[PATCH] D77809: [Analyzer] Include typedef statements in CFG build.

[Balázs Kéri via Phabricator via cfe-commits]

balazske added inline comments.


================
Comment at: clang/test/Analysis/cfg.cpp:570
 }
 
+// CHECK-LABEL: void vla_simple(int x)
----------------
aaron.ballman wrote:
> NoQ wrote:
> > balazske wrote:
> > > balazske wrote:
> > > > aaron.ballman wrote:
> > > > > Can you also add tests for:
> > > > > ```
> > > > > int vla_unevaluated(int x) {
> > > > >   // Evaluates the ++x
> > > > >   sizeof(int[++x]);
> > > > >   // Does not evaluate the ++x
> > > > >   _Alignof(int[++x]);
> > > > >   _Generic((int(*)[++x])0, default : 0);
> > > > >   
> > > > >   return x;
> > > > > }
> > > > > ```
> > > > > 
> > > > > Also, it's a bit strange to find these VLA tests in a .cpp file. VLAs are a C++ extension and we should have some testing for them for constructs that are C++-specific, but I would have expected many of these tests to be in a C file instead.
> > > > Could be there platforms (on buildbot?) where the VLA code (in cpp file) does not compile? Is it worth to have a test with VLA type alias then?
> > > I have this output for the test above (without the new code), is it correct?
> > > (The `++` seems to be evaluated for the `alignof` statement too.)
> > > ```
> > > int vla_unevaluated(int x)
> > >  [B2 (ENTRY)]
> > >    Succs (1): B1
> > > 
> > >  [B1]
> > >    1: x
> > >    2: ++[B1.1]
> > >    3: [B1.2] (ImplicitCastExpr, LValueToRValue, int)
> > >    4: sizeof(int [++x])
> > >    5: x
> > >    6: ++[B1.5]
> > >    7: [B1.6] (ImplicitCastExpr, LValueToRValue, int)
> > >    8: alignof(int [++x])
> > >    9: 0
> > >   10: x
> > >   11: [B1.10] (ImplicitCastExpr, LValueToRValue, int)
> > >   12: return [B1.11];
> > >    Preds (1): B2
> > >    Succs (1): B0
> > > 
> > >  [B0 (EXIT)]
> > >    Preds (1): B1
> > > 
> > > ```
> > > Could be there platforms (on buildbot?) where the VLA code (in cpp file) does not compile? Is it worth to have a test with VLA type alias then?
> > 
> > That's unlikely; the problems with VLAs in C++ are IIRC about the bureaucracy of the Standard (i.e., they couldn't solve enough cornercases, like whether `T<int[x]>` and `T<int[y]>` the same template when `x == y` at run-time?), not about platform support.
> > Could be there platforms (on buildbot?) where the VLA code (in cpp file) does not compile? Is it worth to have a test with VLA type alias then?
> 
> I think the type alias test is a good idea (as are any other C++-specific tests) because we support VLAs in C++ mode as an extension, my concern was more that this is a C feature and so if I was hunting for tests for VLAs, I'd look  in a .c file first. It's not a huge concern, more like a style nit.
> 
> > (The ++ seems to be evaluated for the alignof statement too.)
> 
> That seems wrong per C17 6.5.3.4p3. It also doesn't seem to match the behavior I'm seeing: https://godbolt.org/z/rVaGnb
> 
There is a //cfg.cpp// test file but not a //cfg.c// so the new tests are added to the cpp file. I do not like to make a new //cfg.c// because it will contain a part of the VLA tests only because the type alias cases. It is better to have all VLA tests in the same file.

The case in `vla_unevaluated` is probably wrong but an independent problem. This change would be only about adding the VLA related parts.


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https://reviews.llvm.org/D77809