Reland of #78387
Use the template pattern in determining whether to synthesize the
aggregate deduction guide, and update
DeclareImplicitDeductionGuideFromInitList to substitute outer template
arguments.
The tests in the original patch made an assumption about the size of a
pointer type, and this led to them failing on targets with 32-bit
pointers. The tests have been updated to not depend on the size of any
type. This only requires updates to the test file, no functionality has
otherwise changed between this and the original patch.
Use the template pattern in determining whether to synthesize the
aggregate deduction guide, and update
DeclareImplicitDeductionGuideFromInitList to substitute outer template
arguments.
Fixes#77599
Reland of f418319730341e9d41ce8ead6fbfe5603c343985 with proper handling
of template constructors
When a nested template is instantiated, the template pattern of the
inner class is not copied into the outer class
ClassTemplateSpecializationDecl. The specialization contains a
ClassTemplateDecl with an empty record that points to the original
template pattern instead.
As a result, when looking up the constructors of the inner class, no
results are returned. This patch finds the original template pattern and
uses that for the lookup instead.
Based on CWG2471 we must also substitute the known outer template
arguments when creating deduction guides for the inner class.
Changes from last iteration:
1. In template constructors, arguments are first rewritten to depth - 1
relative to the constructor as compared to depth 0 originally. These
arguments are needed for substitution into constraint expressions.
2. Outer arguments are then applied with the template instantiator to
produce a template argument at depth zero for use in the deduction
guide. This substitution does not evaluate constraints, which preserves
constraint arguments at the correct depth for later evaluation.
3. Tests are added that cover template constructors within nested
deduction guides for all special substitution cases.
4. Computation of the template pattern and outer instantiation arguments
are pulled into the constructor of
`ConvertConstructorToDeductionGuideTransform`.
Reland of dd0fba11690f9fef304d5f48cde646e5eca8d3c0
When a nested template is instantiated, the template pattern of the
inner class is not copied into the outer class
ClassTemplateSpecializationDecl. The specialization contains a
ClassTemplateDecl with an empty record that points to the original
template pattern instead.
As a result, when looking up the constructors of the inner class, no
results are returned. This patch finds the original template pattern and
uses that for the lookup instead.
Based on CWG2471 we must also substitute the known outer template
arguments when creating deduction guides for the inner class.
Changes from the last iteration:
1. The outer retained levels from the outer template are always added to
the `MultiLevelTemplateArgumentList` for rewriting
`FunctionTemplateDecl` arguments, even if there is no FTD and the
arguments are empty.
2. When building implicit deduction guides, the template pattern
underlying decl is pushed as the current context. This resolves the
issue where `FindInstantiatedDecl` is unable to find the inner template
class.
3. Tests are updated to cover the failing case, and to assert that the
type is correct after argument deduction in the implicit case.
This reverts commit dd0fba11690f9fef304d5f48cde646e5eca8d3c0.
It fails on nested classes that have both an explicit deduction guide and
a constructor that has an argument of the same type as the class (i.e. a copy constructor).
When a nested template is instantiated, the template pattern of the
inner class is not copied into the outer class
ClassTemplateSpecializationDecl. The specialization contains a
ClassTemplateDecl with an empty record that points to the original
template pattern instead.
As a result, when looking up the constructors of the inner class, no
results are returned. This patch finds the original template pattern and
uses that for the lookup instead.
Based on CWG2471 we must also substitute the known outer template
arguments when creating deduction guides for the inner class.
Fixes#46200Fixes#57812
