hokein added a comment.
In D85282#2198737 <https://reviews.llvm.org/D85282#2198737>, @nridge wrote:
> This patch has helped me understand the difference between the two
> `ConceptReference`s in the AST (the `TypeConstraint` and the
> `ConceptSpecializationExpr`).
>
> Given that
>
> `template <binary_concept<int> R>`
>
> is a shorthand for
>
> `template <typename R> requires binary_concept<R, int>`
>
> the `TypeConstraint` is the explicitly written `binary_concept<int>` whose
> `getTemplateArgsAsWritten()` has one element: `<int>`.
>
> Meanwhile the `ConceptSpecializationExpr` is the implicit `binary_concept<R,
> int>` whose `getTemplateArgsAsWritten()` has two elements: `<R, int>`.
Yes, true.
> Is there a reason to prefer dumping one over the other (or even both)?
This is a good question. Currently we don't dump `TypeConstrain` instead we
dump the responding immediately declared constraint (which is a
`ConceptSpecializationExpr`).
I think it is ok to just dump the immediately declared constraint as
TypeConstrain is just a wrapper of it.
template <binary_concept<int> R>
before this patch:
TemplateTypeParmDecl R
|- ConceptSpecializationExpr
`- TemplateArgument {{.*}} type 'int'
after this patch:
TemplateTypeParmDecl R
|- ConceptSpecializationExpr
|- TemplateArgument {{.*}} type 'R'
`- TemplateArgument {{.*}} type 'int'
maybe the following is better:
TemplateTypeParmDecl R
|- TypeContraint
`- ConceptSpecializationExpr
|- TemplateArgument {{.*}} type 'R'
`- TemplateArgument {{.*}} type 'int'
The behavior (before this patch) is to dump the written template arguments in
`TypeConstraint` as part of the `TemplateTypeParmDecl`, which doesn't seem to
reasonable.
It also confuses the default template argument case.
template<typename T = int>
// is dump as
TemplateTypeParmDecl T
`-TemplateArgument type 'int'
================
Comment at: clang/test/AST/ast-dump-concepts.cpp:18
// CHECK: TemplateTypeParmDecl {{.*}} referenced Concept {{.*}}
'binary_concept'
- // CHECK-NEXT: |-ConceptSpecializationExpr {{.*}} <col:13, col:31> 'bool'
Concept {{.*}} 'binary_concept'
- // CHECK-NEXT: `-TemplateArgument {{.*}} type 'int'
----------------
nridge wrote:
> The ending column number here was important (it tested the fix to
> `ConceptSpecializationExpr::getEndLoc()` in D86413).
oh, I lost it during the rebase, added it back.
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D85282/new/
https://reviews.llvm.org/D85282
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