clang-format ignores un-ignored paths in .clang-format-ignore with same prefix

[tdscheper]

Environment

• OS and Version: macOS Sequoia 15.5
• VS Code Version: 1.101.0-insider
• C/C++ Extension Version: 1.3.1

Bug Summary and Steps to Reproduce

Given the following folder structure:

.
├── .clang-format
├── .clang-format-ignore
├── .vscode
│   ├── c_cpp_properties.json
│   └── settings.json
├── foo
│   └── foo.h
└── foo_tests
    └── test_foo.c

And this .clang-format-ignore:

*
!foo/*
!foo_tests/*

Formatting foo/foo.h and foo_tests/test_foo.h via the extension does nothing.

When .clang-format-ignore is instead:

*
!foo/*

Formatting foo/foo.h formats as expected, and foo_tests/test_foo.h does not get formatted, also as expected.

When !foo/* is not there and !foo_tests/* is there, expected behavior occurs also.

With the full .clang-format-ignore and running the clang-format packaged in the extension like this:

~/.vscode-insiders/extensions/ms-vscode.cpptools-1.25.3-darwin-arm64/LLVM/bin/clang-format --style=file -i foo/foo.h

foo/foo.h gets formatted as expected. So, I'd expect this to be an issue with the extension, not clang-format.

Configuration and Logs

-------- Diagnostics - 6/12/2025, 10:25:54 PM
Version: 1.25.3
Current Configuration:
{
    "name": "Mac",
    "includePath": [
        "/Users/tdscheper/dev/repo/sandboxes/C/foo"
    ],
    "defines": [],
    "cStandard": "c17",
    "cppStandard": "c++14",
    "intelliSenseMode": "macos-clang-arm64",
    "compilerPath": "/usr/bin/gcc",
    "compilerPathIsExplicit": true,
    "cStandardIsExplicit": true,
    "cppStandardIsExplicit": true,
    "intelliSenseModeIsExplicit": true,
    "recursiveIncludesReduceIsExplicit": false,
    "recursiveIncludesPriorityIsExplicit": false,
    "recursiveIncludesOrderIsExplicit": false,
    "compilerPathInCppPropertiesJson": "/usr/bin/gcc",
    "mergeConfigurations": false,
    "recursiveIncludes": {},
    "browse": {
        "limitSymbolsToIncludedHeaders": true
    }
}
Modified Settings:
{
    "C_Cpp.default.compilerPath": "/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang"
}
Additional Tracked Settings:
{
    "editorTabSize": 4,
    "editorInsertSpaces": true,
    "editorAutoClosingBrackets": "languageDefined",
    "filesEncoding": "utf8",
    "filesAssociations": {
        ".arxml": "xml",
        ".clang-format": "yaml",
        ".clang-format-ignore": "ignore"
    },
    "filesExclude": {
        "**/.git": true,
        "**/.svn": true,
        "**/.hg": true,
        "**/.DS_Store": true,
        "**/Thumbs.db": true,
        "**/__pycache__": true,
        "**/.ruff_cache": true,
        "**/.mypy_cache": true,
        "**/.pytest_cache": true
    },
    "filesAutoSaveAfterDelay": false,
    "editorInlayHintsEnabled": true,
    "editorParameterHintsEnabled": true,
    "searchExclude": {
        "**/node_modules": true,
        "**/bower_components": true,
        "**/*.code-search": true
    },
    "workbenchSettingsEditor": "ui"
}
cpptools version (native): 1.25.3.0
Current database path: /Users/tdscheper/Library/Caches/vscode-cpptools/e82bc75c15d3363dec518c71b74031cf/.browse.VC.db
Translation Unit Mappings:
[ /Users/tdscheper/dev/repo/sandboxes/C/foo_tests/test_foo.c - source TU]:
    /Users/tdscheper/dev/repo/sandboxes/C/foo/foo.h
Translation Unit Configurations:
[ /Users/tdscheper/dev/repo/sandboxes/C/foo_tests/test_foo.c ]
    Process ID: 6458
    Memory Usage: 32 MB
    Compiler Path: /usr/bin/gcc
    Include paths:
        include: /Users/tdscheper/dev/repo/sandboxes/C/foo
        system include: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib/clang/17/include
        system include: /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/include
        system include: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include
        system framework search path (default): /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/System/Library/Frameworks
    Standard Version: c17
    IntelliSense Mode: macos-clang-arm64
    Other Flags:
        --clang
        --clang_version=170006
Total Memory Usage: 32 MB

------- Workspace parsing diagnostics -------
Number of files discovered (not excluded): 9836
Number of files parsed: 232

Other Extensions

No response

Additional context

No response