[C++ PATCH] Fix PR58705

[Marek Polacek]

Ping.

On Mon, Oct 14, 2013 at 02:23:59PM +0200, Marek Polacek wrote:
> We were ICEing on the attached testcase, because in check_narrowing,
> for = {{}}, we wanted to check recursively the CONSTRUCTOR_ELTs,
> even though init in this case has 0 CONSTRUCTOR_NELTS.  So I added
> the check for CONSTRUCTOR_NELTS > 0.  Moreover, since empty scalar
> initializers are forbidden in C FE, I think we should error out here
> too.  (Complex type is considered as an arithmetic type as a GNU
> extension and arithmetic types are scalar types.)
> This isn't C++11-specific as it may look from the PR.  The bug
> exhibits when -Wnarrowing (that is implicitly enabled with C++11) is
> on, since in check_narrowing we have
> 
>   if (!warn_narrowing || !ARITHMETIC_TYPE_P (type))
>       return;
> 
> and with -Wno-narrowing we just return early.
> 
> Regtested/bootstrapped on x86_64-linux, ok for trunk?
> 
> 2013-10-14  Marek Polacek  <polacek@redhat.com>
> 
> 	PR c++/58705
> cp/
> 	* typeck2.c (check_narrowing): Give an error when the scalar
> 	initializer is empty.
> testsuite/
> 	* g++.dg/parse/pr58705.C: New test.
> 
> --- gcc/cp/typeck2.c.mp	2013-10-14 11:11:36.971293089 +0200
> +++ gcc/cp/typeck2.c	2013-10-14 11:52:14.582061052 +0200
> @@ -833,7 +833,10 @@ check_narrowing (tree type, tree init)
>        && TREE_CODE (type) == COMPLEX_TYPE)
>      {
>        tree elttype = TREE_TYPE (type);
> -      check_narrowing (elttype, CONSTRUCTOR_ELT (init, 0)->value);
> +      if (CONSTRUCTOR_NELTS (init) > 0)
> +	check_narrowing (elttype, CONSTRUCTOR_ELT (init, 0)->value);
> +      else
> +	error ("empty scalar initializer");
>        if (CONSTRUCTOR_NELTS (init) > 1)
>  	check_narrowing (elttype, CONSTRUCTOR_ELT (init, 1)->value);
>        return;
> --- gcc/testsuite/g++.dg/parse/pr58705.C.mp	2013-10-14 11:14:46.460955343 +0200
> +++ gcc/testsuite/g++.dg/parse/pr58705.C	2013-10-14 11:51:02.698810118 +0200
> @@ -0,0 +1,5 @@
> +// PR c++/58705
> +// { dg-do compile }
> +// { dg-options "-Wnarrowing" }
> +
> +_Complex float f = {{}};  // { dg-error "empty scalar initializer" }
> 
> 	Marek

	Marek