[Sema] Make getCurFunction() return null outside function parsing

Summary:
Before this patch, Sema pre-allocated a FunctionScopeInfo and kept it in
the first, always present element of the FunctionScopes stack. This
meant that Sema::getCurFunction would return a pointer to this
pre-allocated object when parsing code outside a function body. This is
pretty much always a bug, so this patch moves the pre-allocated object
into a separate unique_ptr. This should make bugs like PR36536 a lot
more obvious.

As you can see from this patch, there were a number of places that
unconditionally assumed they were always called inside a function.
However, there are also many places that null checked the result of
getCurFunction(), so I think this is a reasonable direction.

Reviewers: rsmith

Subscribers: cfe-commits

Differential Revision: https://reviews.llvm.org/D44039

llvm-svn: 326965

1 files changed, 11 insertions, 10 deletions

diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
index 036082c9412..6d7dc677f1c 100644
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -5747,7 +5747,7 @@ Sema::CheckTypedefForVariablyModifiedType(Scope *S, TypedefNameDecl *NewTD) {
   TypeSourceInfo *TInfo = NewTD->getTypeSourceInfo();
   QualType T = TInfo->getType();
   if (T->isVariablyModifiedType()) {
-    getCurFunction()->setHasBranchProtectedScope();
+    setFunctionHasBranchProtectedScope();
 
     if (S->getFnParent() == nullptr) {
       bool SizeIsNegative;
@@ -7407,7 +7407,7 @@ void Sema::CheckVariableDeclarationType(VarDecl *NewVD) {
   bool isVM = T->isVariablyModifiedType();
   if (isVM || NewVD->hasAttr<CleanupAttr>() ||
       NewVD->hasAttr<BlocksAttr>())
-    getCurFunction()->setHasBranchProtectedScope();
+    setFunctionHasBranchProtectedScope();
 
   if ((isVM && NewVD->hasLinkage()) ||
       (T->isVariableArrayType() && NewVD->hasGlobalStorage())) {
@@ -10644,7 +10644,7 @@ void Sema::AddInitializerToDecl(Decl *RealDecl, Expr *Init, bool DirectInit) {
     }
 
     if (VDecl->hasLocalStorage())
-      getCurFunction()->setHasBranchProtectedScope();
+      setFunctionHasBranchProtectedScope();
 
     if (DiagnoseUnexpandedParameterPack(Init, UPPC_Initializer)) {
       VDecl->setInvalidDecl();
@@ -11178,11 +11178,11 @@ void Sema::ActOnUninitializedDecl(Decl *RealDecl) {
       if (const RecordType *Record
             = Context.getBaseElementType(Type)->getAs<RecordType>()) {
         CXXRecordDecl *CXXRecord = cast<CXXRecordDecl>(Record->getDecl());
-        // Mark the function for further checking even if the looser rules of
-        // C++11 do not require such checks, so that we can diagnose
-        // incompatibilities with C++98.
+        // Mark the function (if we're in one) for further checking even if the
+        // looser rules of C++11 do not require such checks, so that we can
+        // diagnose incompatibilities with C++98.
         if (!CXXRecord->isPOD())
-          getCurFunction()->setHasBranchProtectedScope();
+          setFunctionHasBranchProtectedScope();
       }
     }
 
@@ -11318,13 +11318,14 @@ void Sema::CheckCompleteVariableDeclaration(VarDecl *var) {
 
     case Qualifiers::OCL_Weak:
     case Qualifiers::OCL_Strong:
-      getCurFunction()->setHasBranchProtectedScope();
+      setFunctionHasBranchProtectedScope();
       break;
     }
   }
 
-  if (var->getType().isDestructedType() == QualType::DK_nontrivial_c_struct)
-    getCurFunction()->setHasBranchProtectedScope();
+  if (var->hasLocalStorage() &&
+      var->getType().isDestructedType() == QualType::DK_nontrivial_c_struct)
+    setFunctionHasBranchProtectedScope();
 
   // Warn about externally-visible variables being defined without a
   // prior declaration.  We only want to do this for global