commit 45190d9eb5123df77bd60a1d6712f05a3af5f42c
Author: Sandra Loosemore <sandra@codesourcery.com>
Date:   Thu Jul 15 16:51:55 2021 -0700

    Bind(c): signed char is not a Fortran character type
    
    CFI_allocate and CFI_select_part were incorrectly treating
    CFI_type_signed_char as a Fortran character type for the purpose of
    deciding whether or not to use the elem_len argument.  It is a Fortran
    integer type per table 18.2 in the 2018 Fortran standard.
    
    Other functions in ISO_Fortran_binding.c appeared to handle this case
    correctly already.
    
    2021-07-15  Sandra Loosemore  <sandra@codesourcery.com>
    
    gcc/testsuite/
    	* gfortran.dg/ts29113/library/allocate-c.c (ctest): Also test
    	handling of elem_len for CFI_type_char vs CFI_type_signed_char.
    	* gfortran.dg/ts29113/library/select-c.c (ctest): Likewise.
    
    libgfortran/
    	* runtime/ISO_Fortran_binding.c (CFI_allocate)

diff --git a/gcc/testsuite/gfortran.dg/ts29113/library/allocate-c.c b/gcc/testsuite/gfortran.dg/ts29113/library/allocate-c.c
index 0208e5a..6343d28 100644
--- a/gcc/testsuite/gfortran.dg/ts29113/library/allocate-c.c
+++ b/gcc/testsuite/gfortran.dg/ts29113/library/allocate-c.c
@@ -135,5 +135,34 @@ ctest (void)
 		    CFI_deallocate (dv));
   if (dv->base_addr != NULL)
     abort ();
+
+  /* Signed char is not a Fortran character type.  Here we expect it to
+     ignore the elem_len argument and use the size of the type.  */
+  ex[0] = 3;
+  ex[1] = 4;
+  ex[2] = 5;
+  check_CFI_status ("CFI_establish",
+		    CFI_establish (dv, NULL, CFI_attribute_allocatable,
+				   CFI_type_signed_char, 4, 3, ex));
+  lb[0] = 1;
+  lb[1] = 2;
+  lb[2] = 3;
+  ub[0] = 10;
+  ub[1] = 5;
+  ub[2] = 10;
+  sm = sizeof (double);
+  check_CFI_status ("CFI_allocate",
+		    CFI_allocate (dv, lb, ub, sm));
+  dump_CFI_cdesc_t (dv);
+  if (dv->base_addr == NULL)
+    abort ();
+  if (dv->elem_len != sizeof (signed char))
+    abort ();
+
+  check_CFI_status ("CFI_deallocate",
+		    CFI_deallocate (dv));
+  if (dv->base_addr != NULL)
+    abort ();
+
 }
 
diff --git a/gcc/testsuite/gfortran.dg/ts29113/library/select-c.c b/gcc/testsuite/gfortran.dg/ts29113/library/select-c.c
index df6172c..9bcbc01 100644
--- a/gcc/testsuite/gfortran.dg/ts29113/library/select-c.c
+++ b/gcc/testsuite/gfortran.dg/ts29113/library/select-c.c
@@ -8,6 +8,8 @@
 
 /* Declare some source arrays.  */
 struct ss {
+  char c[4];
+  signed char b[4];
   int i, j, k;
 } s[10][5][3];
 
@@ -61,6 +63,31 @@ ctest (void)
   if (result->dim[2].sm != source->dim[2].sm)
     abort ();
 
+  /* Check that we use the given elem_size for char but not for
+     signed char, which is considered an integer type instead of a Fortran
+     character type.  */
+  check_CFI_status ("CFI_establish", 
+		    CFI_establish (result, NULL, CFI_attribute_pointer,
+				   CFI_type_char, 4, 3, NULL));
+  if (result->elem_len != 4)
+    abort ();
+  offset = offsetof (struct ss, c);
+  check_CFI_status ("CFI_select_part",
+		    CFI_select_part (result, source, offset, 4));
+  if (result->elem_len != 4)
+    abort ();
+
+  check_CFI_status ("CFI_establish", 
+		    CFI_establish (result, NULL, CFI_attribute_pointer,
+				   CFI_type_signed_char, 4, 3, NULL));
+  if (result->elem_len != sizeof (signed char))
+    abort ();
+  offset = offsetof (struct ss, c);
+  check_CFI_status ("CFI_select_part",
+		    CFI_select_part (result, source, offset, 4));
+  if (result->elem_len != sizeof (signed char))
+    abort ();
+
   /* Extract an array of character substrings.  */
   offset = 2;
   check_CFI_status ("CFI_establish",
diff --git a/libgfortran/runtime/ISO_Fortran_binding.c b/libgfortran/runtime/ISO_Fortran_binding.c
index 78953d0..9fe3a85 100644
--- a/libgfortran/runtime/ISO_Fortran_binding.c
+++ b/libgfortran/runtime/ISO_Fortran_binding.c
@@ -229,10 +229,9 @@ CFI_allocate (CFI_cdesc_t *dv, const CFI_index_t lower_bounds[],
 	}
     }
 
-  /* If the type is a character, the descriptor's element length is replaced
-     by the elem_len argument. */
-  if (dv->type == CFI_type_char || dv->type == CFI_type_ucs4_char ||
-      dv->type == CFI_type_signed_char)
+  /* If the type is a Fortran character type, the descriptor's element
+     length is replaced by the elem_len argument. */
+  if (dv->type == CFI_type_char || dv->type == CFI_type_ucs4_char)
     dv->elem_len = elem_len;
 
   /* Dimension information and calculating the array length. */
@@ -759,9 +758,9 @@ int CFI_select_part (CFI_cdesc_t *result, const CFI_cdesc_t *source,
 	}
     }
 
-  /* Element length. */
-  if (result->type == CFI_type_char || result->type == CFI_type_ucs4_char ||
-      result->type == CFI_type_signed_char)
+  /* Element length is ignored unless result->type specifies a Fortran
+     character type.  */
+  if (result->type == CFI_type_char || result->type == CFI_type_ucs4_char)
     result->elem_len = elem_len;
 
   if (unlikely (compile_options.bounds_check))