r363857 - [AST] Fixed extraneous warnings for binary conditional operator

[Nathan Huckleberry via cfe-commits]

Author: nathan-huckleberry
Date: Wed Jun 19 11:37:01 2019
New Revision: 363857

URL: http://llvm.org/viewvc/llvm-project?rev=363857&view=rev
Log:
[AST] Fixed extraneous warnings for binary conditional operator

Summary:
Binary conditional operator gave warnings where ternary operators
did not. They have been fixed to warn similarly to ternary operators.

Link: https://bugs.llvm.org/show_bug.cgi?id=42239

Reviewers: rsmith, aaron.ballman, nickdesaulniers

Reviewed By: rsmith, nickdesaulniers

Subscribers: srhines, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D63369

Added:
    cfe/trunk/test/Sema/warn-binary-conditional-expression-unused.c
Modified:
    cfe/trunk/lib/AST/Expr.cpp

Modified: cfe/trunk/lib/AST/Expr.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/AST/Expr.cpp?rev=363857&r1=363856&r2=363857&view=diff
==============================================================================
--- cfe/trunk/lib/AST/Expr.cpp (original)
+++ cfe/trunk/lib/AST/Expr.cpp Wed Jun 19 11:37:01 2019
@@ -2453,12 +2453,13 @@ bool Expr::isUnusedResultAWarning(const
     // If only one of the LHS or RHS is a warning, the operator might
     // be being used for control flow. Only warn if both the LHS and
     // RHS are warnings.
-    const ConditionalOperator *Exp = cast<ConditionalOperator>(this);
-    if (!Exp->getRHS()->isUnusedResultAWarning(WarnE, Loc, R1, R2, Ctx))
-      return false;
-    if (!Exp->getLHS())
-      return true;
-    return Exp->getLHS()->isUnusedResultAWarning(WarnE, Loc, R1, R2, Ctx);
+    const auto *Exp = cast<ConditionalOperator>(this);
+    return Exp->getLHS()->isUnusedResultAWarning(WarnE, Loc, R1, R2, Ctx) &&
+           Exp->getRHS()->isUnusedResultAWarning(WarnE, Loc, R1, R2, Ctx);
+  }
+  case BinaryConditionalOperatorClass: {
+    const auto *Exp = cast<BinaryConditionalOperator>(this);
+    return Exp->getFalseExpr()->isUnusedResultAWarning(WarnE, Loc, R1, R2, Ctx);
   }
 
   case MemberExprClass:

Added: cfe/trunk/test/Sema/warn-binary-conditional-expression-unused.c
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Sema/warn-binary-conditional-expression-unused.c?rev=363857&view=auto
==============================================================================
--- cfe/trunk/test/Sema/warn-binary-conditional-expression-unused.c (added)
+++ cfe/trunk/test/Sema/warn-binary-conditional-expression-unused.c Wed Jun 19 11:37:01 2019
@@ -0,0 +1,15 @@
+// RUN: %clang_cc1 -fsyntax-only -Wunused-value -verify %s
+int main() {
+    int a;
+    int b;
+    a ? : b; //expected-warning{{expression result unused}}
+    a ? a : b; //expected-warning{{expression result unused}}
+    a ? : ++b;
+    a ? a : ++b;
+    ++a ? : b; //expected-warning{{expression result unused}}
+    ++a ? a : b; //expected-warning{{expression result unused}}
+    ++a ? : ++b;
+    ++a ? a : ++b;
+    return 0;
+};
+