r179662 - Add warning group -Woverloaded-shift-op-parentheses to -Wparentheses. This

[Richard Trieu]

Author: rtrieu
Date: Tue Apr 16 21:12:45 2013
New Revision: 179662

URL: http://llvm.org/viewvc/llvm-project?rev=179662&view=rev
Log:
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.

Modified:
    cfe/trunk/include/clang/Basic/DiagnosticGroups.td
    cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td
    cfe/trunk/lib/Sema/SemaExpr.cpp
    cfe/trunk/test/Sema/parentheses.cpp

Modified: cfe/trunk/include/clang/Basic/DiagnosticGroups.td
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Basic/DiagnosticGroups.td?rev=179662&r1=179661&r2=179662&view=diff
==============================================================================
--- cfe/trunk/include/clang/Basic/DiagnosticGroups.td (original)
+++ cfe/trunk/include/clang/Basic/DiagnosticGroups.td Tue Apr 16 21:12:45 2013
@@ -122,6 +122,7 @@ def GlobalConstructors : DiagGroup<"glob
 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 @@ def Parentheses : DiagGroup<"parentheses
                             [LogicalOpParentheses,
                              BitwiseOpParentheses,
                              ShiftOpParentheses,
+                             OverloadedShiftOpParentheses,
                              ParenthesesOnEquality,
                              DanglingElse]>;
 

Modified: cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td?rev=179662&r1=179661&r2=179662&view=diff
==============================================================================
--- cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td (original)
+++ cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td Tue Apr 16 21:12:45 2013
@@ -4041,6 +4041,13 @@ def warn_bitwise_and_in_bitwise_or : War
 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>;

Modified: cfe/trunk/lib/Sema/SemaExpr.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaExpr.cpp?rev=179662&r1=179661&r2=179662&view=diff
==============================================================================
--- cfe/trunk/lib/Sema/SemaExpr.cpp (original)
+++ cfe/trunk/lib/Sema/SemaExpr.cpp Tue Apr 16 21:12:45 2013
@@ -8877,6 +8877,33 @@ static void DiagnoseAdditionInShift(Sema
   }
 }
 
+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 @@ static void DiagnoseBinOpPrecedence(Sema
     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.

Modified: cfe/trunk/test/Sema/parentheses.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Sema/parentheses.cpp?rev=179662&r1=179661&r2=179662&view=diff
==============================================================================
--- cfe/trunk/test/Sema/parentheses.cpp (original)
+++ cfe/trunk/test/Sema/parentheses.cpp Tue Apr 16 21:12:45 2013
@@ -29,6 +29,12 @@ void f(Stream& s, bool b) {
   (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 {