cor3ntin added inline comments.
================
Comment at: clang/lib/Sema/SemaDeclCXX.cpp:16824-16841
if (InnerCond && isa<ConceptSpecializationExpr>(InnerCond)) {
// Drill down into concept specialization expressions to see why they
// weren't satisfied.
Diag(StaticAssertLoc, diag::err_static_assert_failed)
<< !AssertMessage << Msg.str() << AssertExpr->getSourceRange();
ConstraintSatisfaction Satisfaction;
if (!CheckConstraintSatisfaction(InnerCond, Satisfaction))
----------------
aaron.ballman wrote:
> cor3ntin wrote:
> > rsmith wrote:
> > > I wonder if it's worth adding a custom diagnostic (eg, "this template
> > > cannot be instantiated: %0") for the case where we're in template
> > > instantiation and the expression is the bool literal `false`.
> > I'm not sure i see the motivation. Why would we want to special case
> > `false`? The expression could also be an always false, never dependent
> > expression
> Richard may have different ideas in mind, but the motivation to me is code
> like:
> ```
> template <typename Ty>
> struct S {
> static_assert(false, "you have to use one of the valid specializations, not
> the primary template");
> };
>
> template <>
> struct S<int> {
> };
>
> template <>
> struct S<float> {
> };
>
> int main() {
> S<int> s1;
> S<float> s2;
> S<double> s3;
> }
> ```
> Rather than telling the user the static_assert failed because false is not
> true, having a custom diagnostic might read better for users. GCC doesn't
> produce a custom diagnostic -- the behavior isn't terrible, but the "false
> evaluates to false" note is effectively just noise, too:
> https://godbolt.org/z/456bzWG7c
OH. That makes sense now, thanks. I think I agree.
Interestingly, in gcc immediate calls are really immediate :)
https://godbolt.org/z/b3vrzf4sj
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D144285/new/
https://reviews.llvm.org/D144285
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