[gcc r10-10071] Fortran: fix pointless warning for static variables

[gcc r10-10071] Fortran: fix pointless warning for static variables

[Harald Anlauf]

https://gcc.gnu.org/g:d9887f6d99fe435dd63e1c0eefa820b24c7f4100

commit r10-10071-gd9887f6d99fe435dd63e1c0eefa820b24c7f4100
Author: Harald Anlauf <anlauf@gmx.de>
Date:   Tue Aug 24 21:07:50 2021 +0200

    Fortran: fix pointless warning for static variables
    
    gcc/fortran/ChangeLog:
    
            PR fortran/98411
            * trans-decl.c (gfc_finish_var_decl): Adjust check to handle
            implicit SAVE as well as variables in the main program.  Improve
            warning message text.
    
    gcc/testsuite/ChangeLog:
    
            PR fortran/98411
            * gfortran.dg/pr98411.f90: Adjust testcase options to restrict to
            F2008, and verify case of implicit SAVE.
    
    (cherry picked from commit f95946afd160e2a1f4beac4ee5e6d5633307f39a)

Diff:
---
 gcc/fortran/trans-decl.c              | 20 +++++++++++++-------
 gcc/testsuite/gfortran.dg/pr98411.f90 |  4 +++-
 2 files changed, 16 insertions(+), 8 deletions(-)

diff --git a/gcc/fortran/trans-decl.c b/gcc/fortran/trans-decl.c
index bca15a51d99..27b4a9bc73d 100644
--- a/gcc/fortran/trans-decl.c
+++ b/gcc/fortran/trans-decl.c
@@ -736,8 +736,10 @@ gfc_finish_var_decl (tree decl, gfc_symbol * sym)
 
   /* Keep variables larger than max-stack-var-size off stack.  */
   if (!(sym->ns->proc_name && sym->ns->proc_name->attr.recursive)
+      && !(sym->ns->proc_name && sym->ns->proc_name->attr.is_main_program)
       && !sym->attr.automatic
       && sym->attr.save != SAVE_EXPLICIT
+      && sym->attr.save != SAVE_IMPLICIT
       && INTEGER_CST_P (DECL_SIZE_UNIT (decl))
       && !gfc_can_put_var_on_stack (DECL_SIZE_UNIT (decl))
 	 /* Put variable length auto array pointers always into stack.  */
@@ -750,13 +752,17 @@ gfc_finish_var_decl (tree decl, gfc_symbol * sym)
     {
       if (flag_max_stack_var_size > 0)
 	gfc_warning (OPT_Wsurprising,
-		     "Array %qs at %L is larger than limit set by"
-		     " %<-fmax-stack-var-size=%>, moved from stack to static"
-		     " storage. This makes the procedure unsafe when called"
-		     " recursively, or concurrently from multiple threads."
-		     " Consider using %<-frecursive%>, or increase the"
-		     " %<-fmax-stack-var-size=%> limit, or change the code to"
-		     " use an ALLOCATABLE array.",
+		     "Array %qs at %L is larger than limit set by "
+		     "%<-fmax-stack-var-size=%>, moved from stack to static "
+		     "storage. This makes the procedure unsafe when called "
+		     "recursively, or concurrently from multiple threads. "
+		     "Consider increasing the %<-fmax-stack-var-size=%> "
+		     "limit (or use %<-frecursive%>, which implies "
+		     "unlimited %<-fmax-stack-var-size%>) - or change the "
+		     "code to use an ALLOCATABLE array. If the variable is "
+		     "never accessed concurrently, this warning can be "
+		     "ignored, and the variable could also be declared with "
+		     "the SAVE attribute.",
 		     sym->name, &sym->declared_at);
 
       TREE_STATIC (decl) = 1;
diff --git a/gcc/testsuite/gfortran.dg/pr98411.f90 b/gcc/testsuite/gfortran.dg/pr98411.f90
index 249afaea419..7c906a96f60 100644
--- a/gcc/testsuite/gfortran.dg/pr98411.f90
+++ b/gcc/testsuite/gfortran.dg/pr98411.f90
@@ -1,5 +1,5 @@
 ! { dg-do compile }
-! { dg-options "-Wall -fautomatic -fmax-stack-var-size=100" }
+! { dg-options "-std=f2008 -Wall -fautomatic -fmax-stack-var-size=100" }
 ! PR fortran/98411 - Pointless warning for static variables 
 
 module try
@@ -9,8 +9,10 @@ contains
   subroutine initmodule
     real, save :: b(1000)
     logical    :: c(1000) ! { dg-warning "moved from stack to static storage" }
+    integer    :: e(1000) = 1
     a(1) = 42
     b(2) = 3.14
     c(3) = .true.
+    e(5) = -1
   end subroutine initmodule
 end module try