From ebc8ed3246ff5949c2e4cf8af6726c5111ef381f Mon Sep 17 00:00:00 2001
From: Christopher Albert <albert@tugraz.at>
Date: Sat, 28 Mar 2026 16:57:02 +0100
Subject: [PATCH] fortran: Fix character SPREAD intrinsic lowering [PR109788]

Copy the SPREAD intrinsic descriptor before specializing the character
formal argument type so other uses keep the generic signature.

	PR fortran/109788

gcc/fortran/ChangeLog:

	* iresolve.cc (copy_intrinsic_sym): New helper.
	(gfc_resolve_spread): Copy the intrinsic descriptor before
	specializing the character formal argument type.

gcc/testsuite/ChangeLog:

	* gfortran.dg/pr109788.f90: New test.

Signed-off-by: Christopher Albert <albert@tugraz.at>
---
 gcc/fortran/iresolve.cc                | 25 ++++++++++++++++++++++++-
 gcc/testsuite/gfortran.dg/pr109788.f90 | 10 ++++++++++
 2 files changed, 34 insertions(+), 1 deletion(-)
 create mode 100644 gcc/testsuite/gfortran.dg/pr109788.f90

diff --git a/gcc/fortran/iresolve.cc b/gcc/fortran/iresolve.cc
index 833701da5df..7ec821baa9e 100644
--- a/gcc/fortran/iresolve.cc
+++ b/gcc/fortran/iresolve.cc
@@ -103,6 +103,25 @@ check_charlen_present (gfc_expr *source)
     }
 }
 
+static gfc_intrinsic_sym *
+copy_intrinsic_sym (const gfc_intrinsic_sym *src)
+{
+  gfc_intrinsic_sym *copy = XCNEW (gfc_intrinsic_sym);
+  gfc_intrinsic_arg *head = NULL;
+  gfc_intrinsic_arg **tail = &head;
+
+  *copy = *src;
+  for (const gfc_intrinsic_arg *arg = src->formal; arg; arg = arg->next)
+    {
+      *tail = XCNEW (gfc_intrinsic_arg);
+      **tail = *arg;
+      (*tail)->next = NULL;
+      tail = &(*tail)->next;
+    }
+  copy->formal = head;
+  return copy;
+}
+
 /* Helper function for resolving the "mask" argument.  */
 
 static void
@@ -2958,7 +2977,11 @@ gfc_resolve_spread (gfc_expr *f, gfc_expr *source, gfc_expr *dim,
     gfc_resolve_substring_charlen (source);
 
   if (source->ts.type == BT_CHARACTER)
-    check_charlen_present (source);
+    {
+      check_charlen_present (source);
+      f->value.function.isym = copy_intrinsic_sym (f->value.function.isym);
+      f->value.function.isym->formal->ts = source->ts;
+    }
 
   f->ts = source->ts;
   f->rank = source->rank + 1;
diff --git a/gcc/testsuite/gfortran.dg/pr109788.f90 b/gcc/testsuite/gfortran.dg/pr109788.f90
new file mode 100644
index 00000000000..d581b7a70fe
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/pr109788.f90
@@ -0,0 +1,10 @@
+! { dg-do compile }
+! { dg-options "-Os -fdump-tree-original-raw" }
+! { dg-final { scan-tree-dump {(?s)identifier_node  strg: _gfortran_spread_char_scalar.*?function_type.*?prms: @[0-9]+.*?tree_list[^\n]*chan: @[0-9]+.*?tree_list[^\n]*chan: @[0-9]+.*?tree_list[^\n]*chan: @[0-9]+.*?tree_list[^\n]*chan: @[0-9]+.*?tree_list[^\n]*chan: @[0-9]+.*?tree_list[^\n]*chan: @8} "original" } }
+
+character(3) :: a = 'abc'
+
+associate (y => spread(trim(a), 1, 2) // 'd')
+  if (size(y) /= 2) stop 1
+end associate
+end