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* [Patch] Fortran: Avoid var initialization in interfaces [PR54753]
@ 2021-09-29  8:53 Tobias Burnus
  2021-09-29 20:10 ` Harald Anlauf
                   ` (2 more replies)
  0 siblings, 3 replies; 9+ messages in thread
From: Tobias Burnus @ 2021-09-29  8:53 UTC (permalink / raw)
  To: gcc-patches, fortran

[-- Attachment #1: Type: text/plain, Size: 1854 bytes --]

Found when looking at F2018:C839 / PR54753.

For INTENT(OUT) the dummy variable (might) also be default initialized
or deallocated. However, with assumed rank, that causes issues, which
C839 prevents. In the current GCC implementation, missing C839 constraint
diagnostic, but also rejects-valid/ice-on-valid appears.

There are three issues, this patch solves the first:

* reject-valid issue due to adding the initializer also to a dummy
   argument which is in an INTERFACE block. Having initializers in
   INTERFACE blocks is pointless and causes for the attached testcase
   the bogus error:
   "Assumed-rank variable y at (1) may only be used as actual argument"

(Except for wasting resources and this error, they should be ignored
in trans*.c and usually do not cause any further harm.)


I think Sandra has a nearly ready patch to do the C839 constraint
diagnostic, which needs the attached patch to do the checks.

The third issue is that GCC currently gives either an ICE or the
above error message when declaring a procedure with a valid
assumed-rank intent(out) dummy. This has still to be solved as well.
But first I wanted to unblock Sandra's C839 work with this patch :-)


Regarding the patch, '!= IFSRC_IFBODY' has to be used; "== IFSRC_DECL"
won't work as the the generatedy ENTRY master function has IFSRC_UNKNOWN.

OK for mainline?

Tobias

PS: Some patch reviews are that fast that it is impossible to send the OK;
at least, I did not manage to do for Harald's last two - for the last one
I was at least 4min too late. ;-)

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[-- Attachment #2: intent-out.diff --]
[-- Type: text/x-patch, Size: 3185 bytes --]

Fortran: Avoid var initialization in interfaces [PR54753]

Intent(out) implies deallocation/default initialization; however, it is
pointless to do this for dummy-arguments symbols of procedures which are
inside an INTERFACE block. – This also fixes a bogus error for the attached
included testcase, but fixing the non-interface version still has to be done.

	PR fortran/54753

gcc/fortran/ChangeLog:

	* resolve.c (can_generate_init, resolve_fl_variable_derived,
	resolve_symbol): Only do initialization with intent(out) if not
	inside of an interface block.

gcc/testsuite/ChangeLog:

	* gfortran.dg/assumed_rank_23.f90: New test.

 gcc/fortran/resolve.c                         | 11 ++++++++---
 gcc/testsuite/gfortran.dg/assumed_rank_23.f90 | 16 ++++++++++++++++
 2 files changed, 24 insertions(+), 3 deletions(-)

diff --git a/gcc/fortran/resolve.c b/gcc/fortran/resolve.c
index 30b96b2f597..5d2478d9b96 100644
--- a/gcc/fortran/resolve.c
+++ b/gcc/fortran/resolve.c
@@ -12676,7 +12676,8 @@ can_generate_init (gfc_symbol *sym)
     || a->cray_pointer
     || sym->assoc
     || (!a->referenced && !a->result)
-    || (a->dummy && a->intent != INTENT_OUT)
+    || (a->dummy && (a->intent != INTENT_OUT
+		     || sym->ns->proc_name->attr.if_source != IFSRC_DECL))
     || (a->function && sym != sym->result)
   );
 }
@@ -12913,7 +12914,9 @@ resolve_fl_variable_derived (gfc_symbol *sym, int no_init_flag)
 
   /* Assign default initializer.  */
   if (!(sym->value || sym->attr.pointer || sym->attr.allocatable)
-      && (!no_init_flag || sym->attr.intent == INTENT_OUT))
+      && (!no_init_flag
+	  || (sym->attr.intent == INTENT_OUT
+	      && sym->ns->proc_name->attr.if_source == IFSRC_DECL)))
     sym->value = gfc_generate_initializer (&sym->ts, can_generate_init (sym));
 
   return true;
@@ -16154,7 +16157,8 @@ resolve_symbol (gfc_symbol *sym)
 		    || sym->ts.u.derived->attr.alloc_comp
 		    || sym->ts.u.derived->attr.pointer_comp))
 	   && !(a->function && sym != sym->result))
-	  || (a->dummy && a->intent == INTENT_OUT && !a->pointer))
+	  || (a->dummy && !a->pointer && a->intent == INTENT_OUT
+	      && sym->ns->proc_name->attr.if_source == IFSRC_DECL))
 	apply_default_init (sym);
       else if (a->function && sym->result && a->access != ACCESS_PRIVATE
 	       && (sym->ts.u.derived->attr.alloc_comp
@@ -16166,6 +16170,7 @@ resolve_symbol (gfc_symbol *sym)
 
   if (sym->ts.type == BT_CLASS && sym->ns == gfc_current_ns
       && sym->attr.dummy && sym->attr.intent == INTENT_OUT
+      && sym->ns->proc_name->attr.if_source == IFSRC_DECL
       && !CLASS_DATA (sym)->attr.class_pointer
       && !CLASS_DATA (sym)->attr.allocatable)
     apply_default_init (sym);
diff --git a/gcc/testsuite/gfortran.dg/assumed_rank_23.f90 b/gcc/testsuite/gfortran.dg/assumed_rank_23.f90
new file mode 100644
index 00000000000..c83aa7de1a3
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/assumed_rank_23.f90
@@ -0,0 +1,16 @@
+! { dg-do compile }
+!
+! PR fortran/54753
+! TS29113:C535c
+! F2018:C839
+!
+module m
+
+  interface
+    subroutine s1 (x, y)
+      class(*) :: x(..)
+      class(*), intent (out) :: y(..)
+    end subroutine
+  end interface
+
+end module 

^ permalink raw reply	[flat|nested] 9+ messages in thread
end of thread, other threads:[~2021-10-02 22:40 UTC | newest]

Thread overview: 9+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2021-09-29  8:53 [Patch] Fortran: Avoid var initialization in interfaces [PR54753] Tobias Burnus
2021-09-29 20:10 ` Harald Anlauf
2021-10-01 18:50 ` Harald Anlauf
2021-10-02 18:01 ` Sandra Loosemore
2021-10-02 18:29   ` Tobias Burnus
2021-10-02 19:19     ` Harald Anlauf
2021-10-02 19:56     ` Tobias Burnus
2021-10-02 20:28       ` Harald Anlauf
2021-10-02 22:40         ` Sandra Loosemore

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