From: Anders Carlsson <andersca@mac.com>
Date: Fri, 30 Nov 2007 19:04:31 +0000 (+0000)
Subject: GCC has an extension where the left hand side of the ? : operator can be omitted... 
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=3907323dd6665c0c4e383435cb145233f4533406;p=clang

GCC has an extension where the left hand side of the ? : operator can be omitted. Handle this in a few more places.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@44462 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/AST/Expr.cpp b/AST/Expr.cpp
index 682b4bd92b..0aee702c65 100644
--- a/AST/Expr.cpp
+++ b/AST/Expr.cpp
@@ -494,7 +494,8 @@ bool Expr::isConstantExpr(ASTContext &Ctx, SourceLocation *Loc) const {
   case ConditionalOperatorClass: {
     const ConditionalOperator *Exp = cast<ConditionalOperator>(this);
     if (!Exp->getCond()->isConstantExpr(Ctx, Loc) ||
-        !Exp->getLHS()->isConstantExpr(Ctx, Loc) ||
+        // Handle the GNU extension for missing LHS.
+        !(Exp->getLHS() && Exp->getLHS()->isConstantExpr(Ctx, Loc)) ||
         !Exp->getRHS()->isConstantExpr(Ctx, Loc))
       return false;
     return true;
@@ -809,10 +810,11 @@ bool Expr::isIntegerConstantExpr(llvm::APSInt &Result, ASTContext &Ctx,
     if (Result == 0) std::swap(TrueExp, FalseExp);
     
     // Evaluate the false one first, discard the result.
-    if (!FalseExp->isIntegerConstantExpr(Result, Ctx, Loc, false))
+    if (FalseExp && !FalseExp->isIntegerConstantExpr(Result, Ctx, Loc, false))
       return false;
     // Evalute the true one, capture the result.
-    if (!TrueExp->isIntegerConstantExpr(Result, Ctx, Loc, isEvaluated))
+    if (TrueExp && 
+        !TrueExp->isIntegerConstantExpr(Result, Ctx, Loc, isEvaluated))
       return false;
     break;
   }
diff --git a/Analysis/UninitializedValues.cpp b/Analysis/UninitializedValues.cpp
index 8a27b71b8f..35d6124e62 100644
--- a/Analysis/UninitializedValues.cpp
+++ b/Analysis/UninitializedValues.cpp
@@ -145,7 +145,13 @@ bool TransferFuncs::VisitUnaryOperator(UnaryOperator* U) {
   
 bool TransferFuncs::VisitConditionalOperator(ConditionalOperator* C) {
   Visit(C->getCond());
-  return Visit(C->getLHS()) & Visit(C->getRHS());  // Yes: we want &, not &&.
+
+  bool rhsResult = Visit(C->getRHS());
+  // Handle the GNU extension for missing LHS.
+  if (Expr *lhs = C->getLHS())
+    return Visit(lhs) & rhsResult; // Yes: we want &, not &&.
+  else
+    return rhsResult;
 }
 
 bool TransferFuncs::VisitStmt(Stmt* S) {
diff --git a/Sema/SemaChecking.cpp b/Sema/SemaChecking.cpp
index 20f0b81b43..81a18c9645 100644
--- a/Sema/SemaChecking.cpp
+++ b/Sema/SemaChecking.cpp
@@ -564,10 +564,12 @@ static DeclRefExpr* EvalAddr(Expr *E) {
     case Stmt::ConditionalOperatorClass: {
       ConditionalOperator *C = cast<ConditionalOperator>(E);
       
-      if (DeclRefExpr* LHS = EvalAddr(C->getLHS()))
-        return LHS;
-      else
-        return EvalAddr(C->getRHS());
+      // Handle the GNU extension for missing LHS.
+      if (Expr *lhsExpr = C->getLHS())
+        if (DeclRefExpr* LHS = EvalAddr(lhsExpr))
+          return LHS;
+
+       return EvalAddr(C->getRHS());
     }
       
     // For implicit casts, we need to handle conversions from arrays to
@@ -674,10 +676,12 @@ static DeclRefExpr* EvalVal(Expr *E) {
     // non-NULL DeclRefExpr's.  If one is non-NULL, we return it.
     ConditionalOperator *C = cast<ConditionalOperator>(E);
 
-    if (DeclRefExpr *LHS = EvalVal(C->getLHS()))
-      return LHS;
-    else
-      return EvalVal(C->getRHS());
+    // Handle the GNU extension for missing LHS.
+    if (Expr *lhsExpr = C->getLHS())
+      if (DeclRefExpr *LHS = EvalVal(lhsExpr))
+        return LHS;
+
+    return EvalVal(C->getRHS());
   }
   
   // Accesses to members are potential references to data on the stack.
diff --git a/test/Analysis/conditional-op-missing-lhs.c b/test/Analysis/conditional-op-missing-lhs.c
new file mode 100644
index 0000000000..917212d387
--- /dev/null
+++ b/test/Analysis/conditional-op-missing-lhs.c
@@ -0,0 +1,26 @@
+// RUN: clang -warn-dead-stores -warn-uninit-values -verify %s
+
+void f1()
+{
+	int i;
+	
+	int j = i ? : 1; // expected-warning{{use of uninitialized variable}}
+}
+
+void *f2(int *i)
+{
+	return i ? : 0;
+}
+
+void *f3(int *i)
+{
+	int a;
+	
+	return &a ? : i;
+}
+
+void f4()
+{
+	char c[1 ? : 2];
+}
+