feat(diagnostics): support pull diagnostics or document push-only behavior

[yhcedpn]

Related area

Diagnostics
Configuration

Description

clice currently produces C++ compiler diagnostics during translation-unit compilation, but it does not implement the standard LSP textDocument/diagnostic request. A client requesting document diagnostics receives -32601: method not found.

The server capabilities also do not advertise a diagnosticProvider. This makes clice diagnostics inaccessible to clients that use the pull-diagnostics API instead of consuming textDocument/publishDiagnostics notifications.

This report is about the LSP diagnostic contract, not Visual Studio-specific VCR#### rules. A generic C++ LSP client should not be expected to reproduce Visual Studio's proprietary code-style diagnostic IDs.

Steps to reproduce

1. Start clice for a Windows MSVC project with a valid compile_commands.json.
2. Initialize the server with a standard LSP client.
3. Open a C++ translation unit containing a deliberate semantic error such as an unknown type.
4. Request textDocument/diagnostic for the document, both without an identifier and with identifiers such as DocumentCompilerSemantic or DocumentAnalyzerSemantic.
5. Observe -32601: method not found: textDocument/diagnostic.
6. Observe from the clice session log that compilation still produces diagnostics.

A minimal probe can be as small as:

int diagnostic_probe()
{
    UnknownType value{};
    return value.member;
}

Motivation

Please either:

• implement standard LSP pull diagnostics and advertise diagnosticProvider, including stable source/code/severity/range fields; or
• document clearly that clice is push-only for diagnostics and specify the expected publishDiagnostics behavior and payload.

Supporting pull diagnostics would make clice interoperable with generic LSP clients. If push-only is intentional, documenting it would prevent clients from treating method not found as an empty diagnostic result.

The existing clang-tidy tracking issue is related to analyzer coverage, but this report concerns the LSP transport and discoverability of diagnostics.

[yhcedpn]

关联 Issue 在这里 can1357/oh-my-pi#10787
我用 ohmypi 的时候发现的。
至于 VCR003 这种提示大概率是 VS 生态专属，只能手动搞了。