[PATCH] D146178: [Clang][Sema] Fix comparison of constraint expressions

[Alexander Shaposhnikov via Phabricator via cfe-commits]

alexander-shaposhnikov added inline comments.


================
Comment at: clang/lib/Sema/SemaTemplateInstantiate.cpp:133
 }
 
+Response HandlePartialClassTemplateSpec(
----------------
alexander-shaposhnikov wrote:
> alexander-shaposhnikov wrote:
> > alexander-shaposhnikov wrote:
> > > HandlePartialClassTemplateSpec is from Erich's diff 
> > > (https://reviews.llvm.org/D147722)
> > @erichkeane : previously (see https://reviews.llvm.org/D147722) we were 
> > producing a real layer of arguments (if the depth is greater than 1), to 
> > the best of my knowledge this is incorrect since it'd trigger unexpected 
> > depth adjustment, we should produce retained layers instead.
> (depth adjustment during the substitution)
to make it a bit easier to reason about I've changed the names in the test case:

```
//enum class Enum { E1 };

template <typename T1>
concept some_concept = true;
//inline constexpr bool some_concept = true;

template <typename T1, int>
struct S {
  template <typename T2>
  requires(some_concept<T2>)
  void func(const T2 &);
};

template <typename T11>
struct S<T11, 0> {
  template <typename T22>
  requires(some_concept<T22>)
  void func(const T22 &);
};

template <typename T111>
template <typename T222>
requires (some_concept<T222>)
inline void S<T111, 0>::func(const T222 &) {}
```

Previously the code was doing the following:
```
PartialClassTemplSpec->getTemplateDepth() = 1
NumRetainedOuterLevels: 0
0: <>
before subst:
ParenExpr 0x558fb90be6a8 '_Bool'
`-ConceptSpecializationExpr 0x558fb90be640 '_Bool' Concept 0x558fb909fbd8 
'some_concept'
  |-ImplicitConceptSpecializationDecl 0x558fb90be5d0 
  | `-TemplateArgument type 'type-parameter-1-0'
  |   `-TemplateTypeParmType 0x558fb90a01d0 'type-parameter-1-0' dependent 
depth 1 index 0
  `-TemplateArgument type 'T22'
    `-TemplateTypeParmType 0x558fb90be590 'T22' dependent depth 1 index 0
      `-TemplateTypeParm 0x558fb90be540 'T22'
after subst:
ParenExpr 0x558fb90bf168 '_Bool'
`-ConceptSpecializationExpr 0x558fb90bf100 '_Bool' Concept 0x558fb909fbd8 
'some_concept'
  |-ImplicitConceptSpecializationDecl 0x558fb90bf090 
  | `-TemplateArgument type 'type-parameter-0-0'
  |   `-TemplateTypeParmType 0x558fb909fb50 'type-parameter-0-0' dependent 
depth 0 index 0
  `-TemplateArgument type 'T22'
    `-TemplateTypeParmType 0x558fb90bf050 'T22' dependent depth 0 index 0
      `-TemplateTypeParm 0x558fb90be540 'T22'
```
(as one can see the depths have changed)

now:
```
PartialClassTemplSpec->getTemplateDepth() = 1
NumRetainedOuterLevels: 1
before subst:
ParenExpr 0x55f7813ae6a8 '_Bool'
`-ConceptSpecializationExpr 0x55f7813ae640 '_Bool' Concept 0x55f78138fbd8 
'some_concept'
  |-ImplicitConceptSpecializationDecl 0x55f7813ae5d0 
  | `-TemplateArgument type 'type-parameter-1-0'
  |   `-TemplateTypeParmType 0x55f7813901d0 'type-parameter-1-0' dependent 
depth 1 index 0
  `-TemplateArgument type 'T22'
    `-TemplateTypeParmType 0x55f7813ae590 'T22' dependent depth 1 index 0
      `-TemplateTypeParm 0x55f7813ae540 'T22'
after subst:
ParenExpr 0x55f7813af138 '_Bool'
`-ConceptSpecializationExpr 0x55f7813af0d0 '_Bool' Concept 0x55f78138fbd8 
'some_concept'
  |-ImplicitConceptSpecializationDecl 0x55f7813af060 
  | `-TemplateArgument type 'type-parameter-1-0'
  |   `-TemplateTypeParmType 0x55f7813901d0 'type-parameter-1-0' dependent 
depth 1 index 0
  `-TemplateArgument type 'T22'
    `-TemplateTypeParmType 0x55f7813ae590 'T22' dependent depth 1 index 0
      `-TemplateTypeParm 0x55f7813ae540 'T22'
```




Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D146178/new/

https://reviews.llvm.org/D146178

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