[Sema] Suppress warnings for C's zero initializer

Patch by S. Gilles!

Differential Revision: https://reviews.llvm.org/D28148

llvm-svn: 314499

2 files changed, 16 insertions, 2 deletions

diff --git a/clang/lib/AST/Expr.cpp b/clang/lib/AST/Expr.cpp
index aab89d392dc..9181176bbd9 100644
--- a/clang/lib/AST/Expr.cpp
+++ b/clang/lib/AST/Expr.cpp
@@ -1951,6 +1951,17 @@ bool InitListExpr::isTransparent() const {
          getInit(0)->getType().getCanonicalType();
 }
 
+bool InitListExpr::isIdiomaticZeroInitializer(const LangOptions &LangOpts) const {
+  assert(isSyntacticForm() && "only test syntactic form as zero initializer");
+
+  if (LangOpts.CPlusPlus || getNumInits() != 1) {
+    return false;
+  }
+
+  const IntegerLiteral *Lit = dyn_cast<IntegerLiteral>(getInit(0));
+  return Lit && Lit->getValue() == 0;
+}
+
 SourceLocation InitListExpr::getLocStart() const {
   if (InitListExpr *SyntacticForm = getSyntacticForm())
     return SyntacticForm->getLocStart();
diff --git a/clang/lib/Sema/SemaInit.cpp b/clang/lib/Sema/SemaInit.cpp
index 59ec9e28516..341e7120fe8 100644
--- a/clang/lib/Sema/SemaInit.cpp
+++ b/clang/lib/Sema/SemaInit.cpp
@@ -886,7 +886,8 @@ void InitListChecker::CheckImplicitInitList(const InitializedEntity &Entity,
     }
 
     // Complain about missing braces.
-    if (T->isArrayType() || T->isRecordType()) {
+    if ((T->isArrayType() || T->isRecordType()) &&
+        !ParentIList->isIdiomaticZeroInitializer(SemaRef.getLangOpts())) {
       SemaRef.Diag(StructuredSubobjectInitList->getLocStart(),
                    diag::warn_missing_braces)
           << StructuredSubobjectInitList->getSourceRange()
@@ -1833,7 +1834,9 @@ void InitListChecker::CheckStructUnionTypes(
   // worthwhile to skip over the rest of the initializer, though.
   RecordDecl *RD = DeclType->getAs<RecordType>()->getDecl();
   RecordDecl::field_iterator FieldEnd = RD->field_end();
-  bool CheckForMissingFields = true;
+  bool CheckForMissingFields =
+    !IList->isIdiomaticZeroInitializer(SemaRef.getLangOpts());
+
   while (Index < IList->getNumInits()) {
     Expr *Init = IList->getInit(Index);