r193162 - Revert "This patch causes clang to reject alias attributes that point to undefined names. For example, with this patch we now reject"

[Alp Toker]

On 22/10/2013 15:23, Rafael Espindola wrote:
> Author: rafael
> Date: Tue Oct 22 09:23:09 2013
> New Revision: 193162
>
> URL: http://llvm.org/viewvc/llvm-project?rev=193162&view=rev
> Log:
> Revert "This patch causes clang to reject alias attributes that point to undefined names. For example, with this patch we now reject"
>
> This reverts commit r193161.
>
> It broke
>
> void foo() __attribute__((alias("bar")));
> void bar() {}
> void zed() __attribute__((alias("foo")));

FWIW, swapping the order of alias declarations makes a difference.

Fails:

|void foo() __attribute__((alias("bar")));||
||void zed() __attribute__((alias("foo")));||
||void bar() {}||
||al.c:3:27: error: alias must point to a defined variable or function||
||void zed() __attribute__((alias("foo")));||
||
||declare void @foo(...) #0||
||void (...)* bitcast (void ()* @bar to void (...)*)|


Works:

|void zed() __attribute__((alias("foo")));||
||void foo() __attribute__((alias("bar")));||
||void bar() {}||
||
||void (...)* bitcast (void ()* @bar to void (...)*)||
||@foo = alias bitcast (void ()* @bar to void (...)*)|


So I don't think any of the Sema changes for PR17639 can help.

Isn't it rather a question of getting CodeGen to emit the GlobalDecls in
the right order?

Alp.


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