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/include/clang/Basic/DiagnosticGroups.td b/include/clang/Basic/DiagnosticGroups.td
index a12a4f9..a7ef218 100644
--- a/include/clang/Basic/DiagnosticGroups.td
+++ b/include/clang/Basic/DiagnosticGroups.td
@@ -122,6 +122,7 @@
def BitwiseOpParentheses: DiagGroup<"bitwise-op-parentheses">;
def LogicalOpParentheses: DiagGroup<"logical-op-parentheses">;
def ShiftOpParentheses: DiagGroup<"shift-op-parentheses">;
+def OverloadedShiftOpParentheses: DiagGroup<"overloaded-shift-op-parentheses">;
def DanglingElse: DiagGroup<"dangling-else">;
def DanglingField : DiagGroup<"dangling-field">;
def DistributedObjectModifiers : DiagGroup<"distributed-object-modifiers">;
@@ -352,6 +353,7 @@
[LogicalOpParentheses,
BitwiseOpParentheses,
ShiftOpParentheses,
+ OverloadedShiftOpParentheses,
ParenthesesOnEquality,
DanglingElse]>;
diff --git a/include/clang/Basic/DiagnosticSemaKinds.td b/include/clang/Basic/DiagnosticSemaKinds.td
index fd9ea51..1330ad6 100644
--- a/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/include/clang/Basic/DiagnosticSemaKinds.td
@@ -4041,6 +4041,13 @@
def warn_logical_and_in_logical_or : Warning<
"'&&' within '||'">, InGroup<LogicalOpParentheses>;
+def warn_overloaded_shift_in_comparison :Warning<
+ "overloaded operator %select{>>|<<}0 has lower precedence than "
+ "comparison operator">,
+ InGroup<OverloadedShiftOpParentheses>;
+def note_evaluate_comparison_first :Note<
+ "place parentheses around comparison expression to evaluate it first">;
+
def warn_addition_in_bitshift : Warning<
"operator '%0' has lower precedence than '%1'; "
"'%1' will be evaluated first">, InGroup<ShiftOpParentheses>;
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.
diff --git a/test/Sema/parentheses.cpp b/test/Sema/parentheses.cpp
index 145414a..58edc0b 100644
--- a/test/Sema/parentheses.cpp
+++ b/test/Sema/parentheses.cpp
@@ -29,6 +29,12 @@
(void)(s << b ? "foo" : "bar"); // expected-warning {{operator '?:' has lower precedence than '<<'}} \
// expected-note {{place parentheses around the '?:' expression to evaluate it first}} \
// expected-note {{place parentheses around the '<<' expression to silence this warning}}
+ (void)(s << 5 == 1); // expected-warning {{overloaded operator << has lower precedence than comparison operator}} \
+ // expected-note {{place parentheses around the '<<' expression to silence this warning}} \
+ // expected-note {{place parentheses around comparison expression to evaluate it first}}
+ (void)(s >> 5 == 1); // expected-warning {{overloaded operator >> has lower precedence than comparison operator}} \
+ // expected-note {{place parentheses around the '>>' expression to silence this warning}} \
+ // expected-note {{place parentheses around comparison expression to evaluate it first}}
}
struct S {