[gcc r13-4595] Fortran: reject bad SIZE argument while simplifying ISHFTC [PR106911]

[Harald Anlauf <anlauf@gcc.gnu.org>]

https://gcc.gnu.org/g:ae4438537fbc2ed04f3b0fb32d4e02b0ed6977a1

commit r13-4595-gae4438537fbc2ed04f3b0fb32d4e02b0ed6977a1
Author: Harald Anlauf <anlauf@gmx.de>
Date:   Sat Dec 10 22:05:15 2022 +0100

    Fortran: reject bad SIZE argument while simplifying ISHFTC [PR106911]
    
    gcc/fortran/ChangeLog:
    
            PR fortran/106911
            * simplify.cc (gfc_simplify_ishftc): If the SIZE argument is known
            to be outside the allowed range, terminate simplification.
    
    gcc/testsuite/ChangeLog:
    
            PR fortran/106911
            * gfortran.dg/pr106911.f90: New test.

Diff:
---
 gcc/fortran/simplify.cc                |  3 +++
 gcc/testsuite/gfortran.dg/pr106911.f90 | 18 ++++++++++++++++++
 2 files changed, 21 insertions(+)

diff --git a/gcc/fortran/simplify.cc b/gcc/fortran/simplify.cc
index aff9a1b8ced..3d3aaba84df 100644
--- a/gcc/fortran/simplify.cc
+++ b/gcc/fortran/simplify.cc
@@ -3955,6 +3955,9 @@ gfc_simplify_ishftc (gfc_expr *e, gfc_expr *s, gfc_expr *sz)
 	return NULL;
 
       gfc_extract_int (sz, &ssize);
+
+      if (ssize > isize || ssize <= 0)
+	return &gfc_bad_expr;
     }
   else
     ssize = isize;
diff --git a/gcc/testsuite/gfortran.dg/pr106911.f90 b/gcc/testsuite/gfortran.dg/pr106911.f90
new file mode 100644
index 00000000000..f3fe7f6ad68
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/pr106911.f90
@@ -0,0 +1,18 @@
+! { dg-do compile }
+! PR fortran/106911 - ICE in gfc_convert_mpz_to_signed
+! Contributed by G.Steinmetz
+
+program p
+  implicit none
+  integer, parameter :: a = 10
+  integer, parameter :: b = 20
+  integer, parameter :: c = ishftc(1_1, a, b) ! { dg-error "must be less than or equal" }
+  integer, parameter :: d = ishftc(1_1, a, 0) ! { dg-error "must be positive" }
+  interface
+     subroutine s
+       import :: a, b
+       integer, parameter :: e = ishftc(1_1, a, b) ! { dg-error "must be less than or equal" }
+       integer, parameter :: f = ishftc(1_1, a, 0) ! { dg-error "must be positive" }
+     end
+  end interface
+end