[PATCH v3 1/8] gdb support: add gdb::ranges::replace algorithm

[Matthieu Longo <matthieu.longo@arm.com>]

Provide a C++17-compatible replacement for the C++20 std::ranges::replace
algorithm, allowing callers to use a consistent interface until GDB
transitions to C++20. The helper should be removed once the C++ standard
library implementation become available.

Also add unit tests for ranges::replace.

https://en.cppreference.com/cpp/algorithm/ranges/replace
---
 gdb/Makefile.in                  |  1 +
 gdb/unittests/ranges-selftests.c | 63 ++++++++++++++++++++++++++++++++
 gdbsupport/ranges.h              | 39 ++++++++++++++++++++
 3 files changed, 103 insertions(+)
 create mode 100644 gdb/unittests/ranges-selftests.c
 create mode 100644 gdbsupport/ranges.h

diff --git a/gdb/Makefile.in b/gdb/Makefile.in
index d1574ec2d2c..9d34b6cd3e4 100644
--- a/gdb/Makefile.in
+++ b/gdb/Makefile.in
@@ -483,6 +483,7 @@ SELFTESTS_SRCS = \
 	unittests/ptid-selftests.c \
 	unittests/main-thread-selftests.c \
 	unittests/mkdir-recursive-selftests.c \
+	unittests/ranges-selftests.c \
 	unittests/remote-arg-selftests.c \
 	unittests/rsp-low-selftests.c \
 	unittests/scoped_fd-selftests.c \
diff --git a/gdb/unittests/ranges-selftests.c b/gdb/unittests/ranges-selftests.c
new file mode 100644
index 00000000000..6791502cc1f
--- /dev/null
+++ b/gdb/unittests/ranges-selftests.c
@@ -0,0 +1,63 @@
+/* Self tests for gdb::ranges algorithms for GDB, the GNU debugger.
+
+   Copyright (C) 2017-2026 Free Software Foundation, Inc.
+
+   This file is part of GDB.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+#include "gdbsupport/selftest.h"
+#include "gdbsupport/array-view.h"
+#include "gdbsupport/ranges.h"
+#include <array>
+#include <vector>
+
+namespace selftests {
+namespace ranges_replace_tests {
+
+/* Entry point.  */
+
+static void
+run_tests ()
+{
+  /* With owning container, no copy and elements correctly replaced.  */
+  {
+    std::vector<int> vec = {1, 2, 3, 2};
+    gdb::ranges::replace (vec, 2, 1);
+    SELF_CHECK (vec[0] == 1);
+    SELF_CHECK (vec[1] == 1);
+    SELF_CHECK (vec[2] == 3);
+    SELF_CHECK (vec[3] == 1);
+  }
+
+  /* With non-owning container.  */
+  {
+    std::array<int, 4> array = {1, 2, 3, 2};
+    gdb::array_view<int> view = array;
+    gdb::ranges::replace (view, 2, 1);
+    SELF_CHECK (array[0] == 1);
+    SELF_CHECK (array[1] == 1);
+    SELF_CHECK (array[2] == 3);
+    SELF_CHECK (array[3] == 1);
+  }
+}
+
+} /* namespace ranges_replaceq_tests */
+} /* namespace selftests */
+
+INIT_GDB_FILE (ranges_selftests)
+{
+  selftests::register_test ("ranges_replace",
+			    selftests::ranges_replace_tests::run_tests);
+}
diff --git a/gdbsupport/ranges.h b/gdbsupport/ranges.h
new file mode 100644
index 00000000000..96d9c0162bb
--- /dev/null
+++ b/gdbsupport/ranges.h
@@ -0,0 +1,39 @@
+/* Copyright (C) 2026 Free Software Foundation, Inc.
+
+   This file is part of GDB.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+#ifndef GDBSUPPORT_RANGES_H
+#define GDBSUPPORT_RANGES_H
+
+namespace gdb {
+namespace ranges {
+
+/* Replace all occurrences of a value in the provided range.
+
+   Note: this helper is a reimplementation of std::ranges::replace, only
+   available from C++20 onwards, and consequently, should be replaced by
+   std::ranges::replace once GDB switches to C++20.  */
+
+template <class Range, typename T>
+void replace (Range &&r, const T &old_value, const T &new_value)
+{
+  std::replace (r.begin (), r.end (), old_value, new_value);
+}
+
+} /* namespace ranges */
+} /* namespace gdb */
+
+#endif /* GDBSUPPORT_RANGES_H */
-- 
2.55.0