[gcc r12-5322] Fortran: avoid NULL pointer dereference on invalid range in logical SELECT CASE

[gcc r12-5322] Fortran: avoid NULL pointer dereference on invalid range in logical SELECT CASE

[Harald Anlauf]

https://gcc.gnu.org/g:3b3c9932338650c9a402cf1bfbdf7dfc03e185e7

commit r12-5322-g3b3c9932338650c9a402cf1bfbdf7dfc03e185e7
Author: Harald Anlauf <anlauf@gmx.de>
Date:   Tue Nov 16 21:06:06 2021 +0100

    Fortran: avoid NULL pointer dereference on invalid range in logical SELECT CASE
    
    gcc/fortran/ChangeLog:
    
            PR fortran/103286
            * resolve.c (resolve_select): Choose appropriate range limit to
            avoid NULL pointer dereference when generating error message.
    
    gcc/testsuite/ChangeLog:
    
            PR fortran/103286
            * gfortran.dg/pr103286.f90: New test.

Diff:
---
 gcc/fortran/resolve.c                  |  3 ++-
 gcc/testsuite/gfortran.dg/pr103286.f90 | 11 +++++++++++
 2 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/gcc/fortran/resolve.c b/gcc/fortran/resolve.c
index 705d2326a29..f074a0ab3a1 100644
--- a/gcc/fortran/resolve.c
+++ b/gcc/fortran/resolve.c
@@ -8846,7 +8846,8 @@ resolve_select (gfc_code *code, bool select_type)
 		  || cp->low != cp->high))
 	    {
 	      gfc_error ("Logical range in CASE statement at %L is not "
-			 "allowed", &cp->low->where);
+			 "allowed",
+			 cp->low ? &cp->low->where : &cp->high->where);
 	      t = false;
 	      break;
 	    }
diff --git a/gcc/testsuite/gfortran.dg/pr103286.f90 b/gcc/testsuite/gfortran.dg/pr103286.f90
new file mode 100644
index 00000000000..1c18b7136ce
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/pr103286.f90
@@ -0,0 +1,11 @@
+! { dg-do compile }
+! { dg-options "std=gnu" }
+! PR fortran/103286 - ICE in resolve_select
+
+program p
+  select case (.true.) ! { dg-warning "Extension: Conversion" }
+  case (1_8)
+  case (:0)            ! { dg-error "Logical range in CASE statement" }
+  case (2:)            ! { dg-error "Logical range in CASE statement" }
+  end select
+end