[gcc r10-10350] Fortran: improve checking of array specifications

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

https://gcc.gnu.org/g:e301a0a8a0f6287ff04e74893265e40dff256301

commit r10-10350-ge301a0a8a0f6287ff04e74893265e40dff256301
Author: Harald Anlauf <anlauf@gmx.de>
Date:   Thu Dec 2 22:33:49 2021 +0100

    Fortran: improve checking of array specifications
    
    gcc/fortran/ChangeLog:
    
            PR fortran/103505
            * array.c (match_array_element_spec): Try to simplify array
            element specifications to improve early checking.
            * expr.c (gfc_try_simplify_expr): New.  Try simplification of an
            expression via gfc_simplify_expr.  When an error occurs, roll
            back.
            * gfortran.h (gfc_try_simplify_expr): Declare it.
    
    gcc/testsuite/ChangeLog:
    
            PR fortran/103505
            * gfortran.dg/pr103505.f90: New test.
    
    Co-authored-by: Steven G. Kargl <kargl@gcc.gnu.org>
    (cherry picked from commit f46d32dd29b7623915e31b0508e2e925526fa7d8)

Diff:
---
 gcc/fortran/array.c                    |  4 ++++
 gcc/fortran/expr.c                     | 25 +++++++++++++++++++++++++
 gcc/fortran/gfortran.h                 |  1 +
 gcc/testsuite/gfortran.dg/pr103505.f90 |  9 +++++++++
 4 files changed, 39 insertions(+)

diff --git a/gcc/fortran/array.c b/gcc/fortran/array.c
index 8e4782ac1ae..5f3aec78711 100644
--- a/gcc/fortran/array.c
+++ b/gcc/fortran/array.c
@@ -492,6 +492,8 @@ match_array_element_spec (gfc_array_spec *as)
   if (!gfc_expr_check_typed (*upper, gfc_current_ns, false))
     return AS_UNKNOWN;
 
+  gfc_try_simplify_expr (*upper, 0);
+
   if (((*upper)->expr_type == EXPR_CONSTANT
 	&& (*upper)->ts.type != BT_INTEGER) ||
       ((*upper)->expr_type == EXPR_FUNCTION
@@ -524,6 +526,8 @@ match_array_element_spec (gfc_array_spec *as)
   if (!gfc_expr_check_typed (*upper, gfc_current_ns, false))
     return AS_UNKNOWN;
 
+  gfc_try_simplify_expr (*upper, 0);
+
   if (((*upper)->expr_type == EXPR_CONSTANT
 	&& (*upper)->ts.type != BT_INTEGER) ||
       ((*upper)->expr_type == EXPR_FUNCTION
diff --git a/gcc/fortran/expr.c b/gcc/fortran/expr.c
index 9c091fe74e1..9f5e84cbb1c 100644
--- a/gcc/fortran/expr.c
+++ b/gcc/fortran/expr.c
@@ -2328,6 +2328,31 @@ gfc_simplify_expr (gfc_expr *p, int type)
 }
 
 
+/* Try simplification of an expression via gfc_simplify_expr.
+   When an error occurs (arithmetic or otherwise), roll back.  */
+
+bool
+gfc_try_simplify_expr (gfc_expr *e, int type)
+{
+  gfc_expr *n;
+  bool t, saved_div0;
+
+  if (e == NULL || e->expr_type == EXPR_CONSTANT)
+    return true;
+
+  saved_div0 = gfc_seen_div0;
+  gfc_seen_div0 = false;
+  n = gfc_copy_expr (e);
+  t = gfc_simplify_expr (n, type) && !gfc_seen_div0;
+  if (t)
+    gfc_replace_expr (e, n);
+  else
+    gfc_free_expr (n);
+  gfc_seen_div0 = saved_div0;
+  return t;
+}
+
+
 /* Returns the type of an expression with the exception that iterator
    variables are automatically integers no matter what else they may
    be declared as.  */
diff --git a/gcc/fortran/gfortran.h b/gcc/fortran/gfortran.h
index e4bb8b8591f..2a669a37708 100644
--- a/gcc/fortran/gfortran.h
+++ b/gcc/fortran/gfortran.h
@@ -3307,6 +3307,7 @@ void gfc_free_ref_list (gfc_ref *);
 void gfc_type_convert_binary (gfc_expr *, int);
 bool gfc_is_constant_expr (gfc_expr *);
 bool gfc_simplify_expr (gfc_expr *, int);
+bool gfc_try_simplify_expr (gfc_expr *, int);
 int gfc_has_vector_index (gfc_expr *);
 
 gfc_expr *gfc_get_expr (void);
diff --git a/gcc/testsuite/gfortran.dg/pr103505.f90 b/gcc/testsuite/gfortran.dg/pr103505.f90
new file mode 100644
index 00000000000..522e53efcb2
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/pr103505.f90
@@ -0,0 +1,9 @@
+! { dg-do compile }
+! PR fortran/103505 - this used to ICE in compare_bound_mpz_t
+! Testcase by G.Steinmetz
+
+program p
+  integer, parameter :: a((2.))   = [4,8] ! { dg-error "scalar INTEGER" }
+  integer, parameter :: z(1:(2.)) = [4,8] ! { dg-error "scalar INTEGER" }
+  print *, a(1:1)                         ! { dg-error "Syntax error" }
+end