Fix -Wdynamic-class-memaccess to skip invalid classes.

This warning sometimes will infinitely recurse on CXXRecordDecl's from
ill-formed recursive classes that have fields of themselves.  Skip processing
these classes to prevent this from happening.
Fixes https://llvm.org/bugs/show_bug.cgi?id=27142

llvm-svn: 264991

2 files changed, 14 insertions, 1 deletions

diff --git a/clang/lib/Sema/SemaChecking.cpp b/clang/lib/Sema/SemaChecking.cpp
index 43195bd64ff..ee39401d48a 100644
--- a/clang/lib/Sema/SemaChecking.cpp
+++ b/clang/lib/Sema/SemaChecking.cpp
@@ -5611,7 +5611,7 @@ static const CXXRecordDecl *getContainedDynamicClass(QualType T,
 
   const CXXRecordDecl *RD = Ty->getAsCXXRecordDecl();
   RD = RD ? RD->getDefinition() : nullptr;
-  if (!RD)
+  if (!RD || RD->isInvalidDecl())
     return nullptr;
 
   if (RD->isDynamicClass())
diff --git a/clang/test/SemaCXX/warn-bad-memaccess.cpp b/clang/test/SemaCXX/warn-bad-memaccess.cpp
index 67cde10bf45..55ce4a0da03 100644
--- a/clang/test/SemaCXX/warn-bad-memaccess.cpp
+++ b/clang/test/SemaCXX/warn-bad-memaccess.cpp
@@ -141,3 +141,16 @@ namespace N {
     N::memset(&x1, 0, sizeof x1);
   }
 }
+
+namespace recursive_class {
+struct S {
+  S v;
+  // expected-error@-1{{field has incomplete type 'recursive_class::S'}}
+  // expected-note@-3{{definition of 'recursive_class::S' is not complete until the closing '}'}}
+} a;
+
+int main() {
+  __builtin_memset(&a, 0, sizeof a);
+  return 0;
+}
+}