1388807 - StackWalk.h can't be included from C files, despite claiming it is intended to be

Status: RESOLVED FIXED

(Core :: mozglue, defect)

Description

[Dana Keeler (she/her) (use needinfo) [:keeler] (on leave)]

StackWalk.h says: /* WARNING: This file is intended to be included from C or C++ files. */

and yet uses bool and namespace, which means it can't actually be included from C files.

Comment 1

[David Baron :dbaron: (⌚️UTC-4, no longer working on Mozilla)]

Yeah, we stopped actually testing that it could be included from C files when we removed trace-malloc in bug 1014341.

Comment 2

[Nathan Froyd [:froydnj]]

What do you need it to be callable from C code for?  It's probably not difficult to make things C-compatible, but it is a little unusual.

Comment 3

[Dana Keeler (she/her) (use needinfo) [:keeler] (on leave)]

I'm trying to debug a test failure that only reproduces on treeherder, so I wanted to dump some stack traces from NSS, which happens to be C. I later realized this wouldn't be possible since it would create a circular library dependency, so in this case it wouldn't help anyway. What I really want is a standalone utility function callable from pretty much anywhere that will dump the stack, but that's probably a bit out of scope here. For this bug, I think it might just be best to fix the documentation to not be misleading :)

Comment 4

[Nathan Froyd [:froydnj]]

Attachment: fix StackWalk.h documentation

We use C++ constructs in this file, we shouldn't advertise C
compatibility in the comments.

Comment 5

[Dana Keeler (she/her) (use needinfo) [:keeler] (on leave)]

Comment on attachment 8895474 [details] [diff] [review]
fix StackWalk.h documentation

Review of attachment 8895474 [details] [diff] [review]:
-----------------------------------------------------------------

Cool - thanks!

::: mozglue/misc/StackWalk.h
@@ -3,5 @@
>  /* This Source Code Form is subject to the terms of the Mozilla Public
>   * License, v. 2.0. If a copy of the MPL was not distributed with this
>   * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
>  
> -/* API for getting a stack trace of the C/C++ stack on the current thread */

There are a couple of other comments that reference the "C/C++ stack" of the current or other threads. I guess they're not technically wrong since while code using this API would be C++, there could be C frames on this/other threads? (although maybe they should all just say "stack trace" and not mention C/C++)

Comment 6

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/mozilla-inbound/rev/e5b80827a4db
fix StackWalk.h documentation; r=keeler

Comment 7

[Sebastian Hengst [:aryx] (needinfo me if it's about an intermittent or backout)]

https://hg.mozilla.org/mozilla-central/rev/e5b80827a4db