conversion operator of a template class reports invalid name

[geza-herman]

Observed behavior

ccls reports invalid name for the operator in this code:

template <typename TYPE>
struct Foo {
    operator Foo<const TYPE>() {
        return 0;
    }
};

It produces this json message:

{
    "jsonrpc": "2.0",
    "id": 2,
    "result": [
        {
            "name": "Foo",
            "detail": "struct Foo {}",
            "kind": 23,
            "range": {
                [[[snip]]]
            },
            "selectionRange": {
                [[[snip]]]
            },
            "children": [
                {
                    "name": "operator Foo<const TYPE>()\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000",
                    "detail": "operator Foo<const TYPE>()",
                    "kind": 6,
                    "range": {
                        [[[snip]]]
                    },
                    "selectionRange": {
                        [[[snip]]]
                    },
                    "children": []
                }
            ]
        }
    ]
}

Note the embedded \0 characters in the name for the operator. I debugged the issue a little bit, and the problem is that in IndexDataConsumer::setName, detailed_name contains a string which has TYPE as the template parameter, but short_name contains type-parameter-0-0. So later when short_name_size is used to index detailed_name, it creates a std::string_view which over-reads the detailed_name string.

Note: if I remove const, then it works OK.

Expected behavior

name should be properly reported.

Steps to reproduce

This happens for me with lsp-mode in emacs. Save my example cpp file, and load it into emacs with lsp-mode. A json parse error will be generated for the name because of the \0 characters:

Warning (lsp-mode): Failed to parse the following chunk:
[[[snip, the bad json is printed here]]]
with message (json-parse-error \u0000 is not allowed without JSON_ALLOW_NUL <callback> 1 361 361) Disable showing Disable logging

System information

• ccls version: 0.20210330-3-g92eba29a
• clang version: 11
• OS: Linux
• Editor: emacs
• Language client (and version): lsp-mode