use crate::spec::{LinkArgs, LinkerFlavor, TargetOptions};
use std::default::Default;
pub fn opts() -> TargetOptions {
let mut pre_link_args = LinkArgs::new();
pre_link_args.insert(LinkerFlavor::Gcc, vec![
// And here, we see obscure linker flags #45. On windows, it has been
// found to be necessary to have this flag to compile liblibc.
//
// First a bit of background. On Windows, the file format is not ELF,
// but COFF (at least according to LLVM). COFF doesn't officially allow
// for section names over 8 characters, apparently. Our metadata
// section, ".note.rustc", you'll note is over 8 characters.
//
// On more recent versions of gcc on mingw, apparently the section name
// is *not* truncated, but rather stored elsewhere in a separate lookup
// table. On older versions of gcc, they apparently always truncated th
// section names (at least in some cases). Truncating the section name
// actually creates "invalid" objects [1] [2], but only for some
// introspection tools, not in terms of whether it can be loaded.
//
// Long story short, passing this flag forces the linker to *not*
// truncate section names (so we can find the metadata section after
// it's compiled). The real kicker is that rust compiled just fine on
// windows for quite a long time *without* this flag, so I have no idea
// why it suddenly started failing for liblibc. Regardless, we
// definitely don't want section name truncation, so we're keeping this
// flag for windows.
//
// [1] - https://sourceware.org/bugzilla/show_bug.cgi?id=13130
// [2] - https://code.google.com/p/go/issues/detail?id=2139
"-Wl,--enable-long-section-names".to_string(),
// Tell GCC to avoid linker plugins, because we are not bundling
// them with Windows installer, and Rust does its own LTO anyways.
"-fno-use-linker-plugin".to_string(),
// Always enable DEP (NX bit) when it is available
"-Wl,--nxcompat".to_string(),
// Do not use the standard system startup files or libraries when linking
"-nostdlib".to_string(),
]);
let mut late_link_args = LinkArgs::new();
late_link_args.insert(LinkerFlavor::Gcc, vec![
"-lmingwex".to_string(),
"-lmingw32".to_string(),
"-lgcc".to_string(), // alas, mingw* libraries above depend on libgcc
"-lmsvcrt".to_string(),
// mingw's msvcrt is a weird hybrid import library and static library.
// And it seems that the linker fails to use import symbols from msvcrt
// that are required from functions in msvcrt in certain cases. For example
// `_fmode` that is used by an implementation of `__p__fmode` in x86_64.
// Listing the library twice seems to fix that, and seems to also be done
// by mingw's gcc (Though not sure if it's done on purpose, or by mistake).
//
// See https://github.com/rust-lang/rust/pull/47483
"-lmsvcrt".to_string(),
"-luser32".to_string(),
"-lkernel32".to_string(),
]);
TargetOptions {
// FIXME(#13846) this should be enabled for windows
function_sections: false,
linker: Some("gcc".to_string()),
dynamic_linking: true,
executables: true,
dll_prefix: String::new(),
dll_suffix: ".dll".to_string(),
exe_suffix: ".exe".to_string(),
staticlib_prefix: String::new(),
staticlib_suffix: ".lib".to_string(),
no_default_libraries: true,
target_family: Some("windows".to_string()),
is_like_windows: true,
allows_weak_linkage: false,
pre_link_args,
pre_link_objects_exe: vec![
"crt2.o".to_string(), // mingw C runtime initialization for executables
"rsbegin.o".to_string(), // Rust compiler runtime initialization, see rsbegin.rs
],
pre_link_objects_dll: vec![
"dllcrt2.o".to_string(), // mingw C runtime initialization for dlls
"rsbegin.o".to_string(),
],
late_link_args,
post_link_objects: vec![
"rsend.o".to_string()
],
custom_unwind_resume: true,
abi_return_struct_as_int: true,
emit_debug_gdb_scripts: false,
requires_uwtable: true,
.. Default::default()
}
}