[PATCH] D63082: [Diagnostics] Added support for -Wint-in-bool-context

[JF Bastien via Phabricator via cfe-commits]

jfb added inline comments.


================
Comment at: test/Sema/warn-int-in-bool-context.c:26
+  r = a << 7;   // expected-warning {{'<<' in boolean context; did you mean '<'?}}
+  r = ONE << b; // expected-warning {{'<<' in boolean context; did you mean '<'?}}
+
----------------
xbolva00 wrote:
> jfb wrote:
> > xbolva00 wrote:
> > > jfb wrote:
> > > > I'm not sure the "did you mean" part is helpful. Do we have data showing that this is what people actually mean?
> > > No, no data, just what GCC suggests.
> > I would drop it without knowing that it's actually what people usually mean.
> Leave just “<<' in boolean context“ seems not ideal for me as a diag message. 
> 
> Or is it ok for you?
As [I said above](https://reviews.llvm.org/D63082#inline-585063), I don't think you should say "boolean context". It's not something people will understand. Here we're assigning to a boolean, say that.


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Comment at: test/Sema/warn-unreachable.c:147
+  // expected-warning at +1 {{'*' in boolean context, the expression will always evaluate to 'false'}}
   if (0 * x) calledFun(); // expected-warning {{will never be executed}}
 }
----------------
xbolva00 wrote:
> jfb wrote:
> > xbolva00 wrote:
> > > jfb wrote:
> > > > It seems like here the "will never be executed" warning is more useful. Do we want to emit both?
> > > Useful but -Wunreachable-code is disabled by default (not part of -Wall).
> > I don't think we want two diagnostics when one will do.
> I will drop mul handling then..
No, my feedback isn't about multiplication in particular. My feedback is that it's not useful to have both warnings. We should just emit a single warning, and it should be maximally helpful. Here it's useful to say that `calledFunc() will never be executed because 0*x is always false`.


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Comment at: test/SemaCXX/warn-int-in-bool-context.cpp:96
+
+  if (f == apple || orange) // expected-warning {{enum constant in boolean context}}
+    return a;
----------------
xbolva00 wrote:
> xbolva00 wrote:
> > @aaron.ballman : In C (but not in C++ ugh?) mode we have: 'use of logical '||' with constant operand' here..
> > 
> > /home/xbolva00/LLVM/llvm/tools/clang/test/SemaCXX/warn-int-in-bool-context.cpp:106:18: warning: use of logical '||' with constant operand
> >   if (f == apple || orange) // expected-warning {{enum constant in boolean context}}
> >                  ^  ~~~~~~
> > /home/xbolva00/LLVM/llvm/tools/clang/test/SemaCXX/warn-int-in-bool-context.cpp:106:18: note: use '|' for a bitwise operation
> >   if (f == apple || orange) // expected-warning {{enum constant in boolean context}}
> >                  ^~
> >                  |
> > /home/xbolva00/LLVM/llvm/tools/clang/test/SemaCXX/warn-int-in-bool-context.cpp:106:21: warning: enum constant in boolean context
> >   if (f == apple || orange) // expected-warning {{enum constant in boolean context}}
> > 
> > 
> > 
> > 
> What is your opinion here (^^) , @jfb ?
> 
> Thanks.
C, C++, ObjC, and ObjC++ should emit different diagnostics here. That being said, none of these diagnostics are particular easy to understand. I don't think we should ever say "boolean context" anywhere.


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D63082/new/

https://reviews.llvm.org/D63082