From 43c0185764ec878576ef2255d9df24fbb1961af4 Mon Sep 17 00:00:00 2001
From: Harald Anlauf <anlauf@gmx.de>
Date: Wed, 24 Jan 2024 22:28:31 +0100
Subject: [PATCH] Fortran: use name of array component in runtime error message
 [PR30802]

gcc/fortran/ChangeLog:

	PR fortran/30802
	* trans-array.cc (trans_array_bound_check): Derive name of component
	for use in runtime error message.

gcc/testsuite/ChangeLog:

	PR fortran/30802
	* gfortran.dg/bounds_check_fail_8.f90: New test.
---
 gcc/fortran/trans-array.cc                    | 34 ++++++++++++++++++
 .../gfortran.dg/bounds_check_fail_8.f90       | 35 +++++++++++++++++++
 2 files changed, 69 insertions(+)
 create mode 100644 gcc/testsuite/gfortran.dg/bounds_check_fail_8.f90

diff --git a/gcc/fortran/trans-array.cc b/gcc/fortran/trans-array.cc
index 878a92aff18..f6ddce2d023 100644
--- a/gcc/fortran/trans-array.cc
+++ b/gcc/fortran/trans-array.cc
@@ -3497,6 +3497,10 @@ trans_array_bound_check (gfc_se * se, gfc_ss *ss, tree index, int n,
   tree descriptor;
   char *msg;
   const char * name = NULL;
+  char *var_name = NULL;
+  gfc_expr *expr;
+  gfc_ref *ref;
+  size_t len;

   if (!(gfc_option.rtcheck & GFC_RTCHECK_BOUNDS))
     return index;
@@ -3509,6 +3513,36 @@ trans_array_bound_check (gfc_se * se, gfc_ss *ss, tree index, int n,
   name = ss->info->expr->symtree->n.sym->name;
   gcc_assert (name != NULL);

+  /* When we have a component ref, compile name for the array section.
+     Note that there can only be one part ref.  */
+  expr = ss->info->expr;
+  if (expr->ref && !compname)
+    {
+      len = strlen (name) + 1;
+
+      /* Find a safe length.  */
+      for (ref = expr->ref; ref; ref = ref->next)
+	if (ref->type == REF_COMPONENT)
+	  len += 2 + strlen (ref->u.c.component->name);
+
+      var_name = XALLOCAVEC (char, len);
+      strcpy (var_name, name);
+
+      for (ref = expr->ref; ref; ref = ref->next)
+	{
+	  /* Append component name.  */
+	  if (ref->type == REF_COMPONENT)
+	    {
+	      strcat (var_name, "%%");
+	      strcat (var_name, ref->u.c.component->name);
+	      continue;
+	    }
+	  if (ref->type == REF_ARRAY && ref->u.ar.type == AR_SECTION)
+	    break;
+	}
+      name = var_name;
+    }
+
   if (VAR_P (descriptor))
     name = IDENTIFIER_POINTER (DECL_NAME (descriptor));

diff --git a/gcc/testsuite/gfortran.dg/bounds_check_fail_8.f90 b/gcc/testsuite/gfortran.dg/bounds_check_fail_8.f90
new file mode 100644
index 00000000000..3397e953ba6
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/bounds_check_fail_8.f90
@@ -0,0 +1,35 @@
+! { dg-do compile }
+! { dg-additional-options "-fcheck=bounds -g -fdump-tree-original" }
+! { dg-output "At line 22 .*" }
+! { dg-shouldfail "dimension 3 of array 'uu%z' outside of expected range" }
+!
+! PR fortran/30802 - improve bounds-checking for array references
+!
+! Checking the proper component references is the most important part here.
+
+program test
+  implicit none
+  integer :: k = 0
+  type t
+     real, dimension(10,20,30) :: z = 23
+  end type t
+  type u
+     type(t) :: vv(4,5)
+  end type u
+  type(t) :: uu,     ww(1)
+  type(u) :: x1, x2, y1(1), y2(1)
+
+  print *, uu   % z(1,k,:)           ! runtime check only for dimension 2 of z
+  print *, ww(1)% z(1,:,k)           ! runtime check only for dimension 3 of z
+  print *, x1   % vv(2,3)% z(1,:,k)  ! runtime check only for dimension 3 of z
+  print *, x2   % vv(k,:)% z(1,2,3)  ! runtime check only for dimension 1 of vv
+  print *, y1(1)% vv(2,3)% z(1,:,k)  ! runtime check only for dimension 3 of z
+  print *, y2(1)% vv(:,k)% z(1,2,3)  ! runtime check only for dimension 2 of vv
+end program test
+
+! { dg-final { scan-tree-dump-times "'uu%%z.' outside of expected range" 2 "original" } }
+! { dg-final { scan-tree-dump-times "'ww%%z.' outside of expected range" 2 "original" } }
+! { dg-final { scan-tree-dump-times "'x1%%vv%%z.' outside of expected range" 2 "original" } }
+! { dg-final { scan-tree-dump-times "'x2%%vv.' outside of expected range" 2 "original" } }
+! { dg-final { scan-tree-dump-times "'y1%%vv%%z.' outside of expected range" 2 "original" } }
+! { dg-final { scan-tree-dump-times "'y2%%vv.' outside of expected range" 2 "original" } }
--
2.35.3