PR fortran/93340 - fix missed substring simplifications

Substrings were not reduced early enough for use in initializations,
such as DATA statements.  Add an early simplification for substrings
with constant starting and ending points.

gcc/fortran/ChangeLog:

	* gfortran.h (gfc_resolve_substring): Add prototype.
	* primary.c (match_string_constant): Simplify substrings with
	constant starting and ending points.
	* resolve.c: Rename resolve_substring to gfc_resolve_substring.
	(gfc_resolve_ref): Use renamed function gfc_resolve_substring.

gcc/testsuite/ChangeLog:

	* substr_10.f90: New test.
	* substr_9.f90: New test.

diff --git a/gcc/fortran/gfortran.h b/gcc/fortran/gfortran.h
index 6585e4f3ecd207a12e5c22340e75566fa33fe15e..4dd72b620c97631afb78acf076d665c48d4b65b0 100644 (file)
--- a/gcc/fortran/gfortran.h
+++ b/gcc/fortran/gfortran.h
@@ -3467,6 +3467,7 @@ bool find_forall_index (gfc_expr *, gfc_symbol *, int);
 bool gfc_resolve_index (gfc_expr *, int);
 bool gfc_resolve_dim_arg (gfc_expr *);
 bool gfc_is_formal_arg (void);
+bool gfc_resolve_substring (gfc_ref *, bool *);
 void gfc_resolve_substring_charlen (gfc_expr *);
 match gfc_iso_c_sub_interface(gfc_code *, gfc_symbol *);
 gfc_expr *gfc_expr_to_initialize (gfc_expr *);

diff --git a/gcc/fortran/primary.c b/gcc/fortran/primary.c
index db9ecf9a4f67370d67479a0531c3630346745928..d0610d02ebdc03ee9262eea325837375a8460217 100644 (file)
--- a/gcc/fortran/primary.c
+++ b/gcc/fortran/primary.c
@@ -1190,6 +1190,61 @@ got_delim:
   if (match_substring (NULL, 0, &e->ref, false) != MATCH_NO)
     e->expr_type = EXPR_SUBSTRING;
 
+  /* Substrings with constant starting and ending points are eligible as
+     designators (F2018, section 9.1).  Simplify substrings to make them usable
+     e.g. in data statements.  */
+  if (e->expr_type == EXPR_SUBSTRING
+      && e->ref && e->ref->type == REF_SUBSTRING
+      && e->ref->u.ss.start->expr_type == EXPR_CONSTANT
+      && (e->ref->u.ss.end == NULL
+         || e->ref->u.ss.end->expr_type == EXPR_CONSTANT))
+    {
+      gfc_expr *res;
+      ptrdiff_t istart, iend;
+      size_t length;
+      bool equal_length = false;
+
+      /* Basic checks on substring starting and ending indices.  */
+      if (!gfc_resolve_substring (e->ref, &equal_length))
+       return MATCH_ERROR;
+
+      length = e->value.character.length;
+      istart = gfc_mpz_get_hwi (e->ref->u.ss.start->value.integer);
+      if (e->ref->u.ss.end == NULL)
+       iend = length;
+      else
+       iend = gfc_mpz_get_hwi (e->ref->u.ss.end->value.integer);
+
+      if (istart <= iend)
+       {
+         if (istart < 1)
+           {
+             gfc_error ("Substring start index (%ld) at %L below 1",
+                        (long) istart, &e->ref->u.ss.start->where);
+             return MATCH_ERROR;
+           }
+         if (iend > (ssize_t) length)
+           {
+             gfc_error ("Substring end index (%ld) at %L exceeds string "
+                        "length", (long) iend, &e->ref->u.ss.end->where);
+             return MATCH_ERROR;
+           }
+         length = iend - istart + 1;
+       }
+      else
+       length = 0;
+
+      res = gfc_get_constant_expr (BT_CHARACTER, e->ts.kind, &e->where);
+      res->value.character.string = gfc_get_wide_string (length + 1);
+      res->value.character.length = length;
+      if (length > 0)
+       memcpy (res->value.character.string,
+               &e->value.character.string[istart - 1],
+               length * sizeof (gfc_char_t));
+      res->value.character.string[length] = '\0';
+      e = res;
+    }
+
   *result = e;
 
   return MATCH_YES;

diff --git a/gcc/fortran/resolve.c b/gcc/fortran/resolve.c
index ab7ffc2c8b64d741d53b06932a16167a01910dfa..bb069efef032be2328f02edcebbf363349e6f543 100644 (file)
--- a/gcc/fortran/resolve.c
+++ b/gcc/fortran/resolve.c
@@ -5068,8 +5068,8 @@ resolve_array_ref (gfc_array_ref *ar)
 }
 
 
-static bool
-resolve_substring (gfc_ref *ref, bool *equal_length)
+bool
+gfc_resolve_substring (gfc_ref *ref, bool *equal_length)
 {
   int k = gfc_validate_kind (BT_INTEGER, gfc_charlen_int_kind, false);
 
@@ -5277,7 +5277,7 @@ gfc_resolve_ref (gfc_expr *expr)
 
       case REF_SUBSTRING:
        equal_length = false;
-       if (!resolve_substring (*prev, &equal_length))
+       if (!gfc_resolve_substring (*prev, &equal_length))
          return false;
 
        if (expr->expr_type != EXPR_SUBSTRING && equal_length)

diff --git a/gcc/testsuite/substr_10.f90 b/gcc/testsuite/substr_10.f90
new file mode 100644 (file)
index 0000000..918ca8a
--- /dev/null
+++ b/gcc/testsuite/substr_10.f90
@@ -0,0 +1,11 @@
+! { dg-do compile }
+! PR93340 - test error handling of substring simplification
+
+subroutine p
+  integer,parameter :: k = len ('a'(:0))
+  integer,parameter :: m = len ('a'(0:)) ! { dg-error "Substring start index" }
+  call foo ('bcd'(-8:-9))
+  call foo ('bcd'(-9:-8)) ! { dg-error "Substring start index" }
+  call foo ('bcd'(:12))   ! { dg-error "Substring end index" }
+  call foo ('bcd'(-12:))  ! { dg-error "Substring start index" }
+end

diff --git a/gcc/testsuite/substr_9.f90 b/gcc/testsuite/substr_9.f90
new file mode 100644 (file)
index 0000000..73152d6
--- /dev/null
+++ b/gcc/testsuite/substr_9.f90
@@ -0,0 +1,28 @@
+! { dg-do run }
+! { dg-options "-std=gnu -fdump-tree-original" }
+! PR93340 - issues with substrings in initializers
+
+program p
+  implicit none
+  integer, parameter :: m = 1
+  character b(2) /'a', 'b'   (1:1)/
+  character c(2) /'a', 'bc'  (1:1)/
+  character d(2) /'a', 'bxyz'(m:m)/
+  character e(2)
+  character f(2)
+  data e /'a', 'bxyz'( :1)/
+  data f /'a', 'xyzb'(4:4)/
+  character :: g(2) = [ 'a', 'b' (1:1) ]
+  character :: h(2) = [ 'a', 'bc'(1:1) ]
+  character :: k(2) = [ 'a', 'bc'(m:1) ]
+  if (b(2) /= "b") stop 1
+  if (c(2) /= "b") stop 2
+  if (d(2) /= "b") stop 3
+  if (e(2) /= "b") stop 4
+  if (f(2) /= "b") stop 5
+  if (g(2) /= "b") stop 6
+  if (h(2) /= "b") stop 7
+  if (k(2) /= "b") stop 8
+end
+
+! { dg-final { scan-tree-dump-times "xyz" 0 "original" } }