[PATCH] D113859: [Sema] Fix consteval function calls with value-dependent args

[Léo Lam via Phabricator via cfe-commits]

leoetlino added a comment.

While this patch doesn't introduce new regressions and does fix compilation of the code snippet mentioned earlier, I'm not sure this is the correct approach, considering there are a bunch of other similar template-related consteval bugs that this patch does *not* fix:

  template <typename T>
  struct Foo {
      static consteval void ok(int) {}
  
      static consteval void bad(T) {}
  
      template <typename U>
      static consteval void call(T x, U fn) { fn(x); }
  
      static constexpr bool test() {
          ok({});
          bad({});  // error: cannot take address of consteval function 'bad' outside of an immediate invocation
          call({}, bad);  // error: cannot take address of consteval function 'bad' outside of an immediate invocation
          return true;
      }
  };

The problem seems to be that the call/arguments are type dependent so nothing is added to `ImmediateInvocationCandidates` -- and so `HandleImmediateInvocations` (in SemaExpr.cpp) never removes anything from `ReferenceToConsteval` despite the references to the consteval functions being used for immediate invocations.

Another variant of the issue:

  template <typename T>
  struct Bar {
      static consteval void bad(int) {}
  
      static constexpr bool test() {
          bad(T::value);  // error: cannot take address of consteval function 'bad' outside of an immediate invocation
          return true;
      }
  };

Not sure what the best way of fixing those issues would be -- any guidance would be greatly appreciated!


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D113859/new/

https://reviews.llvm.org/D113859