Emit a slightly better warning for unused values for unary and binary operators:
t2.c:3:18: warning: expression result unused
x = ++x, ++y, y+2;
~~~~~~~~~~~~^ ~~~
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@41551 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/Sema/SemaStmt.cpp b/Sema/SemaStmt.cpp
index 6247215..300388c 100644
--- a/Sema/SemaStmt.cpp
+++ b/Sema/SemaStmt.cpp
@@ -21,6 +21,20 @@
#include "clang/Lex/IdentifierTable.h"
using namespace clang;
+/// DiagnoseDeadExpr - The specified expression is side-effect free and
+/// evaluated in a context where the result is unused. Emit a diagnostic to
+/// warn about this if appropriate.
+static void DiagnoseDeadExpr(Expr *E, Sema &S) {
+ if (const BinaryOperator *BO = dyn_cast<BinaryOperator>(E))
+ S.Diag(BO->getOperatorLoc(), diag::warn_unused_expr,
+ BO->getLHS()->getSourceRange(), BO->getRHS()->getSourceRange());
+ else if (const UnaryOperator *UO = dyn_cast<UnaryOperator>(E))
+ S.Diag(UO->getOperatorLoc(), diag::warn_unused_expr,
+ UO->getSubExpr()->getSourceRange());
+ else
+ S.Diag(E->getExprLoc(), diag::warn_unused_expr, E->getSourceRange());
+}
+
Sema::StmtResult Sema::ParseExprStmt(ExprTy *expr) {
Expr *E = static_cast<Expr*>(expr);
assert(E && "ParseExprStmt(): missing expression");
@@ -28,7 +42,7 @@
// Exprs are statements, so there is no need to do a conversion here. However,
// diagnose some potentially bad code.
if (!E->hasLocalSideEffect() && !E->getType()->isVoidType())
- Diag(E->getExprLoc(), diag::warn_unused_expr, E->getSourceRange());
+ DiagnoseDeadExpr(E, *this);
return E;
}