Incorrect Colorization for Custom Iterator Type

Bug type: Language Service

Describe the bug

• OS and Version: MacOS Big Sur 11.4
• VS Code Version: 1.66.0
• C/C++ Extension Version: 1.9.7
• Other extensions you installed (and if the issue persists after disabling them): None

Workspace is a single C++ file containing a definition of a custom std::forward_iterator_tag implementation. Colorization of this is incorrect when used in a for loop as in below picture:

Steps to reproduce
Open MWE with setting "C_Cpp.enhancedColorization": "Enabled".

Expected behavior
Brackets are colorized as normal.

Code sample and logs

• Code sample

#include <iostream>

class Foo {
    public:
        int a;
        
        Foo(int a) : a( a ) {}
};

class FooIterator : public std::forward_iterator_tag {
    public:
        int a;
        const Foo* f;
        
        FooIterator(int a, const Foo& f) : a( a ), f( &f ) {}
        
        FooIterator operator++() {
            advance();
            return *this;
        }
        
        bool operator==(const FooIterator& f) const {
            return this->a == f.a;
        }
        
        bool operator!=(const FooIterator& f) const {
            return this->a != f.a;
        }

        int operator*() const {
            return a;
        }
        
        void advance() {
            a++;
        }
};

FooIterator begin(const Foo& f) {
    return FooIterator(0, f);
}

FooIterator end(const Foo& f) {
    return FooIterator(f.a, f);
}

int main() {
    Foo f(10);
    
    for (int a : f) {
        std::cout << a << std::endl;
    }
    
    return 0;
}

• Configurations in c_cpp_properties.json

{
    "configurations": [
        {
            "name": "Mac",
            "includePath": [
                "${workspaceFolder}/**"
            ],
            "defines": [],
            "macFrameworkPath": [
                "/Library/Developer/CommandLineTools/SDKs/MacOSX11.sdk/System/Library/Frameworks"
            ],
            "compilerPath": "/usr/bin/g++",
            "cStandard": "c17",
            "cppStandard": "c++20"
        }
    ],
    "version": 4
}

• Logs from running C/C++: Log Diagnostics from the VS Code command palette

-------- Diagnostics - 3/31/2022, 3:25:00 PM
Version: 1.9.7
Current Configuration:
{
    "name": "Mac",
    "includePath": [
        "${workspaceFolder}/**"
    ],
    "defines": [],
    "macFrameworkPath": [
        "/Library/Developer/CommandLineTools/SDKs/MacOSX11.sdk/System/Library/Frameworks"
    ],
    "compilerPath": "/usr/bin/g++",
    "cStandard": "c17",
    "cppStandard": "c++20",
    "compilerPathIsExplicit": true,
    "cStandardIsExplicit": true,
    "cppStandardIsExplicit": true,
    "intelliSenseModeIsExplicit": false,
    "compilerArgs": [],
    "mergeConfigurations": false,
    "browse": {
        "path": [
            "${workspaceFolder}/**"
        ],
        "limitSymbolsToIncludedHeaders": true
    }
}
Translation Unit Mappings:
[ /Users/Lars/Desktop/ColoringIssue/main.cpp ]:
    /Users/Lars/Desktop/ColoringIssue/main.cpp
Translation Unit Configurations:
[ /Users/Lars/Desktop/ColoringIssue/main.cpp ]:
    Process ID: 34495
    Memory Usage: 139 MB
    Compiler Path: /usr/bin/g++
    Includes:
        /usr/local/include
        /Library/Developer/CommandLineTools/SDKs/MacOSX11.3.sdk/usr/include/c++/v1
        /Library/Developer/CommandLineTools/usr/lib/clang/12.0.5/include
        /Library/Developer/CommandLineTools/SDKs/MacOSX11.3.sdk/usr/include
        /Library/Developer/CommandLineTools/usr/include
    Frameworks:
        /Library/Developer/CommandLineTools/SDKs/MacOSX11.3.sdk/System/Library/Frameworks
    Standard Version: c++20
    IntelliSense Mode: macos-clang-x64
    Other Flags:
        --clang
        --clang_version=110000
Total Memory Usage: 139 MB

------- Workspace parsing diagnostics -------
Number of files discovered (not excluded): 30097

• Logs from the language server logging

loggingLevel: Debug
loggingLevel has changed to: Debug
cpptools/didChangeCppProperties
$/setTraceNotification
cpptools/getCodeActions: /Users/Lars/Desktop/ColoringIssue/main.cpp (id: 82)
cpptools/textEditorSelectionChange
cpptools/textEditorSelectionChange
cpptools/activeDocumentChange: /Users/Lars/Desktop/ColoringIssue/main.cpp
cpptools/getFoldingRanges: /Users/Lars/Desktop/ColoringIssue/main.cpp (id: 83)
cpptools/textEditorSelectionChange
cpptools/textEditorSelectionChange
cpptools/activeDocumentChange: /Users/Lars/Desktop/ColoringIssue/main.cpp
willSaveWaitUntil: 0ms
textDocument/didSave: /Users/Lars/Desktop/ColoringIssue/main.cpp
  tag parsing file: /Users/Lars/Desktop/ColoringIssue/main.cpp
cpptools/fileChanged: /Users/Lars/Desktop/ColoringIssue/main.cpp
idle loop: reparsing the active document
Checking for syntax errors: /Users/Lars/Desktop/ColoringIssue/main.cpp
Queueing IntelliSense update for files in translation unit of: /Users/Lars/Desktop/ColoringIssue/main.cpp
cpptools/finishUpdateSquiggles
Error squiggle count: 0
Update IntelliSense time (sec): 0.258
cpptools/getSemanticTokens: /Users/Lars/Desktop/ColoringIssue/main.cpp (id: 85)
textDocument/didClose: /Users/Lars/Desktop/ColoringIssue/main.cpp
cpptools/getCodeActions: /Users/Lars/Desktop/ColoringIssue/main.cpp (id: 86)
textDocument/didOpen: /Users/Lars/Desktop/ColoringIssue/main.cpp
Checking for syntax errors: /Users/Lars/Desktop/ColoringIssue/main.cpp
Queueing IntelliSense update for files in translation unit of: /Users/Lars/Desktop/ColoringIssue/main.cpp
cpptools/textEditorSelectionChange
cpptools/getDocumentSymbols: /Users/Lars/Desktop/ColoringIssue/main.cpp (id: 87)
cpptools/textEditorSelectionChange
cpptools/getSemanticTokens: /Users/Lars/Desktop/ColoringIssue/main.cpp (id: 88)
cpptools/activeDocumentChange: /Users/Lars/Desktop/ColoringIssue/main.cpp
cpptools/getDocumentSymbols
cpptools/getFoldingRanges: /Users/Lars/Desktop/ColoringIssue/main.cpp (id: 89)
textDocument/hover: /Users/Lars/Desktop/ColoringIssue/main.cpp (id: 90)
Request canceled: 90
cpptools/finishUpdateSquiggles
Error squiggle count: 0
terminating child process: 34560
Update IntelliSense time (sec): 1.05
cpptools/getFoldingRanges: /Users/Lars/Desktop/ColoringIssue/main.cpp (id: 91)

Screenshots

Looks like the tokens given to the bracket are very wrong:

as compared to a normal for loop:

Start with the supplied main.cpp and reproduce the issue with C_Cpp.enhancedColorization set to Enabled. Inspect the semantic tokens reported for the custom iterator's range-based for loop and compare them with the normal loop; done means the brackets receive the expected colorization without introducing syntax errors.