[PATCH] function try block handler redeclarations

[Richard Smith]

On Tue, May 27, 2014 at 6:57 AM, Aaron Ballman <aaron at aaronballman.com>
wrote:

> The exception-declaration for a function-try-block cannot redeclare a
> function parameter. One of our existing test cases was XFAILed because
> of this. This patch is an attempt to fix the issue and un-XFAIL the
> test.
>
> I am getting this from [basic.lookup.unqual]p15, which says,
>
> A name used in the handler for a function-try-block (Clause 15) is
> looked up as if the name was used in the outermost block of the
> function definition. In particular, the function parameter names shall
> not be redeclared in the exception-declaration nor in the outermost
> block of a handler for the function-try-block.


This looks like it might do the wrong thing for a function nested within
another function:

void f(int i) {
  struct S {
    void g() try {} catch (int i) {}; // shouldn't diagnose this, but I
think you will
  };
}

The way we generally handle this is in IdentifierResolver::isDeclInScope,
and that's the right place for this fix. You should be able to detect a
catch of a function try block by looking at the flags on the Scope.
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