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Addresses Rust-GCC#4409. Validate duplicate matcher bindings for `macro_rules!` during definition resolution so duplicates are diagnosed even if the macro is never invoked. gcc/rust/ChangeLog: * expand/rust-macro-expand.cc (MacroExpander::expand_decl_macro): Always emit the failed-to-match error when no rule matches. (MacroExpander::match_matcher): Remove duplicate-binding checks. * expand/rust-macro-expand.h (MacroExpander): Remove had_duplicate_error state. * resolve/rust-early-name-resolver-2.0.cc (check_matcher_for_duplicate_bindings): New helper. (Early::visit): Check for duplicate matcher bindings in macro definitions. gcc/testsuite/ChangeLog: * rust/compile/macros/mbe/macro-duplicate-binding.rs: Check duplicate matcher bindings on an unused macro definition.
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Feb 23, 2026
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Some files are artifacts generated from the configure script and should not be pushed.
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ok let me update the PR |
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@hriztam changes to the .gitignore that are due to your personal setup shouldn't be pushed :) also the testsuite is failing in the CI, please make sure it passes before we can merge this. Finally before merging you'll need to squash your commits that add and remove the generated files. thanks! |
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Addresses #4409.
This change moves duplicate matcher binding validation for
macro_rules!from invocation-time matching into macro-definition validation during early name resolution. This makes duplicate metavariable bindings fail even when the macro is never invoked, matching rustc’s behavior forduplicate matcher binding.It also adds an unused macro-definition warning pass in expansion by scanning AST macro definitions and checking whether each definition is referenced by a resolved invocation (excluding builtins and
#[macro_export]cases), producingunused macro definition.The expander-side duplicate-binding guard logic was removed since diagnostics are now emitted at definition validation time.
Tests:
gcc/testsuite/rust/compile/macros/mbe/macro-duplicate-binding.rsto cover the uninvoked reproducer and assert both:duplicate matcher bindingerrorunused macro definitionwarningAlso I tried to format the code using clang-format but that resulted in a much larger pr with a lot of files formatted at once, so I reverted it for the time being. Let me know if that is something which is needed
Signed-off-by: Hritam Shrivastava hritamstark05@gmail.com