Wrong source range for template and templated decl

[Abramo-Bagnara]

Bugzilla Link	22472
Version	trunk
OS	Linux
CC	@DougGregor

Extended Description

For the following source:

template <int> struct C { template <typename U> struct D; };
template <int> struct D { template <typename U> void f(); };

template <> template <typename V> struct C<0>::D { };
template <> template <typename V> void D<0>::f();

the AST generated for last two lines is:

|-ClassTemplateDecl 0x8036740 parent 0x8030360 prev 0x80306f0 <line:4:13, col:52> col:48 D
| |-TemplateTypeParmDecl 0x8030290 <col:23, col:32> col:32 typename V
| `-CXXRecordDecl 0x8036670 parent 0x8030360 prev 0x8030660 <col:1, col:52> col:48 struct D definition
|   `-CXXRecordDecl 0x8036810 <col:35, col:48> col:48 implicit struct D
`-FunctionTemplateDecl 0x8036ee0 parent 0x8036950 prev 0x8036cf0 <line:5:13, col:48> col:46 f
  |-TemplateTypeParmDecl 0x80368b0 <col:23, col:32> col:32 typename V
  `-CXXMethodDecl 0x8036df0 parent 0x8036950 prev 0x8036c50 <col:1, col:48> col:46 f 'void (void)'

As it can be observed the templated decls (CXXRecordDecl and CXXMethodDecl) have a range that is larger than the related template decl (ClassTemplateDecl and FunctionTemplateDecl).

This breaks the invariant that asks that inner nodes have a range that is a subset or equal to range of outer nodes.

A sensible approach would be that templated CXXRecordDecl and DeclaratorDecl have the begin of their source range at current InnerLocStart and that the ClassTemplateDecl/FunctionTemplateDecl have the begin of their source range in the location of the outer template keyword.

[Endilll]

Still there in Clang 21.0: https://godbolt.org/z/YY15qfaEj

[llvmbot]

@llvm/issue-subscribers-clang-frontend

Author: None (Abramo-Bagnara)

| | | | --- | --- | | Bugzilla Link | [22472](https://llvm.org/bz22472) | | Version | trunk | | OS | Linux | | CC | @DougGregor |

Extended Description

For the following source:

template <int> struct C { template <typename U> struct D; };
template <int> struct D { template <typename U> void f(); };

template <> template <typename V> struct C<0>::D { };
template <> template <typename V> void D<0>::f();

the AST generated for last two lines is:

|-ClassTemplateDecl 0x8036740 parent 0x8030360 prev 0x80306f0 <line:4:13, col:52> col:48 D
| |-TemplateTypeParmDecl 0x8030290 <col:23, col:32> col:32 typename V
| `-CXXRecordDecl 0x8036670 parent 0x8030360 prev 0x8030660 <col:1, col:52> col:48 struct D definition
|   `-CXXRecordDecl 0x8036810 <col:35, col:48> col:48 implicit struct D
`-FunctionTemplateDecl 0x8036ee0 parent 0x8036950 prev 0x8036cf0 <line:5:13, col:48> col:46 f
  |-TemplateTypeParmDecl 0x80368b0 <col:23, col:32> col:32 typename V
  `-CXXMethodDecl 0x8036df0 parent 0x8036950 prev 0x8036c50 <col:1, col:48> col:46 f 'void (void)'

As it can be observed the templated decls (CXXRecordDecl and CXXMethodDecl) have a range that is larger than the related template decl (ClassTemplateDecl and FunctionTemplateDecl).

This breaks the invariant that asks that inner nodes have a range that is a subset or equal to range of outer nodes.

A sensible approach would be that templated CXXRecordDecl and DeclaratorDecl have the begin of their source range at current InnerLocStart and that the ClassTemplateDecl/FunctionTemplateDecl have the begin of their source range in the location of the outer template keyword.