JonasToth added inline comments.
================
Comment at: clang-tidy/cppcoreguidelines/NarrowingConversionsCheck.cpp:34
+ hasSourceExpression(IsFloatExpr),
+ unless(hasParent(castExpr()))).bind("cast"),
+ this);
----------------
courbet wrote:
> JonasToth wrote:
> > Given C++ is weird sometimes: Is there a way that a cast might imply an
> > narrowing conversion?
> >
> > ```
> > double value = 0.4;
> > int i = static_cast<float>(value);
> > ```
> >
> > or
> >
> > ```
> > void some_function(int);
> >
> > double d = 0.42;
> > some_function(static_cast<float>(d));
> > ```
> > would come to mind.
> >
> > Nice to have, IMHO not necessary.
> Luckily that does not seem to be implicit:
>
> ```
> void f(double value) {
> int i = static_cast<float>(value);
> }
> ```
>
> ```
> FunctionDecl 0x7fe5ffbd4150
> <experimental/users/courbet/benchmark/toto.cc:1:1, line:3:1> line:1:6 f 'void
> (double)'
> |-ParmVarDecl 0x7fe5ffbd4088 <col:8, col:15> col:15 used value 'double'
> `-CompoundStmt 0x7fe5ffbd4380 <col:22, line:3:1>
> `-DeclStmt 0x7fe5ffbd4368 <line:2:3, col:36>
> `-VarDecl 0x7fe5ffbd4250 <col:3, col:35> col:7 i 'int' cinit
> `-ImplicitCastExpr 0x7fe5ffbd4350 <col:11, col:35> 'int'
> <FloatingToIntegral>
> `-CXXStaticCastExpr 0x7fe5ffbd4320 <col:11, col:35> 'float'
> static_cast<float> <NoOp>
> `-ImplicitCastExpr 0x7fe5ffbd4308 <col:30> 'float' <FloatingCast>
> `-ImplicitCastExpr 0x7fe5ffbd42f0 <col:30> 'double'
> <LValueToRValue>
> `-DeclRefExpr 0x7fe5ffbd42b0 <col:30> 'double' lvalue ParmVar
> 0x7fe5ffbd4088 'value' 'double'
> ```
>
>
>
The interesting one should get diagnosed. Could you add a test?
================
Comment at: clang-tidy/cppcoreguidelines/NarrowingConversionsCheck.cpp:41
+ binaryOperator(
+ anyOf(hasOperatorName("+="), hasOperatorName("-=")),
+ hasLHS(hasType(isInteger())),
----------------
courbet wrote:
> JonasToth wrote:
> > I would really like to add all other calc-and-assign operations. At least
> > "*=" and "/=".
> Makes sense, I've added `*=` and `/=`. All others (`%=`, `&=`, `<<=` and
> variations thereof) trigger a compilation error if the RHS is a float
> (rightfully).
>
>
For floats that is true.
If we care about the `ìnt->char` casts later, they should be added.
Repository:
rCTE Clang Tools Extra
https://reviews.llvm.org/D38455
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