compiletest: cdb version detection locally seems funky

[jieyouxu]

While investigating #133107, it seems that even if I have a suitably-versioned cdb e.g. 10.0.26100.2161 in PATH, compiletest cdb version detection seems to consider that I failed to satisfy

//@ min-cdb-version: 10.0.26100.2161

[ChrisDenton]

Looks like it just hard codes the path, aside from using ProgramFiles(x86) environment variable as the base directory:

rust/src/tools/compiletest/src/debuggers.rs

Line 79 in 46e8d20

fn find_cdb(target: &str) -> Option<OsString> {

[jieyouxu]

That's kinda what I expected yeah. On one hand it saves you from having to manually specify it in PATH. On the other hand...

[ChrisDenton]

The simplest fix would be to check PATH first then fallback. However, it would be important to make sure that doesn't cause issues. E.g. we had problems with there being a msys2 link.exe that is not at all related to msvc's link.exe.

[ChrisDenton]

That said, I would note that there is a --cdb option for providing a path manually.

[jieyouxu]

That said, I would note that there is a --cdb option for providing a path manually.

AFAIK compiletest's cli are mostly for use by bootstrap, I'm not sure if that actually works. Maybe ./x test debuginfo -- --cdb=... but I haven't double-checked yet.

[ChrisDenton]

x test debuginfo --test-args --cdb=... should always work, no? The purpose of --test-args is to ensure arguments are passed through.

[jieyouxu]

Ah right. Forgot about that.

[hkBst]

What doc changes would you like to see here?

[jieyouxu]

Something simple like the following would go a long way:

• That cdb detection will look for a local cdb through a hard-coded search under ProgramFiles(x86) or ProgramFiles depending on host, and does not respect PATH.
• How to pass a custom cdb, e.g. ./x test debuginfo --test-args --cdb=....

Probably send the doc PR against rustc-dev-guide and not here.