textDocument/hover: no documentation from system include paths

[saladpanda]

Observed behavior

on textDocument/hover ccls does not provide documentation for functions from system include paths.
Documentation is only provided for local includes.

Expected behavior

ccls should provide documentation for all symbols on textDocument/hover.

Steps to reproduce

Minimal example:

// a.h

#include "b.h"
#include <stdio.h>

void test() {
    foobar(5);
    printf("Hello world");
}

// b.h

/* This is helpful documentation
 *
 * param i: ignored
 * returns: nothing
 */
void foobar(int i) {
    return;
}

in a.h trigger a hover on foobar and then on printf. This is the strace log (annotated):

# Triggering hover on foobar. Answer contains documentation.
[pid 26942] read(0, "Content-Length: 160\r\n\r\n{\"jsonrpc\":\"2.0\",\"method\":\"textDocument/hover\",\"params\":{\"position\":{\"character\":5,\"line\":6},\"textDocument\":{\"uri\":\"file:///tmp/ccls-test-project/a.h\"}},\"id\":2}", 4096) = 183
[pid 26942] read(0,  <unfinished ...>
[pid 26943] write(1, "Content-Length: 239\r\n\r\n{\"jsonrpc\":\"2.0\",\"id\":2,\"result\":{\"contents\":[\"This is helpful documentation\\n\\nparam i: ignored\\nreturns: nothing\",{\"language\":\"c\",\"value\":\"void foobar(int i)\"}],\"range\":{\"start\":{\"line\":6,\"character\":4},\"end\":{\"line\":6,\"character\":10}}}}", 262) = 262

# Triggering hover on printf. Just signature returned, no documentation.
[pid 26942] <... read resumed>"Content-Length: 160\r\n\r\n{\"jsonrpc\":\"2.0\",\"method\":\"textDocument/hover\",\"params\":{\"position\":{\"character\":5,\"line\":7},\"textDocument\":{\"uri\":\"file:///tmp/ccls-test-project/a.h\"}},\"id\":3}", 4096) = 183
[pid 26942] read(0,  <unfinished ...>
[pid 26943] write(1, "Content-Length: 206\r\n\r\n{\"jsonrpc\":\"2.0\",\"id\":3,\"result\":{\"contents\":[{\"language\":\"c\",\"value\":\"extern int printf(const char *__restrict __format, ...)\"}],\"range\":{\"start\":{\"line\":7,\"character\":4},\"end\":{\"line\":7,\"character\":10}}}}", 229) = 229

/usr/include/stdio.h does contain documentation:

...
/* Write formatted output to stdout.

   This function is a possible cancellation point and therefore not
   marked with __THROW.  */
extern int printf (const char *__restrict __format, ...);
...

System information

• ccls version: 0.20190314
• clang version: 8.0.0
• OS: Manjaro Linux
• Editor: vim
• Language client (and version): https://github.com/autozimu/LanguageClient-neovim

relevant .vimrc excerpt:

let g:LanguageClient_serverCommands = {
    \ 'cpp': ['/bin/ccls',
    \ '--log-file=/tmp/ccls.log',
    \ '--init={"cache": {"directory": "$HOME/.cache/ccls"}}'],
\ }

[MaskRay]

Nice report!

--init={"cache": {"directory": "$HOME/.cache/ccls"}}'

Note ccls doesn't expand shell-style $. You are relying on the language client to do that for you.

[saladpanda]

I'm afraid this does not fix the issue as I'm still not getting documentation for printf.

The problem seems to not be related to system headers.
I tried copying /usr/include/stdio.h into my test directory as mystdio.h and changed the include in a.h to #include "mystdio.h".
Still not getting the doc-comment for printf.