From 87af5f5b44d93a989ba9e55c738c38f69a41121f Mon Sep 17 00:00:00 2001 From: Olivier Goffart Date: Sun, 30 Nov 2025 17:02:07 +0100 Subject: [PATCH] Supress some lookup errors if a module contains `compile_error!` The problem is that when a macro expand to `compile_error!` because its input is malformed, the actual error message from the `compile_error!` might be hidden in a long list of other messages about using items that should have otherwise been generated by the macro. So suppress error about missing items in that module. --- .../rustc_builtin_macros/src/compile_error.rs | 1 + compiler/rustc_expand/src/base.rs | 4 +++ compiler/rustc_resolve/src/ident.rs | 3 +- compiler/rustc_resolve/src/macros.rs | 6 ++++ .../compile_error_macro-suppress-errors.rs | 25 +++++++++++++++++ ...compile_error_macro-suppress-errors.stderr | 28 +++++++++++++++++++ 6 files changed, 66 insertions(+), 1 deletion(-) create mode 100644 tests/ui/macros/compile_error_macro-suppress-errors.rs create mode 100644 tests/ui/macros/compile_error_macro-suppress-errors.stderr diff --git a/compiler/rustc_builtin_macros/src/compile_error.rs b/compiler/rustc_builtin_macros/src/compile_error.rs index 7fc4b437c1d8d..df64d8f314dba 100644 --- a/compiler/rustc_builtin_macros/src/compile_error.rs +++ b/compiler/rustc_builtin_macros/src/compile_error.rs @@ -22,6 +22,7 @@ pub(crate) fn expand_compile_error<'cx>( #[expect(rustc::diagnostic_outside_of_impl, reason = "diagnostic message is specified by user")] #[expect(rustc::untranslatable_diagnostic, reason = "diagnostic message is specified by user")] let guar = cx.dcx().span_err(sp, var.to_string()); + cx.resolver.mark_scope_with_compile_error(cx.current_expansion.lint_node_id); ExpandResult::Ready(DummyResult::any(sp, guar)) } diff --git a/compiler/rustc_expand/src/base.rs b/compiler/rustc_expand/src/base.rs index 946f17943fe3d..68d9a1db64d2f 100644 --- a/compiler/rustc_expand/src/base.rs +++ b/compiler/rustc_expand/src/base.rs @@ -1200,6 +1200,10 @@ pub trait ResolverExpand { /// Record the name of an opaque `Ty::ImplTrait` pre-expansion so that it can be used /// to generate an item name later that does not reference placeholder macros. fn insert_impl_trait_name(&mut self, id: NodeId, name: Symbol); + + /// Mark the scope as having a compile error so that error for lookup in this scope + /// should be suppressed + fn mark_scope_with_compile_error(&mut self, parent_node: NodeId); } pub trait LintStoreExpand { diff --git a/compiler/rustc_resolve/src/ident.rs b/compiler/rustc_resolve/src/ident.rs index f59b5a0aad9a7..464540b42cd6d 100644 --- a/compiler/rustc_resolve/src/ident.rs +++ b/compiler/rustc_resolve/src/ident.rs @@ -1718,7 +1718,8 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> { diag_metadata: Option<&DiagMetadata<'_>>, ) -> PathResult<'ra> { let mut module = None; - let mut module_had_parse_errors = false; + let mut module_had_parse_errors = !self.mods_with_parse_errors.is_empty() + && self.mods_with_parse_errors.contains(&parent_scope.module.nearest_parent_mod()); let mut allow_super = true; let mut second_binding = None; diff --git a/compiler/rustc_resolve/src/macros.rs b/compiler/rustc_resolve/src/macros.rs index 1222b40d8b367..56b44e4c6d786 100644 --- a/compiler/rustc_resolve/src/macros.rs +++ b/compiler/rustc_resolve/src/macros.rs @@ -167,6 +167,12 @@ impl<'ra, 'tcx> ResolverExpand for Resolver<'ra, 'tcx> { self.invocation_parents[&id].parent_def } + fn mark_scope_with_compile_error(&mut self, id: NodeId) { + if let Some(id) = self.opt_local_def_id(id) { + self.mods_with_parse_errors.insert(id.to_def_id()); + } + } + fn resolve_dollar_crates(&self) { hygiene::update_dollar_crate_names(|ctxt| { let ident = Ident::new(kw::DollarCrate, DUMMY_SP.with_ctxt(ctxt)); diff --git a/tests/ui/macros/compile_error_macro-suppress-errors.rs b/tests/ui/macros/compile_error_macro-suppress-errors.rs new file mode 100644 index 0000000000000..f6f703dd3916d --- /dev/null +++ b/tests/ui/macros/compile_error_macro-suppress-errors.rs @@ -0,0 +1,25 @@ +mod some_module { + compile_error!("Error in a module"); //~ ERROR: Error in a module + + fn abc() { + let _: self::SomeType = self::Hello::new(); + let _: SomeType = Hello::new(); + } +} + +mod another_module {} + +fn main() { + // these errors are suppressed because of the compile_error! macro + + let _ = some_module::some_function(); + let _: some_module::SomeType = some_module::Hello::new(); + + // these errors are not suppressed + + let _ = another_module::some_function(); + //~^ ERROR: cannot find function `some_function` in module `another_module` + let _: another_module::SomeType = another_module::Hello::new(); + //~^ ERROR: cannot find type `SomeType` in module `another_module` + //~^^ ERROR: failed to resolve: could not find `Hello` in `another_module` +} diff --git a/tests/ui/macros/compile_error_macro-suppress-errors.stderr b/tests/ui/macros/compile_error_macro-suppress-errors.stderr new file mode 100644 index 0000000000000..292b5fef248a0 --- /dev/null +++ b/tests/ui/macros/compile_error_macro-suppress-errors.stderr @@ -0,0 +1,28 @@ +error: Error in a module + --> $DIR/compile_error_macro-suppress-errors.rs:2:5 + | +LL | compile_error!("Error in a module"); + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +error[E0433]: failed to resolve: could not find `Hello` in `another_module` + --> $DIR/compile_error_macro-suppress-errors.rs:22:55 + | +LL | let _: another_module::SomeType = another_module::Hello::new(); + | ^^^^^ could not find `Hello` in `another_module` + +error[E0425]: cannot find function `some_function` in module `another_module` + --> $DIR/compile_error_macro-suppress-errors.rs:20:29 + | +LL | let _ = another_module::some_function(); + | ^^^^^^^^^^^^^ not found in `another_module` + +error[E0412]: cannot find type `SomeType` in module `another_module` + --> $DIR/compile_error_macro-suppress-errors.rs:22:28 + | +LL | let _: another_module::SomeType = another_module::Hello::new(); + | ^^^^^^^^ not found in `another_module` + +error: aborting due to 4 previous errors + +Some errors have detailed explanations: E0412, E0425, E0433. +For more information about an error, try `rustc --explain E0412`.