diff mbox series

[v2,2/2] fortran: Fix specification expression error with dummy procedures [PR111781]

Message ID 20240317165749.1003825-3-mikael@gcc.gnu.org
State New
Headers show
Series fortran: Fix specification checks [PR111781] | expand

Commit Message

Mikael Morin March 17, 2024, 4:57 p.m. UTC 
This fixes a spurious invalid variable in specification expression error.
The problem is caused by improper restoration of formal_arg_flag to false
(instead of restoring it to its previous value).  This happens with the
testcase from the PR where a dummy argument is itself a procedure with dummy
arguments.  At the time that dummy procedure has been resolved, its dummy
arguments have been resolved and the flag has been reset to false.  The
condition checking that flag when resolving the array spec expressions of
the next dummy then triggers the error.

The fix removes a condition disabling proper check of specification
expressions, together with the formal_arg_flag global variable associated
with it.  As the specification expression checking code is dependent on the
current namespace, the latter is set before array spec resolution (and
restored after).  Two new functions are introduced to select the right
namespace for that.

	PR fortran/111781

gcc/fortran/ChangeLog:

	* symbol.cc (gfc_get_procedure_ns, gfc_get_spec_ns): New functions.
	* gfortran.h (gfc_get_procedure_ns, gfc_get_spec ns): Declare them.
	(gfc_is_formal_arg): Remove.
	* expr.cc (check_restricted): Remove the case where symbol is dummy
	and declared in the current ns.  Use gfc_get_spec_ns to get the
	right namespace.
	* resolve.cc (gfc_is_formal_arg, formal_arg_flag): Remove.
	(gfc_resolve_formal_arglist): Set gfc_current_ns.  Quit loop and
	restore gfc_current_ns instead of early returning.
	(resolve_symbol): Factor common array spec resolution code to...
	(resolve_symbol_array_spec): ... this new function.  Additionnally
	set and restore gfc_current_ns.

gcc/testsuite/ChangeLog:

	* gfortran.dg/spec_expr_8.f90: New test.
	* gfortran.dg/spec_expr_9.f90: New test.
---
 gcc/fortran/expr.cc                       |  8 +--
 gcc/fortran/gfortran.h                    |  4 +-
 gcc/fortran/resolve.cc                    | 77 +++++++++++------------
 gcc/fortran/symbol.cc                     | 58 +++++++++++++++++
 gcc/testsuite/gfortran.dg/spec_expr_8.f90 | 24 +++++++
 gcc/testsuite/gfortran.dg/spec_expr_9.f90 | 19 ++++++
 6 files changed, 140 insertions(+), 50 deletions(-)
 create mode 100644 gcc/testsuite/gfortran.dg/spec_expr_8.f90
 create mode 100644 gcc/testsuite/gfortran.dg/spec_expr_9.f90

Comments

Harald Anlauf March 17, 2024, 8:57 p.m. UTC | #1 
Hi Mikael,

thanks for the patch!

Regarding the first part of the patch, I think that fixing bad testcases
can be done at any time.  Retaining identified, broken testcases means
that one may hit bogus regressions, hindering progress.

The second part of the patch looks at first glance fine to me.  And as
the patch changes less than its size suggests, in particular due to
code refactoring, I don't see a reason to postpone it to stage 1.

(On the contrary, deferring it to stage 1 might make future backports
from 15 for later patches on top of that code harder.
This is my opinion, and others might see this differently.)

On 3/17/24 17:57, Mikael Morin wrote:
> 	* expr.cc (check_restricted): Remove the case where symbol is dummy
> 	and declared in the current ns.  Use gfc_get_spec_ns to get the
> 	right namespace.

Looking at the original and new code, I don't fully understand
that part of the commit message: the changed check comes into play
when the symbol is *not* in_common, ..., a dummy, ...
So technically, we didn't access the (now removed) formal_arg_flag
here in those cases.
Or am I missing something?

> diff --git a/gcc/fortran/expr.cc b/gcc/fortran/expr.cc
> index 82a642b01f7..0852bc5f493 100644
> --- a/gcc/fortran/expr.cc
> +++ b/gcc/fortran/expr.cc
> @@ -3509,19 +3509,13 @@ check_restricted (gfc_expr *e)
>         if (!check_references (e->ref, &check_restricted))
>   	break;
>   
> -      /* gfc_is_formal_arg broadcasts that a formal argument list is being
> -	 processed in resolve.cc(resolve_formal_arglist).  This is done so
> -	 that host associated dummy array indices are accepted (PR23446).
> -	 This mechanism also does the same for the specification expressions
> -	 of array-valued functions.  */
>         if (e->error
>   	    || sym->attr.in_common
>   	    || sym->attr.use_assoc
>   	    || sym->attr.dummy
>   	    || sym->attr.implied_index
>   	    || sym->attr.flavor == FL_PARAMETER
> -	    || is_parent_of_current_ns (sym->ns)
> -	    || (gfc_is_formal_arg () && (sym->ns == gfc_current_ns)))
> +	    || is_parent_of_current_ns (gfc_get_spec_ns (sym)))
>   	{
>   	  t = true;
>   	  break;


> diff --git a/gcc/testsuite/gfortran.dg/spec_expr_8.f90 b/gcc/testsuite/gfortran.dg/spec_expr_8.f90
> new file mode 100644
> index 00000000000..5885810d421
> --- /dev/null
> +++ b/gcc/testsuite/gfortran.dg/spec_expr_8.f90
> @@ -0,0 +1,24 @@
> +! { dg-do compile }
> +!
> +! PR fortran/111781
> +! We used to reject the example below because the dummy procedure g was
> +! setting the current namespace without properly restoring it, which broke
> +! the specification expression check for the dimension of A later on.
> +!
> +! Contributed by Markus Vikhamar-Sandberg  <rasmus.vikhamar-sandberg@uit.no>

Is the reporter's first name Markus or Rasmus?


Thanks,
Harald
Mikael Morin March 17, 2024, 9:39 p.m. UTC | #2 
Le 17/03/2024 à 21:57, Harald Anlauf a écrit :
> Hi Mikael,
> 
> thanks for the patch!
> 
> Regarding the first part of the patch, I think that fixing bad testcases
> can be done at any time.  Retaining identified, broken testcases means
> that one may hit bogus regressions, hindering progress.
> 
> The second part of the patch looks at first glance fine to me.  And as
> the patch changes less than its size suggests, in particular due to
> code refactoring, I don't see a reason to postpone it to stage 1.
> 
What worries me a bit is the changes of gfc_current_ns.
It's the kind of change that has broad impact and can uncover weird 
behaviors.

> (On the contrary, deferring it to stage 1 might make future backports
> from 15 for later patches on top of that code harder.
> This is my opinion, and others might see this differently.)
> 
To be honest, I posted it now in the hope that someone would be willing 
to push it before stage 1 so that I can get rid of it sooner.

> On 3/17/24 17:57, Mikael Morin wrote:
>>     * expr.cc (check_restricted): Remove the case where symbol is dummy
>>     and declared in the current ns.  Use gfc_get_spec_ns to get the
>>     right namespace.
> 
> Looking at the original and new code, I don't fully understand
> that part of the commit message: the changed check comes into play
> when the symbol is *not* in_common, ..., a dummy, ...
> So technically, we didn't access the (now removed) formal_arg_flag
> here in those cases.
> Or am I missing something?
> 
Oh, do you really read all of my prose?
I wrote it from vague memories of debugging the problem weeks ago, 
without thinking very much about it.

Actually, there are two dummy arguments here.
There is the one we are checking, and its bounds should be a 
specification expression, so could possibly be another dummy variable 
(the "sym" variable in this context).
The condition was allowing variables declared in the same scope to 
appear in specification expression of dummy arguments.

I will try to rephrase the sentence, as it sounds more clear (and 
sensible) as expressed here.

>> diff --git a/gcc/fortran/expr.cc b/gcc/fortran/expr.cc
>> index 82a642b01f7..0852bc5f493 100644
>> --- a/gcc/fortran/expr.cc
>> +++ b/gcc/fortran/expr.cc
>> @@ -3509,19 +3509,13 @@ check_restricted (gfc_expr *e)
>>         if (!check_references (e->ref, &check_restricted))
>>       break;
>>
>> -      /* gfc_is_formal_arg broadcasts that a formal argument list is 
>> being
>> -     processed in resolve.cc(resolve_formal_arglist).  This is done so
>> -     that host associated dummy array indices are accepted (PR23446).
>> -     This mechanism also does the same for the specification expressions
>> -     of array-valued functions.  */
>>         if (e->error
>>           || sym->attr.in_common
>>           || sym->attr.use_assoc
>>           || sym->attr.dummy
>>           || sym->attr.implied_index
>>           || sym->attr.flavor == FL_PARAMETER
>> -        || is_parent_of_current_ns (sym->ns)
>> -        || (gfc_is_formal_arg () && (sym->ns == gfc_current_ns)))
>> +        || is_parent_of_current_ns (gfc_get_spec_ns (sym)))
>>       {
>>         t = true;
>>         break;
> 
> 
>> diff --git a/gcc/testsuite/gfortran.dg/spec_expr_8.f90 
>> b/gcc/testsuite/gfortran.dg/spec_expr_8.f90
>> new file mode 100644
>> index 00000000000..5885810d421
>> --- /dev/null
>> +++ b/gcc/testsuite/gfortran.dg/spec_expr_8.f90
>> @@ -0,0 +1,24 @@
>> +! { dg-do compile }
>> +!
>> +! PR fortran/111781
>> +! We used to reject the example below because the dummy procedure g was
>> +! setting the current namespace without properly restoring it, which 
>> broke
>> +! the specification expression check for the dimension of A later on.
>> +!
>> +! Contributed by Markus Vikhamar-Sandberg  
>> <rasmus.vikhamar-sandberg@uit.no>
> 
> Is the reporter's first name Markus or Rasmus?
> 
Rasmus.
Reviews are sometimes helpful, more often than not.
I don't know where the Markus name comes from.

Thanks for the review.
diff mbox series

Patch

diff --git a/gcc/fortran/expr.cc b/gcc/fortran/expr.cc
index 82a642b01f7..0852bc5f493 100644
--- a/gcc/fortran/expr.cc
+++ b/gcc/fortran/expr.cc
@@ -3509,19 +3509,13 @@  check_restricted (gfc_expr *e)
       if (!check_references (e->ref, &check_restricted))
 	break;
 
-      /* gfc_is_formal_arg broadcasts that a formal argument list is being
-	 processed in resolve.cc(resolve_formal_arglist).  This is done so
-	 that host associated dummy array indices are accepted (PR23446).
-	 This mechanism also does the same for the specification expressions
-	 of array-valued functions.  */
       if (e->error
 	    || sym->attr.in_common
 	    || sym->attr.use_assoc
 	    || sym->attr.dummy
 	    || sym->attr.implied_index
 	    || sym->attr.flavor == FL_PARAMETER
-	    || is_parent_of_current_ns (sym->ns)
-	    || (gfc_is_formal_arg () && (sym->ns == gfc_current_ns)))
+	    || is_parent_of_current_ns (gfc_get_spec_ns (sym)))
 	{
 	  t = true;
 	  break;
diff --git a/gcc/fortran/gfortran.h b/gcc/fortran/gfortran.h
index 32b792f85fb..f954b7a8802 100644
--- a/gcc/fortran/gfortran.h
+++ b/gcc/fortran/gfortran.h
@@ -3605,6 +3605,9 @@  bool gfc_is_associate_pointer (gfc_symbol*);
 gfc_symbol * gfc_find_dt_in_generic (gfc_symbol *);
 gfc_formal_arglist *gfc_sym_get_dummy_args (gfc_symbol *);
 
+gfc_namespace * gfc_get_procedure_ns (gfc_symbol *);
+gfc_namespace * gfc_get_spec_ns (gfc_symbol *);
+
 /* intrinsic.cc -- true if working in an init-expr, false otherwise.  */
 extern bool gfc_init_expr_flag;
 
@@ -3813,7 +3816,6 @@  bool gfc_resolve_iterator (gfc_iterator *, bool, bool);
 bool find_forall_index (gfc_expr *, gfc_symbol *, int);
 bool gfc_resolve_index (gfc_expr *, int);
 bool gfc_resolve_dim_arg (gfc_expr *);
-bool gfc_is_formal_arg (void);
 bool gfc_resolve_substring (gfc_ref *, bool *);
 void gfc_resolve_substring_charlen (gfc_expr *);
 gfc_expr *gfc_expr_to_initialize (gfc_expr *);
diff --git a/gcc/fortran/resolve.cc b/gcc/fortran/resolve.cc
index 02acc4aef31..6bdb56038bb 100644
--- a/gcc/fortran/resolve.cc
+++ b/gcc/fortran/resolve.cc
@@ -72,9 +72,6 @@  static bool first_actual_arg = false;
 
 static int omp_workshare_flag;
 
-/* True if we are processing a formal arglist. The corresponding function
-   resets the flag each time that it is read.  */
-static bool formal_arg_flag = false;
 
 /* True if we are resolving a specification expression.  */
 static bool specification_expr = false;
@@ -89,12 +86,6 @@  static bitmap_obstack labels_obstack;
 static bool inquiry_argument = false;
 
 
-bool
-gfc_is_formal_arg (void)
-{
-  return formal_arg_flag;
-}
-
 /* Is the symbol host associated?  */
 static bool
 is_sym_host_assoc (gfc_symbol *sym, gfc_namespace *ns)
@@ -285,7 +276,8 @@  gfc_resolve_formal_arglist (gfc_symbol *proc)
       sym->attr.always_explicit = 1;
     }
 
-  formal_arg_flag = true;
+  gfc_namespace *orig_current_ns = gfc_current_ns;
+  gfc_current_ns = gfc_get_procedure_ns (proc);
 
   for (f = proc->formal; f; f = f->next)
     {
@@ -306,17 +298,18 @@  gfc_resolve_formal_arglist (gfc_symbol *proc)
 		       &proc->declared_at);
 	  continue;
 	}
-      else if (sym->attr.procedure && sym->attr.if_source != IFSRC_DECL
+
+      if (sym->attr.procedure && sym->attr.if_source != IFSRC_DECL
 	       && !resolve_procedure_interface (sym))
-	return;
+	break;
 
       if (strcmp (proc->name, sym->name) == 0)
-        {
-          gfc_error ("Self-referential argument "
-                     "%qs at %L is not allowed", sym->name,
-                     &proc->declared_at);
-          return;
-        }
+	{
+	  gfc_error ("Self-referential argument "
+		     "%qs at %L is not allowed", sym->name,
+		     &proc->declared_at);
+	  break;
+	}
 
       if (sym->attr.if_source != IFSRC_UNKNOWN)
 	gfc_resolve_formal_arglist (sym);
@@ -533,7 +526,8 @@  gfc_resolve_formal_arglist (gfc_symbol *proc)
 	    }
 	}
     }
-  formal_arg_flag = false;
+
+  gfc_current_ns = orig_current_ns;
 }
 
 
@@ -15968,6 +15962,26 @@  resolve_pdt (gfc_symbol* sym)
 }
 
 
+/* Resolve the symbol's array spec.  */
+
+static bool
+resolve_symbol_array_spec (gfc_symbol *sym, int check_constant)
+{
+  gfc_namespace *orig_current_ns = gfc_current_ns;
+  gfc_current_ns = gfc_get_spec_ns (sym);
+
+  bool saved_specification_expr = specification_expr;
+  specification_expr = true;
+
+  bool result = gfc_resolve_array_spec (sym->as, check_constant);
+
+  specification_expr = saved_specification_expr;
+  gfc_current_ns = orig_current_ns;
+
+  return result;
+}
+
+
 /* Do anything necessary to resolve a symbol.  Right now, we just
    assume that an otherwise unknown symbol is a variable.  This sort
    of thing commonly happens for symbols in module.  */
@@ -15982,7 +15996,6 @@  resolve_symbol (gfc_symbol *sym)
   gfc_component *c;
   symbol_attribute class_attr;
   gfc_array_spec *as;
-  bool saved_specification_expr;
 
   if (sym->resolve_symbol_called >= 1)
     return;
@@ -16147,16 +16160,7 @@  resolve_symbol (gfc_symbol *sym)
 	}
     }
   else if (mp_flag && sym->attr.flavor == FL_PROCEDURE && sym->attr.function)
-    {
-      bool saved_specification_expr = specification_expr;
-      bool saved_formal_arg_flag = formal_arg_flag;
-
-      specification_expr = true;
-      formal_arg_flag = true;
-      gfc_resolve_array_spec (sym->result->as, false);
-      formal_arg_flag = saved_formal_arg_flag;
-      specification_expr = saved_specification_expr;
-    }
+    resolve_symbol_array_spec (sym->result, false);
 
   /* For a CLASS-valued function with a result variable, affirm that it has
      been resolved also when looking at the symbol 'sym'.  */
@@ -16723,18 +16727,7 @@  resolve_symbol (gfc_symbol *sym)
 
   check_constant = sym->attr.in_common && !sym->attr.pointer && !sym->error;
 
-  /* Set the formal_arg_flag so that check_conflict will not throw
-     an error for host associated variables in the specification
-     expression for an array_valued function.  */
-  if ((sym->attr.function || sym->attr.result) && sym->as)
-    formal_arg_flag = true;
-
-  saved_specification_expr = specification_expr;
-  specification_expr = true;
-  gfc_resolve_array_spec (sym->as, check_constant);
-  specification_expr = saved_specification_expr;
-
-  formal_arg_flag = false;
+  resolve_symbol_array_spec (sym, check_constant);
 
   /* Resolve formal namespaces.  */
   if (sym->formal_ns && sym->formal_ns != gfc_current_ns
diff --git a/gcc/fortran/symbol.cc b/gcc/fortran/symbol.cc
index 5d9852c79e0..2e50a2547eb 100644
--- a/gcc/fortran/symbol.cc
+++ b/gcc/fortran/symbol.cc
@@ -5334,3 +5334,61 @@  gfc_sym_get_dummy_args (gfc_symbol *sym)
 
   return dummies;
 }
+
+
+/* Given a procedure, returns the associated namespace.
+   The resulting NS should match the condition NS->PROC_NAME == SYM.  */
+
+gfc_namespace *
+gfc_get_procedure_ns (gfc_symbol *sym)
+{
+  if (sym->formal_ns
+      && sym->formal_ns->proc_name == sym)
+    return sym->formal_ns;
+
+  /* The above should have worked in most cases.  If it hasn't, try some other
+     heuristics, eventually returning SYM->NS.  */
+  if (gfc_current_ns->proc_name == sym)
+    return gfc_current_ns;
+
+  /* For contained procedures, the symbol's NS field is the
+     hosting namespace, not the procedure namespace.  */
+  if (sym->attr.flavor == FL_PROCEDURE && sym->attr.contained)
+    for (gfc_namespace *ns = sym->ns->contained; ns; ns = ns->sibling)
+      if (ns->proc_name == sym)
+	return ns;
+
+  if (sym->formal)
+    for (gfc_formal_arglist *f = sym->formal; f != nullptr; f = f->next)
+      if (f->sym)
+	{
+	  gfc_namespace *ns = f->sym->ns;
+	  if (ns && ns->proc_name == sym)
+	    return ns;
+	}
+
+  return sym->ns;
+}
+
+
+/* Given a symbol, returns the namespace in which the symbol is specified.
+   In most cases, it is the namespace hosting the symbol.  This is the case
+   for variables.  For functions, however, it is the function namespace
+   itself.  This specification namespace is used to check conformance of
+   array spec bound expressions.  */
+
+gfc_namespace *
+gfc_get_spec_ns (gfc_symbol *sym)
+{
+  if (sym->attr.flavor == FL_PROCEDURE
+      && sym->attr.function)
+    {
+      if (sym->result == sym)
+	return gfc_get_procedure_ns (sym);
+      /* Generic and intrinsic functions can have a null result.  */ 
+      else if (sym->result != nullptr)
+	return sym->result->ns;
+    }
+
+  return sym->ns;
+}
diff --git a/gcc/testsuite/gfortran.dg/spec_expr_8.f90 b/gcc/testsuite/gfortran.dg/spec_expr_8.f90
new file mode 100644
index 00000000000..5885810d421
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/spec_expr_8.f90
@@ -0,0 +1,24 @@ 
+! { dg-do compile }
+!
+! PR fortran/111781
+! We used to reject the example below because the dummy procedure g was
+! setting the current namespace without properly restoring it, which broke
+! the specification expression check for the dimension of A later on.
+!
+! Contributed by Markus Vikhamar-Sandberg  <rasmus.vikhamar-sandberg@uit.no>
+
+program example
+    implicit none
+    integer :: n
+    
+contains
+    
+    subroutine f(g,A)
+        real, intent(out) :: A(n)
+        interface
+          pure real(8) function g(x)
+            real(8), intent(in) :: x
+          end function
+        end interface
+    end subroutine
+end program
diff --git a/gcc/testsuite/gfortran.dg/spec_expr_9.f90 b/gcc/testsuite/gfortran.dg/spec_expr_9.f90
new file mode 100644
index 00000000000..9024909b4e9
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/spec_expr_9.f90
@@ -0,0 +1,19 @@ 
+! { dg-do compile }
+!
+! PR fortran/111781
+! Used to fail with Error: Variable ‘n’ cannot appear in the
+! expression at (1) for line 16.
+!
+program is_it_valid
+  dimension y(3)
+  integer :: n = 3
+  interface
+    function func(x)
+      import
+      dimension func(n)
+    end function
+  end interface
+  y=func(1.0)
+  print *, y
+  stop
+end