[clang] [clang-tools-extra] [clang] Improved canonicalization for template specialization types (PR #135119)

[Dmitry Vasilyev via cfe-commits]

slydiman wrote:

Please note we got the assert (ASTContext.cpp, line 5619) at least on the following buildbots:

[lldb-remote-linux-win](https://lab.llvm.org/buildbot/#/builders/197):
```
UNSUPPORTED: LLDB (C:\buildbot\as-builder-10\lldb-x-aarch64\build\bin\clang.exe-aarch64) :: test_dsym (TestIteratorFromStdModule.TestCase.test_dsym)
(test case does not fall in any category of interest for this run) 
Assertion failed: Arg.structurallyEquals(getCanonicalTemplateArgument(Arg)), 
file C:\buildbot\as-builder-10\lldb-x-aarch64\llvm-project\clang\lib\AST\ASTContext.cpp, line 5619
Windows fatal exception: code 0x80000003
Current thread 0x0000287c (most recent call first):
  File "C:\buildbot\as-builder-10\lldb-x-aarch64\build\Lib\site-packages\lldb\__init__.py", line 6539 in EvaluateExpression
  File "C:\buildbot\as-builder-10\lldb-x-aarch64\llvm-project\lldb\packages\Python\lldbsuite\test\lldbtest.py", line 2547 in expect_expr
  File "C:\buildbot\as-builder-10\lldb-x-aarch64\llvm-project\lldb\test\API\commands\expression\import-std-module\iterator\TestIteratorFromStdModule.py", line 24 in test
  File "C:\buildbot\as-builder-10\lldb-x-aarch64\llvm-project\lldb\packages\Python\lldbsuite\test\decorators.py", line 148 in wrapper
  File "C:\buildbot\as-builder-10\lldb-x-aarch64\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 "C:\buildbot\as-builder-10\lldb-x-aarch64\llvm-project\lldb\packages\Python\lldbsuite\test\dotest.py", line 1108 in run_suite
  File "C:\buildbot\as-builder-10\lldb-x-aarch64\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 0x00007ffade6ec4b5 PyInit__lldb (C:\buildbot\as-builder-10\lldb-x-aarch64\build\Lib\site-packages\lldb\_lldb.cp312-win_amd64.pyd+0x9fc4b5)
  #1 0x00007ffb08a0bb04 (C:\Windows\System32\ucrtbase.dll+0x7bb04)
  #2 0x00007ffb08a0cad1 (C:\Windows\System32\ucrtbase.dll+0x7cad1)
  #3 0x00007ffb08a0e4a1 (C:\Windows\System32\ucrtbase.dll+0x7e4a1)
  #4 0x00007ffb08a0e6e1 (C:\Windows\System32\ucrtbase.dll+0x7e6e1)```
```
[lldb-remote-linux-ubuntu](https://lab.llvm.org/buildbot/#/builders/195):
```
python3.12: /home/buildbot/worker/as-builder-9/lldb-remote-linux-ubuntu/llvm-project/clang/lib/AST/ASTContext.cpp:5619:
clang::QualType clang::ASTContext::getCanonicalTemplateSpecializationType(clang::TemplateName, llvm::ArrayRef<clang::TemplateArgument>) const:
Assertion `Arg.structurallyEquals(getCanonicalTemplateArgument(Arg))' failed.
PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace.
Stack dump without symbol names (ensure you have llvm-symbolizer in your PATH or set the environment var `LLVM_SYMBOLIZER_PATH` to point to it):
0  _lldb.cpython-312-x86_64-linux-gnu.so 0x00007b63c144ae62
1  _lldb.cpython-312-x86_64-linux-gnu.so 0x00007b63c14480cf
2  _lldb.cpython-312-x86_64-linux-gnu.so 0x00007b63c1448214
3  libc.so.6                             0x00007b63c8445330
4  libc.so.6                             0x00007b63c849eb2c pthread_kill + 284
5  libc.so.6                             0x00007b63c844527e gsignal + 30
6  libc.so.6                             0x00007b63c84288ff abort + 223
7  libc.so.6                             0x00007b63c842881b
8  libc.so.6                             0x00007b63c843b517
```

https://github.com/llvm/llvm-project/pull/135119