Dear all,
when playing around with the issues exposed by PR93340, particularly visible
in the tree dump, I tried to find ways to simplify substrings in those cases
where they are eligible as designator, which is required e.g. in DATA
statements.
Given my limited understanding, I finally arrived at a potential solution which
does that simplification near the end of match_string_constant in primary.c.
I couldn't find a better place, but I am open to better suggestions.
The simplification below does an even better job at detecting invalid substring
starting or ending indices than HEAD, and regtests cleanly on
x86_64-pc-linux-gnu.
Feedback appreciated. Is this potentially ok for master, or should this be done
differently?
Thanks,
Harald
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 6585e4f3ecd..4dd72b620c9 100644
--- 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 db9ecf9a4f6..7cb378e3090 100644
--- 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 f243bd185b0..3929ddff849 100644
--- 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
index 00000000000..918ca8af162
--- /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
index 00000000000..73152d6627f
--- /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" } }
