[modules] Fix Decl's Used invariant.
The Decl::isUsed has a value for every decl. In non-module builds it is very
difficult (but possible) to break this invariant but when we walk up the redecl
chain we find the neccessary information.
When deserializing the decls from a module it is much more difficult to update
correctly this invariant. The patch centralizes the information whether a decl
is used in the canonical decl marking the entire entity as being used.
Fixes https://llvm.org/bugs/show_bug.cgi?id=27401
Patch by Cristina Cristescu and me.
Thanks to Richard Smith who helped to debug and understand the issue!
Reviewed by Richard Smith.
llvm-svn: 267691
diff --git a/clang/lib/AST/DeclBase.cpp b/clang/lib/AST/DeclBase.cpp
index aec3b7c..338b059 100644
--- a/clang/lib/AST/DeclBase.cpp
+++ b/clang/lib/AST/DeclBase.cpp
@@ -340,25 +340,29 @@
return Align;
}
-bool Decl::isUsed(bool CheckUsedAttr) const {
- if (Used)
- return true;
-
- // Check for used attribute.
- if (CheckUsedAttr && hasAttr<UsedAttr>())
+bool Decl::isUsed(bool CheckUsedAttr) const {
+ const Decl *CanonD = getCanonicalDecl();
+ if (CanonD->Used)
return true;
- return false;
+ // Check for used attribute.
+ // Ask the most recent decl, since attributes accumulate in the redecl chain.
+ if (CheckUsedAttr && getMostRecentDecl()->hasAttr<UsedAttr>())
+ return true;
+
+ // The information may have not been deserialized yet. Force deserialization
+ // to complete the needed information.
+ return getMostRecentDecl()->getCanonicalDecl()->Used;
}
void Decl::markUsed(ASTContext &C) {
- if (Used)
+ if (isUsed())
return;
if (C.getASTMutationListener())
C.getASTMutationListener()->DeclarationMarkedUsed(this);
- Used = true;
+ setIsUsed();
}
bool Decl::isReferenced() const {