[PATCH] Avoid uninit warnings with Fortran optional args (PR fortran/52370)

[Jakub Jelinek]

Hi!

Optional dummy arg support vars are often undefined in various paths,
while the predicated uninit analysis can sometimes avoid false positives,
sometimes it can't.  So IMHO we should set TREE_NO_WARNING here, it is
already set on the other support vars like size.N, ubound.N, lbound.N, etc.
but not on the actual data pointer.

Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?

2014-02-11  Jakub Jelinek  <jakub@redhat.com>

	PR fortran/52370
	* trans-decl.c (gfc_build_dummy_array_decl): Set TREE_NO_WARNING
	on decl if sym->attr.optional.

	* gfortran.dg/pr52370.f90: New test.

--- gcc/fortran/trans-decl.c.jj	2014-01-03 11:40:53.000000000 +0100
+++ gcc/fortran/trans-decl.c	2014-02-11 18:17:47.315598566 +0100
@@ -1014,6 +1014,10 @@ gfc_build_dummy_array_decl (gfc_symbol *
   TREE_STATIC (decl) = 0;
   DECL_EXTERNAL (decl) = 0;
 
+  /* Avoid uninitialized warnings for optional dummy arguments.  */
+  if (sym->attr.optional)
+    TREE_NO_WARNING (decl) = 1;
+
   /* We should never get deferred shape arrays here.  We used to because of
      frontend bugs.  */
   gcc_assert (sym->as->type != AS_DEFERRED);
--- gcc/testsuite/gfortran.dg/pr52370.f90.jj	2014-02-11 18:20:45.704628460 +0100
+++ gcc/testsuite/gfortran.dg/pr52370.f90	2014-02-11 18:20:11.000000000 +0100
@@ -0,0 +1,21 @@
+! PR fortran/52370
+! { dg-do compile }
+! { dg-options "-O1 -Wall" }
+
+module pr52370
+contains
+  subroutine foo(a,b)
+    real, intent(out) :: a
+    real, dimension(:), optional, intent(out) :: b
+    a=0.5
+    if (present(b)) then
+      b=1.0
+    end if
+  end subroutine foo
+end module pr52370
+
+program prg52370
+  use pr52370
+  real :: a
+  call foo(a)
+end program prg52370

	Jakub