[gcc r16-4107] Fortran: fix uninitialized read in testcase gfortran.dg/pdt_48.f03

[Harald Anlauf]

https://gcc.gnu.org/g:e6b4908c0402635c05e98bb1add0c4eaac44a02b

commit r16-4107-ge6b4908c0402635c05e98bb1add0c4eaac44a02b
Author: Harald Anlauf <anlauf@gmx.de>
Date:   Fri Sep 26 19:20:39 2025 +0200

    Fortran: fix uninitialized read in testcase gfortran.dg/pdt_48.f03
    
    Running the testcase using valgrind --leak-check=full --track-origins=yes:
    
    ==28585== Conditional jump or move depends on uninitialised value(s)
    ==28585==    at 0x400E19: MAIN__ (pdt_48.f03:48)
    ==28585==    by 0x400EDB: main (pdt_48.f03:34)
    ==28585==  Uninitialised value was created by a heap allocation
    ==28585==    at 0x4841984: malloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
    ==28585==    by 0x400975: __pdt_m_MOD_add (pdt_48.f03:30)
    ==28585==    by 0x400D84: MAIN__ (pdt_48.f03:44)
    ==28585==    by 0x400EDB: main (pdt_48.f03:34)
    
    The cause was a partial initialization of a vector used in a subsequent
    addition.  Initialize the remaining elements of the first vector by zero.
    
    gcc/testsuite/ChangeLog:
    
            * gfortran.dg/pdt_48.f03:

Diff:
---
 gcc/testsuite/gfortran.dg/pdt_48.f03 | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/gcc/testsuite/gfortran.dg/pdt_48.f03 b/gcc/testsuite/gfortran.dg/pdt_48.f03
index ed60b91c8c90..41b4b045cc15 100644
--- a/gcc/testsuite/gfortran.dg/pdt_48.f03
+++ b/gcc/testsuite/gfortran.dg/pdt_48.f03
@@ -16,17 +16,18 @@ contains
     integer :: c
     c=max(a,b)
   end function diy_max
-                
+
   function add(a,b) result(c)
     type(vec(k=*)), intent(in) :: a,b
     type(vec(k=max(a%k,b%k))) :: c      ! Fails
     !type(vec(k=diy_max(a%k,b%k))) :: c ! Worked with diy_max
     !type(vec(k=a%k+b%k)) :: c          ! Worked with +
-    
+
     c%foo(1:a%k)=a%foo
+    c%foo(a%k+1:) = 0
     c%foo(1:b%k)=c%foo(1:b%k)+b%foo
 
-    if (c%k /= 5) stop 1 
+    if (c%k /= 5) stop 1
   end function add
 end module pdt_m