mago-analyzer 1.43.0

A PHP static analyzer that can detect type errors in PHP code, and provide suggestions for fixing them.
Documentation 
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use mago_allocator::Arena;
use std::rc::Rc;

use mago_codex::ttype::TType;
use mago_codex::ttype::get_minus_one_int;
use mago_codex::ttype::get_mixed;
use mago_codex::ttype::get_one_int;
use mago_codex::ttype::get_signum_result;
use mago_codex::ttype::get_zero_int;
use mago_codex::ttype::union::TUnion;
use mago_reporting::Annotation;
use mago_reporting::Issue;
use mago_span::HasSpan;
use mago_syntax::cst::Binary;
use mago_syntax::cst::Expression;

use crate::analyzable::Analyzable;
use crate::artifacts::AnalysisArtifacts;
use crate::artifacts::get_expression_range;
use crate::code::IssueCode;
use crate::context::Context;
use crate::context::block::BlockContext;
use crate::error::AnalysisError;
use crate::expression::binary::utils::is_always_greater_than;
use crate::expression::binary::utils::is_always_identical_to;
use crate::expression::binary::utils::is_always_less_than;

/// Analyzes the spaceship operator (`LHS <=> RHS`).
///
/// The spaceship operator always returns an integer (`-1`, `0`, or `1`).
/// This function analyzes both operands, sets the result type to `int`,
/// reports warnings for potentially problematic comparisons (e.g., array with int),
/// and errors for invalid comparisons (e.g., involving `mixed`).
/// Data flow is established from both operands.
pub fn analyze_spaceship_operation<'ctx, 'arena, A>(
    binary: &Binary<'arena>,
    context: &mut Context<'ctx, 'arena, A>,
    block_context: &mut BlockContext<'ctx>,
    artifacts: &mut AnalysisArtifacts,
) -> Result<(), AnalysisError>
where
    A: Arena,
{
    binary.lhs.analyze(context, block_context, artifacts)?;
    binary.rhs.analyze(context, block_context, artifacts)?;

    let fallback_type = Rc::new(get_mixed());
    let lhs_type = artifacts.get_rc_expression_type(&binary.lhs).unwrap_or(&fallback_type);
    let rhs_type = artifacts.get_rc_expression_type(&binary.rhs).unwrap_or(&fallback_type);

    check_spaceship_operand(context, binary.lhs, lhs_type, "Left");
    check_spaceship_operand(context, binary.rhs, rhs_type, "Right");

    let lhs_has_array = lhs_type.has_array() || lhs_type.has_iterable();
    let rhs_has_array = rhs_type.has_array() || rhs_type.has_iterable();
    let lhs_is_only_array = lhs_type.is_array();
    let rhs_is_only_array = rhs_type.is_array();

    if lhs_is_only_array && !rhs_has_array && !rhs_type.is_null() {
        context.collector.report_with_code(
            IssueCode::InvalidOperand,
            Issue::error(format!(
                "Comparing an `array` with a non-array type `{}` using `<=>`.",
                rhs_type.get_id()
            ))
            .with_annotation(Annotation::primary(binary.lhs.span()).with_message("This is an array"))
            .with_annotation(Annotation::secondary(binary.rhs.span()).with_message(format!("This has type `{}`", rhs_type.get_id())))
            .with_note("PHP compares arrays as greater than other types (except other arrays and null). This might not be the intended comparison.")
            .with_help("Ensure both operands are of comparable types or explicitly cast/convert them before comparison."),
        );
    } else if !lhs_has_array && rhs_is_only_array && !lhs_type.is_null() {
        context.collector.report_with_code(
            IssueCode::InvalidOperand,
            Issue::error(format!(
                "Comparing a non-array type `{}` with an `array` using `<=>`.",
                lhs_type.get_id()
            ))
            .with_annotation(Annotation::primary(binary.lhs.span()).with_message(format!("This has type `{}`", lhs_type.get_id())))
            .with_annotation(Annotation::secondary(binary.rhs.span()).with_message("This is an array"))
            .with_note("PHP compares arrays as greater than other types (except other arrays and null). This might not be the intended comparison.")
            .with_help("Ensure both operands are of comparable types or explicitly cast/convert them before comparison."),
        );
    } else if lhs_has_array && !rhs_has_array && !rhs_type.is_null() {
        context.collector.report_with_code(
            IssueCode::PossiblyInvalidOperand,
            Issue::warning(format!(
                "Left operand may be an `array` when compared with non-array type `{}` using `<=>`.",
                rhs_type.get_id()
            ))
            .with_annotation(Annotation::primary(binary.lhs.span()).with_message(format!("This may be an array (type `{}`)", lhs_type.get_id())))
            .with_annotation(Annotation::secondary(binary.rhs.span()).with_message(format!("This has type `{}`", rhs_type.get_id())))
            .with_note("PHP compares arrays as greater than other types (except other arrays and null), so the spaceship result depends on which variant of the union the array side resolves to at runtime.")
            .with_help("Narrow the array side to a non-array type before comparing, or handle the array case separately."),
        );
    } else if !lhs_has_array && rhs_has_array && !lhs_type.is_null() {
        context.collector.report_with_code(
            IssueCode::PossiblyInvalidOperand,
            Issue::warning(format!(
                "Right operand may be an `array` when compared with non-array type `{}` using `<=>`.",
                lhs_type.get_id()
            ))
            .with_annotation(Annotation::primary(binary.lhs.span()).with_message(format!("This has type `{}`", lhs_type.get_id())))
            .with_annotation(Annotation::secondary(binary.rhs.span()).with_message(format!("This may be an array (type `{}`)", rhs_type.get_id())))
            .with_note("PHP compares arrays as greater than other types (except other arrays and null), so the spaceship result depends on which variant of the union the array side resolves to at runtime.")
            .with_help("Narrow the array side to a non-array type before comparing, or handle the array case separately."),
        );
    } else {
        // both sides have array variants or neither does. no array/non-array mismatch
    }

    let result_type = if !block_context.flags.inside_loop_expressions() && is_always_greater_than(lhs_type, rhs_type) {
        context.collector.report_with_code(
            IssueCode::RedundantTypeComparison,
            Issue::help("Redundant spaceship comparison: left-hand side is always greater than right-hand side.")
                .with_annotation(Annotation::primary(binary.lhs.span()).with_message("This is always greater"))
                .with_annotation(Annotation::secondary(binary.rhs.span()).with_message("This is always less"))
                .with_note("The spaceship operator `<=>` will always return `1` in this case.")
                .with_help("Consider removing this comparison. It will always evaluate to `1`."),
        );

        get_one_int()
    } else if !block_context.flags.inside_loop_expressions() && is_always_identical_to(lhs_type, rhs_type) {
        context.collector.report_with_code(
            IssueCode::RedundantTypeComparison,
            Issue::help("Redundant spaceship comparison: left-hand side is always equal to right-hand side.")
                .with_annotation(Annotation::primary(binary.lhs.span()).with_message("This is always equal"))
                .with_annotation(Annotation::secondary(binary.rhs.span()).with_message("This is always equal"))
                .with_note("The spaceship operator `<=>` will always return `0` in this case.")
                .with_help("Consider removing this comparison. It will always evaluate to `0`."),
        );

        get_zero_int()
    } else if !block_context.flags.inside_loop_expressions() && is_always_less_than(lhs_type, rhs_type) {
        context.collector.report_with_code(
            IssueCode::RedundantTypeComparison,
            Issue::help("Redundant spaceship comparison: left-hand side is always less than right-hand side.")
                .with_annotation(Annotation::primary(binary.lhs.span()).with_message("This is always less"))
                .with_annotation(Annotation::secondary(binary.rhs.span()).with_message("This is always greater"))
                .with_note("The spaceship operator `<=>` will always return `-1` in this case.")
                .with_help("Consider removing this comparison. It will always evaluate to `-1`."),
        );

        get_minus_one_int()
    } else {
        get_signum_result()
    };

    artifacts.expression_types.insert(get_expression_range(binary), Rc::new(result_type));

    Ok(())
}

fn check_spaceship_operand<'arena, A>(
    context: &mut Context<'_, 'arena, A>,
    operand: &Expression<'arena>,
    operand_type: &TUnion,
    side: &'static str,
) where
    A: Arena,
{
    if operand_type.is_null() {
        context.collector.report_with_code(
             IssueCode::NullOperand,
             Issue::error(format!(
                 "{side} operand in spaceship comparison (`<=>`) is `null`."
             ))
             .with_annotation(Annotation::primary(operand.span()).with_message("This is `null`"))
             .with_note("PHP compares `null` with other types according to specific rules (e.g., `null == 0` is true, `null < 1` is true).")
             .with_help("Ensure this comparison with `null` is intended, or provide a non-null operand."),
         );
    } else if operand_type.can_be_null() && !operand_type.is_mixed() {
        context.collector.report_with_code(
            IssueCode::PossiblyNullOperand,
            Issue::warning(format!(
                "{side} operand in spaceship comparison (`<=>`) might be `null` (type `{}`).",
                operand_type.get_id()
            ))
            .with_annotation(Annotation::primary(operand.span()).with_message("This might be `null`"))
            .with_note("If this operand is `null` at runtime, PHP's specific comparison rules for `null` will apply.")
            .with_help("Ensure this operand is non-null or that comparison with `null` is intended."),
        );
    } else if operand_type.is_mixed() {
        context.collector.report_with_code(
            IssueCode::MixedOperand,
            Issue::error(format!("{side} operand in spaceship comparison (`<=>`) has `mixed` type."))
                .with_annotation(Annotation::primary(operand.span()).with_message("This has type `mixed`"))
                .with_note("The result of comparing `mixed` types with `<=>` is unpredictable.")
                .with_help("Ensure this operand has a known, comparable type before using the spaceship operator."),
        );
    } else if operand_type.is_false() {
        context.collector.report_with_code(
            IssueCode::FalseOperand,
            Issue::error(format!(
                "{side} operand in spaceship comparison (`<=>`) is `false`."
            ))
            .with_annotation(Annotation::primary(operand.span()).with_message("This is `false`"))
            .with_note("PHP compares `false` with other types according to specific rules (e.g., `false == 0` is true, `false < 1` is true).")
            .with_help("Ensure this comparison with `false` is intended, or provide a non-false operand."),
        );
    } else if operand_type.is_falsable() && !operand_type.ignore_falsable_issues() {
        context.collector.report_with_code(
            IssueCode::PossiblyFalseOperand,
            Issue::warning(format!(
                "{side} operand in spaceship comparison (`<=>`) might be `false` (type `{}`).",
                operand_type.get_id()
            ))
            .with_annotation(Annotation::primary(operand.span()).with_message("This might be `false`"))
            .with_note("If this operand is `false` at runtime, PHP's specific comparison rules for `false` will apply.")
            .with_help("Ensure this operand is non-false or that comparison with `false` is intended."),
        );
    } else {
        // operand isn't null/mixed/false-bearing; no spaceship-operand diagnostic to emit
    }
}