_sub_overflow".into(),
                num_operands: 3,
                has_return: true,
                is_pure: false,
                is_noreturn: false,
                is_const: false,
                returns_twice: false,
                category: BuiltinCategory::Overflow,
            },
        );
        self.register(
            "__builtin_mul_overflow",
            BuiltinFunction {
                name: "__builtin_mul_overflow".into(),
                num_operands: 3,
                has_return: true,
                is_pure: false,
                is_noreturn: false,
                is_const: false,
                returns_twice: false,
                category: BuiltinCategory::Overflow,
            },
        );
        self.register(
            "__builtin_add_overflow_p",
            BuiltinFunction {
                name: "__builtin_add_overflow_p".into(),
                num_operands: 3,
                has_return: true,
                is_pure: true,
                is_noreturn: false,
                is_const: true,
                returns_twice: false,
                category: BuiltinCategory::Overflow,
            },
        );
        self.register(
            "__builtin_sub_overflow_p",
            BuiltinFunction {
                name: "__builtin_sub_overflow_p".into(),
                num_operands: 3,
                has_return: true,
                is_pure: true,
                is_noreturn: false,
                is_const: true,
                returns_twice: false,
                category: BuiltinCategory::Overflow,
            },
        );
        self.register(
            "__builtin_mul_overflow_p",
            BuiltinFunction {
                name: "__builtin_mul_overflow_p".into(),
                num_operands: 3,
                has_return: true,
                is_pure: true,
                is_noreturn: false,
                is_const: true,
                returns_twice: false,
                category: BuiltinCategory::Overflow,
            },
        );

        // ── Expect / likelihood builtins ────────────────────────────
        self.register(
            "__builtin_expect",
            BuiltinFunction {
                name: "__builtin_expect".into(),
                num_operands: 2,
                has_return: true,
                is_pure: true,
                is_noreturn: false,
                is_const: false,
                returns_twice: false,
                category: BuiltinCategory::Expect,
            },
        );
        self.register(
            "__builtin_expect_with_probability",
            BuiltinFunction {
                name: "__builtin_expect_with_probability".into(),
                num_operands: 3,
                has_return: true,
                is_pure: true,
                is_noreturn: false,
                is_const: false,
                returns_twice: false,
                category: BuiltinCategory::Expect,
            },
        );
        self.register(
            "__builtin_unpredictable",
            BuiltinFunction {
                name: "__builtin_unpredictable".into(),
                num_operands: 1,
                has_return: true,
                is_pure: true,
                is_noreturn: false,
                is_const: false,
                returns_twice: false,
                category: BuiltinCategory::Expect,
            },
        );

        // ── Object size / bounds checking ───────────────────────────
        self.register(
            "__builtin_object_size",
            BuiltinFunction {
                name: "__builtin_object_size".into(),
                num_operands: 2,
                has_return: true,
                is_pure: true,
                is_noreturn: false,
                is_const: true,
                returns_twice: false,
                category: BuiltinCategory::ObjectSize,
            },
        );
        self.register(
            "__builtin_dynamic_object_size",
            BuiltinFunction {
                name: "__builtin_dynamic_object_size".into(),
                num_operands: 2,
                has_return: true,
                is_pure: true,
                is_noreturn: false,
                is_const: false,
                returns_twice: false,
                category: BuiltinCategory::ObjectSize,
            },
        );

        // ── Prefetch ────────────────────────────────────────────────
        self.register(
            "__builtin_prefetch",
            BuiltinFunction {
                name: "__builtin_prefetch".into(),
                num_operands: 3,
                has_return: false,
                is_pure: false,
                is_noreturn: false,
                is_const: false,
                returns_twice: false,
                category: BuiltinCategory::Prefetch,
            },
        );

        // ── Trap / unreachable ──────────────────────────────────────
        self.register(
            "__builtin_trap",
            BuiltinFunction {
                name: "__builtin_trap".into(),
                num_operands: 0,
                has_return: false,
                is_pure: false,
                is_noreturn: true,
                is_const: false,
                returns_twice: false,
                category: BuiltinCategory::Trap,
            },
        );
        self.register(
            "__builtin_unreachable",
            BuiltinFunction {
                name: "__builtin_unreachable".into(),
                num_operands: 0,
                has_return: false,
                is_pure: false,
                is_noreturn: true,
                is_const: false,
                returns_twice: false,
                category: BuiltinCategory::Trap,
            },
        );
        self.register(
            "__builtin_debugtrap",
            BuiltinFunction {
                name: "__builtin_debugtrap".into(),
                num_operands: 0,
                has_return: false,
                is_pure: false,
                is_noreturn: false,
                is_const: false,
                returns_twice: false,
                category: BuiltinCategory::Trap,
            },
        );

        // ── Miscellaneous ───────────────────────────────────────────
        self.register(
            "__builtin_return_address",
            BuiltinFunction {
                name: "__builtin_return_address".into(),
                num_operands: 1,
                has_return: true,
                is_pure: true,
                is_noreturn: false,
                is_const: false,
                returns_twice: false,
                category: BuiltinCategory::Other,
            },
        );
        self.register(
            "__builtin_frame_address",
            BuiltinFunction {
                name: "__builtin_frame_address".into(),
                num_operands: 1,
                has_return: true,
                is_pure: true,
                is_noreturn: false,
                is_const: false,
                returns_twice: false,
                category: BuiltinCategory::Other,
            },
        );
        self.register(
            "__builtin___clear_cache",
            BuiltinFunction {
                name: "__builtin___clear_cache".into(),
                num_operands: 2,
                has_return: false,
                is_pure: false,
                is_noreturn: false,
                is_const: false,
                returns_twice: false,
                category: BuiltinCategory::Memory,
            },
        );
    }

    /// Look up a builtin by name.
    pub fn lookup(&self, name: &str) -> Option<&BuiltinFunction> {
        self.builtins.get(name)
    }

    /// Check whether a given function name is a known compiler builtin.
    pub fn is_builtin(&self, name: &str) -> bool {
        self.builtins.contains_key(name)
    }

    /// List all registered builtin names.
    pub fn builtin_names(&self) -> Vec<&String> {
        self.builtins.keys().collect()
    }

    /// Get the count of registered builtins.
    pub fn builtin_count(&self) -> usize {
        self.builtins.len()
    }
}

impl Default for BuiltinRegistry {
    fn default() -> Self {
        Self::new()
    }
}

// ═══════════════════════════════════════════════════════════════════════════
// Builtin Header Include Resolver
// ═══════════════════════════════════════════════════════════════════════════

/// Resolves `#include` requests for compiler-provided builtin headers.
///
/// When the preprocessor encounters `#include <stddef.h>` and the
/// platform does not have a system header, the resolver provides the
/// compiler-generated content.
#[derive(Debug, Clone)]
pub struct BuiltinIncludeResolver {
    generator: BuiltinHeaderGenerator,
    cache: HashMap<String, String>,
}

impl BuiltinIncludeResolver {
    pub fn new(generator: BuiltinHeaderGenerator) -> Self {
        Self {
            generator,
            cache: HashMap::new(),
        }
    }

    /// Look up the content of a builtin header by its include name.
    pub fn resolve(&mut self, header_name: &str) -> Option<&str> {
        // Normalise the header name
        let normalized = header_name
            .trim_matches('"')
            .trim_matches('<')
            .trim_matches('>');

        // Try all known builtin headers
        let all = [
            BuiltinHeader::Stddef,
            BuiltinHeader::Stdint,
            BuiltinHeader::Stdbool,
            BuiltinHeader::Stdarg,
            BuiltinHeader::Limits,
            BuiltinHeader::Float,
            BuiltinHeader::Iso646,
            BuiltinHeader::Stdatomic,
            BuiltinHeader::Stdalign,
            BuiltinHeader::Stdnoreturn,
            BuiltinHeader::Tgmath,
            BuiltinHeader::Unwind,
            BuiltinHeader::Cfloat,
        ];

        for h in &all {
            if h.filename() == normalized {
                let entry = self.cache.entry(h.filename().to_string());
                let content = entry.or_insert_with(|| self.generator.generate(*h));
                return Some(content.as_str());
            }
        }

        None
    }

    /// Check whether a given include name is a known builtin header.
    pub fn is_builtin_header(&self, header_name: &str) -> bool {
        let normalized = header_name
            .trim_matches('"')
            .trim_matches('<')
            .trim_matches('>');
        let all = [
            BuiltinHeader::Stddef,
            BuiltinHeader::Stdint,
            BuiltinHeader::Stdbool,
            BuiltinHeader::Stdarg,
            BuiltinHeader::Limits,
            BuiltinHeader::Float,
            BuiltinHeader::Iso646,
            BuiltinHeader::Stdatomic,
            BuiltinHeader::Stdalign,
            BuiltinHeader::Stdnoreturn,
            BuiltinHeader::Tgmath,
            BuiltinHeader::Unwind,
        ];
        all.iter().any(|h| h.filename() == normalized)
    }

    /// Pre-warm the cache with all known builtin headers.
    pub fn prewarm_cache(&mut self) {
        self.generator
            .generate_all()
            .into_iter()
            .for_each(|(k, v)| {
                self.cache.insert(k, v);
            });
    }

    /// Clear the cache (to pick up target changes).
    pub fn clear_cache(&mut self) {
        self.cache.clear();
    }
}

impl Default for BuiltinIncludeResolver {
    fn default() -> Self {
        Self::new(BuiltinHeaderGenerator::default())
    }
}

// ═══════════════════════════════════════════════════════════════════════════
// Tests
// ═══════════════════════════════════════════════════════════════════════════

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_builtin_header_filename() {
        assert_eq!(BuiltinHeader::Stddef.filename(), "stddef.h");
        assert_eq!(BuiltinHeader::Stdint.filename(), "stdint.h");
        assert_eq!(BuiltinHeader::Stdbool.filename(), "stdbool.h");
        assert_eq!(BuiltinHeader::Stdarg.filename(), "stdarg.h");
        assert_eq!(BuiltinHeader::Limits.filename(), "limits.h");
        assert_eq!(BuiltinHeader::Float.filename(), "float.h");
        assert_eq!(BuiltinHeader::Iso646.filename(), "iso646.h");
    }

    #[test]
    fn test_builtin_header_categories() {
        assert!(BuiltinHeader::Stddef.is_c89());
        assert!(BuiltinHeader::Limits.is_c89());
        assert!(!BuiltinHeader::Stdbool.is_c89());
        assert!(BuiltinHeader::Stdbool.is_c99());
        assert!(BuiltinHeader::Stdatomic.is_c11());
        assert!(!BuiltinHeader::Stdatomic.is_c89());
    }

    #[test]
    fn test_generate_stddef_x86_64() {
        let gen = BuiltinHeaderGenerator::new_x86_64_linux();
        let content = gen.generate(BuiltinHeader::Stddef);
        assert!(content.contains("typedef unsigned long size_t;"));
        assert!(content.contains("typedef long ptrdiff_t;"));
        assert!(content.contains("__builtin_offsetof"));
        assert!(content.contains("max_align_t"));
        assert!(content.contains("NULL"));
    }

    #[test]
    fn test_generate_stdint_x86_64() {
        let gen = BuiltinHeaderGenerator::new_x86_64_linux();
        let content = gen.generate(BuiltinHeader::Stdint);
        assert!(content.contains("int8_t"));
        assert!(content.contains("uint64_t"));
        assert!(content.contains("INT32_MAX"));
        assert!(content.contains("SIZE_MAX"));
    }

    #[test]
    fn test_generate_stdbool() {
        let gen = BuiltinHeaderGenerator::new_x86_64_linux();
        let content = gen.generate(BuiltinHeader::Stdbool);
        assert!(content.contains("#define bool  _Bool"));
        assert!(content.contains("#define true  1"));
        assert!(content.contains("#define false 0"));
        assert!(content.contains("__bool_true_false_are_defined"));
    }

    #[test]
    fn test_generate_stdarg() {
        let gen = BuiltinHeaderGenerator::new_x86_64_linux();
        let content = gen.generate(BuiltinHeader::Stdarg);
        assert!(content.contains("__builtin_va_list"));
        assert!(content.contains("__builtin_va_start"));
        assert!(content.contains("__builtin_va_arg"));
        assert!(content.contains("__builtin_va_end"));
        assert!(content.contains("__builtin_va_copy"));
    }

    #[test]
    fn test_generate_limits_x86_64() {
        let gen = BuiltinHeaderGenerator::new_x86_64_linux();
        let content = gen.generate(BuiltinHeader::Limits);
        assert!(content.contains("CHAR_BIT"));
        assert!(content.contains("SCHAR_MIN"));
        assert!(content.contains("LONG_MAX"));
        assert!(content.contains("ULLONG_MAX"));
    }

    #[test]
    fn test_generate_limits_arm() {
        let gen = BuiltinHeaderGenerator::new_arm_linux();
        let content = gen.generate(BuiltinHeader::Limits);
        assert!(content.contains("CHAR_MIN  0")); // unsigned char on ARM
        assert!(content.contains("LONG_MAX  2147483647L"));
    }

    #[test]
    fn test_generate_float() {
        let gen = BuiltinHeaderGenerator::new_x86_64_linux();
        let content = gen.generate(BuiltinHeader::Float);
        assert!(content.contains("FLT_RADIX 2"));
        assert!(content.contains("FLT_MANT_DIG"));
        assert!(content.contains("DBL_EPSILON"));
        assert!(content.contains("LDBL_MANT_DIG"));
    }

    #[test]
    fn test_generate_iso646() {
        let gen = BuiltinHeaderGenerator::new_x86_64_linux();
        let content = gen.generate(BuiltinHeader::Iso646);
        assert!(content.contains("#define and    &&"));
        assert!(content.contains("#define or     ||"));
        assert!(content.contains("#define not    !"));
        assert!(content.contains("#define xor    ^"));
    }

    #[test]
    fn test_generate_stdatomic() {
        let gen = BuiltinHeaderGenerator::new_x86_64_linux();
        let content = gen.generate(BuiltinHeader::Stdatomic);
        assert!(content.contains("memory_order_seq_cst"));
        assert!(content.contains("ATOMIC_BOOL_LOCK_FREE"));
        assert!(content.contains("__c11_atomic_init"));
    }

    #[test]
    fn test_generate_stdalign() {
        let gen = BuiltinHeaderGenerator::new_x86_64_linux();
        let content = gen.generate(BuiltinHeader::Stdalign);
        assert!(content.contains("#define alignas _Alignas"));
        assert!(content.contains("#define alignof _Alignof"));
    }

    #[test]
    fn test_generate_stdnoreturn() {
        let gen = BuiltinHeaderGenerator::new_x86_64_linux();
        let content = gen.generate(BuiltinHeader::Stdnoreturn);
        assert!(content.contains("#define noreturn _Noreturn"));
    }

    #[test]
    fn test_generate_tgmath() {
        let gen = BuiltinHeaderGenerator::new_x86_64_linux();
        let content = gen.generate(BuiltinHeader::Tgmath);
        assert!(content.contains("__builtin_tgmath"));
        assert!(content.contains("sin"));
        assert!(content.contains("sqrt"));
    }

    #[test]
    fn test_generate_unwind() {
        let gen = BuiltinHeaderGenerator::new_x86_64_linux();
        let content = gen.generate(BuiltinHeader::Unwind);
        assert!(content.contains("_Unwind_Exception"));
        assert!(content.contains("_Unwind_Reason_Code"));
        assert!(content.contains("_URC_END_OF_STACK"));
    }

    #[test]
    fn test_generate_all() {
        let gen = BuiltinHeaderGenerator::new_x86_64_linux();
        let map = gen.generate_all();
        assert!(map.contains_key("stddef.h"));
        assert!(map.contains_key("stdint.h"));
        assert!(map.contains_key("stdbool.h"));
        assert!(map.contains_key("stdarg.h"));
        assert!(map.contains_key("limits.h"));
        assert!(map.contains_key("float.h"));
    }

    #[test]
    fn test_builtin_registry_memory() {
        let reg = BuiltinRegistry::new();
        let ba = reg.lookup("__builtin_alloca").unwrap();
        assert_eq!(ba.num_operands, 1);
        assert!(ba.has_return);

        let bm = reg.lookup("__builtin_memcpy").unwrap();
        assert_eq!(bm.num_operands, 3);
        assert_eq!(bm.category, BuiltinCategory::Memory);
    }

    #[test]
    fn test_builtin_registry_type_trait() {
        let reg = BuiltinRegistry::new();
        let bt = reg.lookup("__builtin_types_compatible_p").unwrap();
        assert!(bt.is_const);
        assert_eq!(bt.category, BuiltinCategory::TypeTrait);

        let bc = reg.lookup("__builtin_choose_expr").unwrap();
        assert_eq!(bc.num_operands, 3);
    }

    #[test]
    fn test_builtin_registry_overflow() {
        let reg = BuiltinRegistry::new();
        let ba = reg.lookup("__builtin_add_overflow").unwrap();
        assert_eq!(ba.category, BuiltinCategory::Overflow);
        assert_eq!(ba.num_operands, 3);

        let bm = reg.lookup("__builtin_mul_overflow").unwrap();
        assert_eq!(bm.category, BuiltinCategory::Overflow);

        assert!(reg.lookup("__builtin_sub_overflow").is_some());
    }

    #[test]
    fn test_builtin_registry_expect() {
        let reg = BuiltinRegistry::new();
        let be = reg.lookup("__builtin_expect").unwrap();
        assert_eq!(be.category, BuiltinCategory::Expect);
        assert!(be.is_pure);

        let bp = reg.lookup("__builtin_expect_with_probability").unwrap();
        assert_eq!(bp.num_operands, 3);
    }

    #[test]
    fn test_builtin_registry_trap() {
        let reg = BuiltinRegistry::new();
        let bt = reg.lookup("__builtin_trap").unwrap();
        assert!(bt.is_noreturn);

        let bu = reg.lookup("__builtin_unreachable").unwrap();
        assert!(bu.is_noreturn);
    }

    #[test]
    fn test_builtin_registry_count() {
        let reg = BuiltinRegistry::new();
        assert!(reg.builtin_count() >= 20);
    }

    #[test]
    fn test_builtin_registry_is_builtin() {
        let reg = BuiltinRegistry::new();
        assert!(reg.is_builtin("__builtin_memset"));
        assert!(!reg.is_builtin("nonexistent_func"));
    }

    #[test]
    fn test_builtin_include_resolver_resolve() {
        let gen = BuiltinHeaderGenerator::new_x86_64_linux();
        let mut resolver = BuiltinIncludeResolver::new(gen);
        let content = resolver.resolve("stddef.h").unwrap();
        assert!(content.contains("size_t"));
    }

    #[test]
    fn test_builtin_include_resolver_is_builtin_header() {
        let gen = BuiltinHeaderGenerator::new_x86_64_linux();
        let resolver = BuiltinIncludeResolver::new(gen);
        assert!(resolver.is_builtin_header("stddef.h"));
        assert!(resolver.is_builtin_header("stdint.h"));
        assert!(!resolver.is_builtin_header("stdio.h")); // not a builtin
    }

    #[test]
    fn test_builtin_include_resolver_cache() {
        let gen = BuiltinHeaderGenerator::new_x86_64_linux();
        let mut resolver = BuiltinIncludeResolver::new(gen);
        // First call triggers generation
        let _c1 = resolver.resolve("stddef.h").unwrap();
        // Second call should use cache
        let _c2 = resolver.resolve("stddef.h").unwrap();
    }

    #[test]
    fn test_generator_new_aarch64() {
        let gen = BuiltinHeaderGenerator::new_aarch64_linux();
        assert_eq!(gen.pointer_width, 64);
        assert!(!gen.char_is_signed); // ARM variant
    }

    #[test]
    fn test_generator_new_x86() {
        let gen = BuiltinHeaderGenerator::new_x86_linux();
        assert_eq!(gen.pointer_width, 32);
        assert_eq!(gen.long_width, 32);
        let content = gen.generate(BuiltinHeader::Stdint);
        // 32-bit targets use long long for int64
        assert!(content.contains("long long"));
    }

    #[test]
    fn test_builtin_header_attributes() {
        let gen = BuiltinHeaderGenerator::new_x86_64_linux();
        let content = gen.generate(BuiltinHeader::Stddef);
        assert!(content.contains("__attribute__((__aligned__"));
    }

    #[test]
    fn test_generate_float_double_epsilon() {
        let gen = BuiltinHeaderGenerator::new_x86_64_linux();
        let content = gen.generate(BuiltinHeader::Float);
        assert!(content.contains("DBL_EPSILON"));
        assert!(content.contains("FLT_EPSILON"));
    }

    #[test]
    fn test_generate_stdint_constant_macros_x86_64() {
        let gen = BuiltinHeaderGenerator::new_x86_64_linux();
        let content = gen.generate(BuiltinHeader::Stdint);
        // On 64-bit, int64 uses L suffix
        assert!(content.contains("INT64_C(c) c ## L"));
    }

    #[test]
    fn test_generate_stdint_ptr_x86_32() {
        let gen = BuiltinHeaderGenerator::new_x86_linux();
        let content = gen.generate(BuiltinHeader::Stdint);
        assert!(content.contains("typedef int               intptr_t;"));
    }
}