[clang] [clang-tools-extra] [llvm] Reland: [clang] Improved canonicalization for template specialization types (PR #135414)

[Dmitry Vasilyev via cfe-commits]

slydiman wrote:

I have tested the initial commit https://github.com/llvm/llvm-project/pull/135414/commits/f8e6b60276eabe0d89db03df95af1315590b78b9

The issue is still there
```
Assertion failed: Arg.structurallyEquals(getCanonicalTemplateArgument(Arg)), file D:\as\mainline\llvm-project\clang\lib\AST\ASTContext.cpp, line 5619
 Windows fatal exception: code 0x80000003

Current thread 0x00006b58 (most recent call first):
  File "D:\test\build-lldb\Lib\site-packages\lldb\__init__.py", line 6539 in EvaluateExpression
  File "D:\test\llvm-project\lldb\packages\Python\lldbsuite\test\lldbtest.py", line 2547 in expect_expr
  File "D:\test\llvm-project\lldb\test\API\commands\expression\import-std-module\array\TestArrayFromStdModule.py", line 29 in test
  File "D:\test\llvm-project\lldb\packages\Python\lldbsuite\test\decorators.py", line 148 in wrapper
  File "D:\test\llvm-project\lldb\packages\Python\lldbsuite\test\lldbtest.py", line 1804 in test_method
  File "C:\Python312\Lib\unittest\case.py", line 589 in _callTestMethod
  File "C:\Python312\Lib\unittest\case.py", line 634 in run
  File "C:\Python312\Lib\unittest\case.py", line 690 in __call__
  File "C:\Python312\Lib\unittest\suite.py", line 122 in run
  File "C:\Python312\Lib\unittest\suite.py", line 84 in __call__
  File "C:\Python312\Lib\unittest\suite.py", line 122 in run
  File "C:\Python312\Lib\unittest\suite.py", line 84 in __call__
  File "C:\Python312\Lib\unittest\runner.py", line 240 in run
  File "D:\test\llvm-project\lldb\packages\Python\lldbsuite\test\dotest.py", line 1108 in run_suite
  File "D:\test\llvm-project\lldb\test\API\dotest.py", line 8 in <module>
PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace.
Exception Code: 0x80000003
  #0 0x00007ffd386632f5 PyInit__lldb (D:\test\build-lldb\Lib\site-packages\lldb\_lldb.cp312-win_amd64.pyd+0x9f32f5)
  #1 0x00007ffe13a71989 (C:\WINDOWS\System32\ucrtbase.dll+0xc1989)
  #2 0x00007ffe13a54ab1 (C:\WINDOWS\System32\ucrtbase.dll+0xa4ab1)
  #3 0x00007ffe13a72986 (C:\WINDOWS\System32\ucrtbase.dll+0xc2986)
  #4 0x00007ffe13a72b61 (C:\WINDOWS\System32\ucrtbase.dll+0xc2b61)
  #5 0x00007ffd3af1f959 PyInit__lldb (D:\test\build-lldb\Lib\site-packages\lldb\_lldb.cp312-win_amd64.pyd+0x32af959)
  #6 0x00007ffd3b18d481 PyInit__lldb (D:\test\build-lldb\Lib\site-packages\lldb\_lldb.cp312-win_amd64.pyd+0x351d481)
...
```
I will rebuild the debug version to get the useful stack trace.

https://github.com/llvm/llvm-project/pull/135414