eduucaldas added inline comments.

================
Comment at: clang/unittests/Tooling/Syntax/TreeTest.cpp:1240
+  true;
+  false;
+}
----------------
gribozavr2 wrote:
> eduucaldas wrote:
> > gribozavr2 wrote:
> > > C99 has bool literals, but the program should include stdbool.h.
> > > 
> > > I feel like it is better to make the predicate something like 
> > > "hasBoolType()" and change the test to include stdbool.h.
> > [[ https://clang.llvm.org/doxygen/stdbool_8h_source.html | stdbool ]] 
> > consists on macro definitions, mapping booleans to integers. `true` is 
> > preprocessed into 1 and `false` to 0 .
> > I don't  think there is a reasonable way of getting the proper SyntaxTree 
> > from that macro expansion
> > 
> > Additional problem, we don't have the test infrastructure for includes, 
> > AFAIK ^^
> > 
> > Finally, regarding the predicates, I prefer if they relate to languages, 
> > otherwise we might create many predicates that test for exactly the same 
> > thing, e.g. we would have `hasBoolType()` and `hasNullPtr()` that 
> > ultimately do the same thing, test if Language is not C 
> > true is preprocessed into 1 and false to 0 .
> 
> I see -- yes, that would make a completely different syntax tree.
> 
> > Finally, regarding the predicates, I prefer if they relate to languages, 
> > otherwise we might create many predicates that test for exactly the same 
> > thing
> 
> Generally, testing for features instead of product versions is considered 
> better, as that leads to more future-proof code (for example, we learned this 
> lesson again in the area of web extensions and standards). In future, Clang 
> can start supporting a language feature in other language modes as an 
> extension (for example, supporting `_Atomic` in C++ is already a thing), or 
> the language standard itself can decide to incorporate the feature (for 
> example, C 2035 could adopt the `nullptr` keyword). It is highly unlikely for 
> complex features like templates, but may reasonably happen for simpler 
> features.
> Generally, testing for features instead of product versions is considered 
> better, as that leads to more future-proof code 

I totally agree with all you said. My worry was more regarding the fact that 
the implementation of `hasBoolType` would merely check for the language 
anyways. So if, following what you said, `true` and `false` really became a 
feature of C35 then the code would still be broken. 

But then I guess it would be easier to fix `hasBoolType` than finding all the 
places where we used just `isC` because booleans are not in C. 

Specially if all these predicates were put in `clang/Testing/CommandLineArgs.h` 
or something similar where more people would be seeing it. 

Which brings the question shouldn't we move these predicates up?


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D82310/new/

https://reviews.llvm.org/D82310



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