[modules] Handle friend function that was a definition but became only a declaration during AST deserialization (#132214)

Fix for regression #130917, changes in #111992 were too broad. This change reduces scope of previous fix. Added `ExternalASTSource::wasThisDeclarationADefinition` to detect cases when FunctionDecl lost body due to declaration merges.

1 files changed, 8 insertions, 0 deletions

diff --git a/clang/lib/Sema/MultiplexExternalSemaSource.cpp b/clang/lib/Sema/MultiplexExternalSemaSource.cpp
index 6d94530..fbfb242 100644
--- a/clang/lib/Sema/MultiplexExternalSemaSource.cpp
+++ b/clang/lib/Sema/MultiplexExternalSemaSource.cpp
@@ -107,6 +107,14 @@ MultiplexExternalSemaSource::hasExternalDefinitions(const Decl *D) {
   return EK_ReplyHazy;
 }
 
+bool MultiplexExternalSemaSource::wasThisDeclarationADefinition(
+    const FunctionDecl *FD) {
+  for (const auto &S : Sources)
+    if (S->wasThisDeclarationADefinition(FD))
+      return true;
+  return false;
+}
+
 bool MultiplexExternalSemaSource::FindExternalVisibleDeclsByName(
     const DeclContext *DC, DeclarationName Name,
     const DeclContext *OriginalDC) {