Introduce CFGImplicitDtor::isNoReturn() to query whether a destructor actually returns. Use this for -Wreturn-type to prune false positives reported in PR 6884.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@126875 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 49 insertions, 1 deletions

diff --git a/lib/Analysis/CFG.cpp b/lib/Analysis/CFG.cpp
index 1357653934..2818cf6d62 100644
--- a/lib/Analysis/CFG.cpp
+++ b/lib/Analysis/CFG.cpp
@@ -2773,7 +2773,40 @@ CFG* CFG::buildCFG(const Decl *D, Stmt* Statement, ASTContext *C,
 }
 
 const CXXDestructorDecl *CFGImplicitDtor::getDestructorDecl() const {
-  return 0;
+  switch (getKind()) {
+    case CFGElement::Invalid:
+    case CFGElement::Statement:
+    case CFGElement::Initializer:
+      llvm_unreachable("getDestructorDecl should only be used with "
+                       "ImplicitDtors");
+    case CFGElement::AutomaticObjectDtor: {
+      const VarDecl *var = cast<CFGAutomaticObjDtor>(this)->getVarDecl();
+      QualType ty = var->getType();
+      const RecordType *recordType = ty->getAs<RecordType>();
+      const CXXRecordDecl *classDecl =
+        cast<CXXRecordDecl>(recordType->getDecl());
+      return classDecl->getDestructor();      
+    }
+    case CFGElement::TemporaryDtor: {
+      const CXXBindTemporaryExpr *bindExpr =
+        cast<CFGTemporaryDtor>(this)->getBindTemporaryExpr();
+      const CXXTemporary *temp = bindExpr->getTemporary();
+      return temp->getDestructor();
+    }
+    case CFGElement::BaseDtor:
+    case CFGElement::MemberDtor:
+
+      // Not yet supported.
+      return 0;
+  }
+}
+
+bool CFGImplicitDtor::isNoReturn() const {
+  if (const CXXDestructorDecl *cdecl = getDestructorDecl()) {
+    QualType ty = cdecl->getType();
+    return cast<FunctionType>(ty)->getNoReturnAttr();
+  }
+  return false;
 }
 
 //===----------------------------------------------------------------------===//
diff --git a/lib/Sema/AnalysisBasedWarnings.cpp b/lib/Sema/AnalysisBasedWarnings.cpp
index 6a422242a9..84efbd50d1 100644
--- a/lib/Sema/AnalysisBasedWarnings.cpp
+++ b/lib/Sema/AnalysisBasedWarnings.cpp
@@ -129,12 +129,27 @@ static ControlFlowKind CheckFallThrough(AnalysisContext &AC) {
     // normal.  We need to look pass the destructors for the return
     // statement (if it exists).
     CFGBlock::const_reverse_iterator ri = B.rbegin(), re = B.rend();
+    bool hasNoReturnDtor = false;
+    
     for ( ; ri != re ; ++ri) {
       CFGElement CE = *ri;
+
+      // FIXME: The right solution is to just sever the edges in the
+      // CFG itself.
+      if (const CFGImplicitDtor *iDtor = ri->getAs<CFGImplicitDtor>())
+        if (iDtor->isNoReturn()) {
+          hasNoReturnDtor = true;
+          HasFakeEdge = true;
+          break;
+        }
+      
       if (isa<CFGStmt>(CE))
         break;
     }
     
+    if (hasNoReturnDtor)
+      continue;
+    
     // No more CFGElements in the block?
     if (ri == re) {
       if (B.getTerminator() && isa<CXXTryStmt>(B.getTerminator())) {