[cfe-commits] r165283 - in /cfe/trunk: include/clang/Basic/DiagnosticGroups.td include/clang/Basic/DiagnosticSemaKinds.td lib/Sema/SemaExpr.cpp test/Sema/parentheses.cpp

[David Blaikie]

On Thu, Oct 18, 2012 at 6:16 PM, Matt Beaumont-Gay <matthewbg at google.com> wrote:
> A little belated bikeshed-painting...
>
> On Thu, Oct 4, 2012 at 5:41 PM, David Blaikie <dblaikie at gmail.com> wrote:
>> Modified: cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td
>> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td?rev=165283&r1=165282&r2=165283&view=diff
>> ==============================================================================
>> --- cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td (original)
>> +++ cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td Thu Oct  4 19:41:03 2012
>> @@ -3863,6 +3863,11 @@
>>  def note_logical_and_in_logical_or_silence : Note<
>>    "place parentheses around the '&&' expression to silence this warning">;
>>
>> +def warn_addition_in_bitshift : Warning<
>> +  "'%0' within '%1'">, InGroup<ShiftOpParentheses>;
>
> I have a hard time understanding what problem this warning is trying
> to explain. Maybe we could phrase it like our other shift operator
> precedence warning:
> operator '?:' has lower precedence than '<<'; '<<' will be evaluated
> first [-Werror,-Wparentheses]

Fair point, improved as suggested in r166296. (pity we can't reuse the
text of a warning because it's associated with a particular flag)

I got the wording from the '||'+'&&' and '|'+'&' warning above this
one. Should we change these too?

>> +def note_addition_in_bitshift_silence : Note<
>> +  "place parentheses around the '%0' expression to silence this warning">;
>> +
>>  def warn_self_assignment : Warning<
>>    "explicitly assigning a variable of type %0 to itself">,
>>    InGroup<SelfAssignment>, DefaultIgnore;
>>
>> Modified: cfe/trunk/lib/Sema/SemaExpr.cpp
>> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaExpr.cpp?rev=165283&r1=165282&r2=165283&view=diff
>> ==============================================================================
>> --- cfe/trunk/lib/Sema/SemaExpr.cpp (original)
>> +++ cfe/trunk/lib/Sema/SemaExpr.cpp Thu Oct  4 19:41:03 2012
>> @@ -8570,6 +8570,20 @@
>>    }
>>  }
>>
>> +static void DiagnoseAdditionInShift(Sema &S, SourceLocation OpLoc,
>> +                                    Expr *SubExpr, StringRef shift) {
>> +  if (BinaryOperator *Bop = dyn_cast<BinaryOperator>(SubExpr)) {
>> +    if (Bop->getOpcode() == BO_Add || Bop->getOpcode() == BO_Sub) {
>
> Also, out of curiosity, why not warn on multiply/divide/mod?

It's just what GCC supports. We could evaluate whether
multiply/divide/mod are sufficiently error prone as to be worth
diagnosing.

- David