Re: [patch] [gdb/testsuite] include a use of the definition of a type to cause clang to emit debug info

[David Blaikie <dblaikie at gmail dot com>]

Oh, and there was one other instance of the same issue (I believe
these are the only two cases)

This test case (gdb.cp/pr10728) seems like it could probably be
simplified a great deal, down to:

struct foo;
foo *f, *g;
int main() {
} // break and print f - g

if I'm not mistaken... - but I've made a relatively small change for
now. If preferred, I can make the more substantial simplification
suggested. Or otherwise appease clang (by introducing a use of the
original 'x' type definition in some other way - dereferencing a
pointer, etc).

- David

On Sat, Apr 12, 2014 at 11:43 PM, David Blaikie <dblaikie@gmail.com> wrote:
> Clang has an optimization that causes a the debug info to only include
> the declaration of a type if the type is referenced but never used in
> a context that requires a definition (eg: pointers are handed around
> but never deferenced).
>
> This patch introduces a variable to one test file to cause clang to
> emit the full definition of the type as well as fixing up a related
> typo in the test message of the associated expect file.
>
> Like the difference between GCC and Clang in the emission of unused
> static entities, I think this case is also a matter of degrees - both
> GCC and Clang implement other similar optimizations* to the one
> outlined here and the GDB test suite has managed to pass without
> disabling those optimizations in GCC and I hope it's suitable to do
> the same for Clang.
>
> Though admittedly I don't have much of the context of the history of
> the testsuite, its priorities/preferences when it comes to
> distinguishing testing compiler behavior versus debugger behavior,
> etc.
>
> * the one I know of involves dynamic types: both GCC and Clang only
> emit the debug info definition of such a type in any translation unit
> that emits the key function. This means in many contexts where a full
> definition is provided in the source only a declaration is provided in
> the debug info.

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