[PATCH] D114833: [modules] Fix ambiguous name lookup for enum constants from hidden submodules.

[Volodymyr Sapsai via Phabricator via cfe-commits]

vsapsai updated this revision to Diff 391189.
vsapsai added a comment.

Attempt to restore a previous commit.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D114833/new/

https://reviews.llvm.org/D114833

Files:
  clang/lib/Sema/SemaDecl.cpp
  clang/test/Modules/ambiguous-anonymous-enum-lookup.cpp
  clang/test/Modules/redefinition-c-tagtypes.m


Index: clang/test/Modules/redefinition-c-tagtypes.m
===================================================================
--- clang/test/Modules/redefinition-c-tagtypes.m
+++ clang/test/Modules/redefinition-c-tagtypes.m
@@ -32,6 +32,10 @@
   TRD = 55
 };
 
+int testReferencingNSEConstant() {
+  return FST;
+}
+
 #define NS_ENUM(_type, _name) \
   enum _name : _type _name;   \
   enum _name : _type
@@ -42,7 +46,11 @@
   MinXOther = MinX,
 #else
   MinXOther = TRD, // expected-note {{enumerator 'MinXOther' with value 55 here}}
-  // expected-error at redefinition-c-tagtypes.m:39 {{type 'enum NSMyEnum' has incompatible definitions}}
+  // expected-error at redefinition-c-tagtypes.m:43 {{type 'enum NSMyEnum' has incompatible definitions}}
   // expected-note at Inputs/F.framework/PrivateHeaders/NS.h:18 {{enumerator 'MinXOther' with value 11 here}}
 #endif
 };
+
+int testReferencingNSMyEnumConstant() {
+  return MinX;
+}
Index: clang/test/Modules/ambiguous-anonymous-enum-lookup.cpp
===================================================================
--- /dev/null
+++ clang/test/Modules/ambiguous-anonymous-enum-lookup.cpp
@@ -0,0 +1,41 @@
+// RUN: rm -rf %t
+// RUN: split-file %s %t
+// RUN: %clang_cc1 -fsyntax-only -fmodules -fimplicit-module-maps -fmodules-cache-path=%t/modules.cache -I %t/include %t/test.cpp -verify
+
+//--- include/textual.h
+#ifndef TEXTUAL_H
+#define TEXTUAL_H
+
+enum {
+  kAnonymousEnumValue = 0,
+};
+
+#endif
+
+//--- include/empty.h
+// empty
+
+//--- include/initially_hidden.h
+#include <textual.h>
+
+//--- include/module.modulemap
+module Piecewise {
+  module Empty {
+    header "empty.h"
+    export *
+  }
+  module InitiallyHidden {
+    header "initially_hidden.h"
+    export *
+  }
+}
+
+//--- test.cpp
+#include <empty.h>
+#include <textual.h>
+#include <initially_hidden.h>
+
+// expected-no-diagnostics
+int testReferencingAnonymousEnumConstant() {
+  return kAnonymousEnumValue;
+}
Index: clang/lib/Sema/SemaDecl.cpp
===================================================================
--- clang/lib/Sema/SemaDecl.cpp
+++ clang/lib/Sema/SemaDecl.cpp
@@ -16598,6 +16598,19 @@
 
   // Make the previous decl visible.
   makeMergedDefinitionVisible(SkipBody.Previous);
+  // For the ignored `EnumDecl` definition remove its `EnumConstantDecl` from
+  // global name lookup to avoid future ambiguous lookups. Doing this for ObjC/C
+  // to mimic early return in `Sema::ActOnTag` that avoids calling
+  // `PushOnScopeChains` for duplicate `TagDecl` definitions. Doing it only for
+  // `EnumDecl` among all `TagDecl` because enum constants have global name
+  // lookup while record field lookup is limited to a record.
+  if (!getLangOpts().CPlusPlus) {
+    if (const auto *ED = dyn_cast<EnumDecl>(SkipBody.New))
+      for (EnumDecl::enumerator_iterator EC = ED->enumerator_begin(),
+                                         End = ED->enumerator_end();
+           EC != End; ++EC)
+        IdResolver.RemoveDecl(*EC);
+  }
   return true;
 }
 


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