[PATCH] D155270: [clang][Interp] Basic support for bit fields

[Aaron Ballman via Phabricator via cfe-commits]

aaron.ballman added a comment.

Precommit CI is currently crashing on the newly introduced test case.



================
Comment at: clang/test/AST/Interp/bitfields.cpp:36
+  // TODO: +=, -=, etc. operators.
+}
----------------
shafik wrote:
> This is an interesting test case:
> 
> ```
> struct A {int c:3;};
> 
> constexpr int f() {
>   A a1{3};
>   return a1.c++;
> }
> 
> void g() {
>     constexpr int x = f();
> }
> ```
> 
> We are overflowing the bit-field value but it is implementation defined what the value is 😱 CC @aaron.ballman 
> 
> Might be worth checking the result of conditional operator and comma etc are bit-fields when they are supposed to be and therefore sizeof fails for those cases. 
Yeah, the bit-field overflow case is http://eel.is/c++draft/expr.ass#4 -- we don't document what we do in this case (so this is a good opportunity to improve our docs), but we appear to treat it the same as overflow for a non-bit-field integer type: https://godbolt.org/z/4Ta7KoP58


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  https://reviews.llvm.org/D155270/new/

https://reviews.llvm.org/D155270