Add warning group -Woverloaded-shift-op-parentheses to -Wparentheses. This
will fire on code such as:
cout << x == 0;
which the compiler will intrepret as
(cout << x) == 0;
This warning comes with two fixits attached to notes, one for parentheses to
silence the warning, and another to evaluate the comparison first.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@179662 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Sema/SemaExpr.cpp b/lib/Sema/SemaExpr.cpp
index cdfdc09..ce60f91 100644
--- a/lib/Sema/SemaExpr.cpp
+++ b/lib/Sema/SemaExpr.cpp
@@ -8877,6 +8877,33 @@
}
}
+static void DiagnoseShiftCompare(Sema &S, SourceLocation OpLoc,
+ Expr *LHSExpr, Expr *RHSExpr) {
+ CXXOperatorCallExpr *OCE = dyn_cast<CXXOperatorCallExpr>(LHSExpr);
+ if (!OCE)
+ return;
+
+ FunctionDecl *FD = OCE->getDirectCallee();
+ if (!FD || !FD->isOverloadedOperator())
+ return;
+
+ OverloadedOperatorKind Kind = FD->getOverloadedOperator();
+ if (Kind != OO_LessLess && Kind != OO_GreaterGreater)
+ return;
+
+ S.Diag(OpLoc, diag::warn_overloaded_shift_in_comparison)
+ << LHSExpr->getSourceRange() << RHSExpr->getSourceRange()
+ << (Kind == OO_LessLess);
+ SuggestParentheses(S, OpLoc,
+ S.PDiag(diag::note_evaluate_comparison_first),
+ SourceRange(OCE->getArg(1)->getLocStart(),
+ RHSExpr->getLocEnd()));
+ SuggestParentheses(S, OCE->getOperatorLoc(),
+ S.PDiag(diag::note_precedence_silence)
+ << (Kind == OO_LessLess ? "<<" : ">>"),
+ OCE->getSourceRange());
+}
+
/// DiagnoseBinOpPrecedence - Emit warnings for expressions with tricky
/// precedence.
static void DiagnoseBinOpPrecedence(Sema &Self, BinaryOperatorKind Opc,
@@ -8905,6 +8932,11 @@
DiagnoseAdditionInShift(Self, OpLoc, LHSExpr, Shift);
DiagnoseAdditionInShift(Self, OpLoc, RHSExpr, Shift);
}
+
+ // Warn on overloaded shift operators and comparisons, such as:
+ // cout << 5 == 4;
+ if (BinaryOperator::isComparisonOp(Opc))
+ DiagnoseShiftCompare(Self, OpLoc, LHSExpr, RHSExpr);
}
// Binary Operators. 'Tok' is the token for the operator.