[PATCH, C++] Warn on redefinition of builtin functions (PR c++/71973)
Jason Merrill
jason@redhat.com
Tue Nov 1 15:02:00 GMT 2016
On 10/17/2016 03:18 PM, Bernd Edlinger wrote:
> Regarding this hunk:
>
> /* Whether or not the builtin can throw exceptions has no
> bearing on this declarator. */
> - TREE_NOTHROW (olddecl) = 0;
> + TREE_NOTHROW (olddecl) = TREE_NOTHROW (newdecl);
>
> You may ask, why the old code was working most of the time.
> I think, usually, when types_match == true, there happens another
> assignment to TREE_NOTHROW, later in that function around line 2183:
>
> /* Merge the type qualifiers. */
> if (TREE_READONLY (newdecl))
> TREE_READONLY (olddecl) = 1;
> if (TREE_THIS_VOLATILE (newdecl))
> TREE_THIS_VOLATILE (olddecl) = 1;
> if (TREE_NOTHROW (newdecl))
> TREE_NOTHROW (olddecl) = 1;
>
> This is in a big "if (types_match)", so I think that explains,
> why the old code did work normally, and why it fails if the
> parameter don't match, but I still have no idea what to say
> in the comment, except that the code should exactly do what
> the comment above says.
I think a better fix would be to add a copy of TREE_NOTHROW to the else
block of the if (types_match), to go with the existing copies of
TREE_READONLY and TREE_THIS_VOLATILE. But yes, duplicate_decls is a mess.
Jason
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