Rollup merge of #141934 - petrochenkov:privmacuse, r=compiler-errors

resolve: Tweak `private_macro_use` lint to be compatible with upcoming macro prelude changes

Unblocks https://github.com/rust-lang/rust/pull/139493.
Zulip thread requesting help - [#t-compiler/help > Help requested for effects of #139493](https://rust-lang.zulipchat.com/#narrow/channel/182449-t-compiler.2Fhelp/topic/Help.20requested.20for.20effects.20of.20.23139493/with/514653911).

This PR by itself shouldn't cause any observable changes, its only observable effect is that the prelude changes from https://github.com/rust-lang/rust/pull/139493 will no longer cause regressions in tests like `tests/ui/imports/issue-119369.rs` or `tests/ui/extern/issue-80074.rs`.

This is achieved by moving the "is this thing in stdlib prelude" check from an early point (`fn process_macro_use_imports`) to a later point (`fn record_use_inner`), at which the stdlib prelude is already populated and can be inspected.
(The `is_builtin_macro` check is subsumed by the stdlib prelude check, all built-in macros go through the stdlib prelude anyway.)

3 files changed, 36 insertions, 22 deletions

diff --git a/compiler/rustc_resolve/src/build_reduced_graph.rs b/compiler/rustc_resolve/src/build_reduced_graph.rs
index c30ed781f35..650a827ba56 100644
--- a/compiler/rustc_resolve/src/build_reduced_graph.rs
+++ b/compiler/rustc_resolve/src/build_reduced_graph.rs
@@ -1098,22 +1098,20 @@ impl<'a, 'ra, 'tcx> BuildReducedGraphVisitor<'a, 'ra, 'tcx> {
             self.r.potentially_unused_imports.push(import);
             module.for_each_child(self, |this, ident, ns, binding| {
                 if ns == MacroNS {
-                    let imported_binding =
-                        if this.r.is_accessible_from(binding.vis, this.parent_scope.module) {
-                            this.r.import(binding, import)
-                        } else if !this.r.is_builtin_macro(binding.res())
-                            && !this.r.macro_use_prelude.contains_key(&ident.name)
-                        {
-                            // - `!r.is_builtin_macro(res)` excluding the built-in macros such as `Debug` or `Hash`.
-                            // - `!r.macro_use_prelude.contains_key(name)` excluding macros defined in other extern
-                            //    crates such as `std`.
-                            // FIXME: This branch should eventually be removed.
-                            let import = macro_use_import(this, span, true);
-                            this.r.import(binding, import)
-                        } else {
+                    let import = if this.r.is_accessible_from(binding.vis, this.parent_scope.module)
+                    {
+                        import
+                    } else {
+                        // FIXME: This branch is used for reporting the `private_macro_use` lint
+                        // and should eventually be removed.
+                        if this.r.macro_use_prelude.contains_key(&ident.name) {
+                            // Do not override already existing entries with compatibility entries.
                             return;
-                        };
-                    this.add_macro_use_binding(ident.name, imported_binding, span, allow_shadowing);
+                        }
+                        macro_use_import(this, span, true)
+                    };
+                    let import_binding = this.r.import(binding, import);
+                    this.add_macro_use_binding(ident.name, import_binding, span, allow_shadowing);
                 }
             });
         } else {
diff --git a/compiler/rustc_resolve/src/imports.rs b/compiler/rustc_resolve/src/imports.rs
index 816efd0d5fa..e989209e177 100644
--- a/compiler/rustc_resolve/src/imports.rs
+++ b/compiler/rustc_resolve/src/imports.rs
@@ -133,7 +133,9 @@ impl<'ra> std::fmt::Debug for ImportKind<'ra> {
                 .field("target", target)
                 .field("id", id)
                 .finish(),
-            MacroUse { .. } => f.debug_struct("MacroUse").finish(),
+            MacroUse { warn_private } => {
+                f.debug_struct("MacroUse").field("warn_private", warn_private).finish()
+            }
             MacroExport => f.debug_struct("MacroExport").finish(),
         }
     }
diff --git a/compiler/rustc_resolve/src/lib.rs b/compiler/rustc_resolve/src/lib.rs
index 9ba70abd4d9..ea8715b8254 100644
--- a/compiler/rustc_resolve/src/lib.rs
+++ b/compiler/rustc_resolve/src/lib.rs
@@ -1934,12 +1934,26 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
         }
         if let NameBindingKind::Import { import, binding } = used_binding.kind {
             if let ImportKind::MacroUse { warn_private: true } = import.kind {
-                self.lint_buffer().buffer_lint(
-                    PRIVATE_MACRO_USE,
-                    import.root_id,
-                    ident.span,
-                    BuiltinLintDiag::MacroIsPrivate(ident),
-                );
+                // Do not report the lint if the macro name resolves in stdlib prelude
+                // even without the problematic `macro_use` import.
+                let found_in_stdlib_prelude = self.prelude.is_some_and(|prelude| {
+                    self.maybe_resolve_ident_in_module(
+                        ModuleOrUniformRoot::Module(prelude),
+                        ident,
+                        MacroNS,
+                        &ParentScope::module(self.empty_module, self),
+                        None,
+                    )
+                    .is_ok()
+                });
+                if !found_in_stdlib_prelude {
+                    self.lint_buffer().buffer_lint(
+                        PRIVATE_MACRO_USE,
+                        import.root_id,
+                        ident.span,
+                        BuiltinLintDiag::MacroIsPrivate(ident),
+                    );
+                }
             }
             // Avoid marking `extern crate` items that refer to a name from extern prelude,
             // but not introduce it, as used if they are accessed from lexical scope.