Implement a warning for mixing bitwise logical with comparison ops. Fixes PR5297.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@85117 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Sema/SemaExpr.cpp b/lib/Sema/SemaExpr.cpp
index 78647e3..84a430a 100644
--- a/lib/Sema/SemaExpr.cpp
+++ b/lib/Sema/SemaExpr.cpp
@@ -5412,6 +5412,53 @@
OpLoc));
}
+static inline bool IsBitwise(int Opc) {
+ return Opc >= BinaryOperator::And && Opc <= BinaryOperator::Or;
+}
+static inline bool IsEqOrRel(int Opc) {
+ return Opc >= BinaryOperator::LT && Opc <= BinaryOperator::NE;
+}
+
+static void DiagnoseBitwisePrecedence(Sema &Self, BinaryOperator::Opcode Opc,
+ SourceLocation OpLoc,Expr *lhs,Expr *rhs){
+ typedef BinaryOperator::Opcode Opcode;
+ int lhsopc = -1, rhsopc = -1;
+ if (BinaryOperator *BO = dyn_cast<BinaryOperator>(lhs))
+ lhsopc = BO->getOpcode();
+ if (BinaryOperator *BO = dyn_cast<BinaryOperator>(rhs))
+ rhsopc = BO->getOpcode();
+
+ // Subs are not binary operators.
+ if (lhsopc == -1 && rhsopc == -1)
+ return;
+
+ // Bitwise operations are sometimes used as eager logical ops.
+ // Don't diagnose this.
+ if ((IsEqOrRel(lhsopc) || IsBitwise(lhsopc)) &&
+ (IsEqOrRel(rhsopc) || IsBitwise(rhsopc)))
+ return;
+
+ if (IsEqOrRel(lhsopc))
+ Self.Diag(OpLoc, diag::warn_precedence_bitwise_rel)
+ << SourceRange(lhs->getLocStart(), OpLoc)
+ << BinaryOperator::getOpcodeStr(Opc)
+ << BinaryOperator::getOpcodeStr(static_cast<Opcode>(lhsopc));
+ else if (IsEqOrRel(rhsopc))
+ Self.Diag(OpLoc, diag::warn_precedence_bitwise_rel)
+ << SourceRange(OpLoc, rhs->getLocEnd())
+ << BinaryOperator::getOpcodeStr(Opc)
+ << BinaryOperator::getOpcodeStr(static_cast<Opcode>(rhsopc));
+}
+
+/// DiagnoseBinOpPrecedence - Emit warnings for expressions with tricky
+/// precedence. This currently diagnoses only "arg1 'bitwise' arg2 'eq' arg3".
+/// But it could also warn about arg1 && arg2 || arg3, as GCC 4.3+ does.
+static void DiagnoseBinOpPrecedence(Sema &Self, BinaryOperator::Opcode Opc,
+ SourceLocation OpLoc, Expr *lhs, Expr *rhs){
+ if (IsBitwise(Opc))
+ DiagnoseBitwisePrecedence(Self, Opc, OpLoc, lhs, rhs);
+}
+
// Binary Operators. 'Tok' is the token for the operator.
Action::OwningExprResult Sema::ActOnBinOp(Scope *S, SourceLocation TokLoc,
tok::TokenKind Kind,
@@ -5422,6 +5469,9 @@
assert((lhs != 0) && "ActOnBinOp(): missing left expression");
assert((rhs != 0) && "ActOnBinOp(): missing right expression");
+ // Emit warnings for tricky precedence issues, e.g. "bitfield & 0x4 == 0"
+ DiagnoseBinOpPrecedence(*this, Opc, TokLoc, lhs, rhs);
+
if (getLangOptions().CPlusPlus &&
(lhs->getType()->isOverloadableType() ||
rhs->getType()->isOverloadableType())) {