From de9375b4d98033acdc22623194605cd9c4dbdb02 Mon Sep 17 00:00:00 2001
From: Alexis Mousset <alexis.mousset@rudder.io>
Date: Mon, 9 Feb 2026 20:32:52 +0100
Subject: [PATCH 1/2] Make expandrange able to output a single value

- Allow ranges with a unique value (as the range is already inclusive)
- Make invalid step value a soft fail

Changelog: Allow expandrange to output a single value
---
 libpromises/evalfunction.c                    |  6 ++-
 .../01_vars/02_functions/expand_range.cf      | 43 +++++++++++++++++++
 2 files changed, 47 insertions(+), 2 deletions(-)
 create mode 100644 tests/acceptance/01_vars/02_functions/expand_range.cf

diff --git a/libpromises/evalfunction.c b/libpromises/evalfunction.c
index 1e6da00223..52f9d1b430 100644
--- a/libpromises/evalfunction.c
+++ b/libpromises/evalfunction.c
@@ -4558,9 +4558,11 @@ static FnCallResult FnCallExpandRange(EvalContext *ctx, ARG_UNUSED const Policy
         sscanf(template, "%[^[\[][%d-%d]%[^\n]", before, &from, &to, after);
     }
 
-    if (step_size < 1 || abs(from-to) < step_size)
+    if (step_size < 1)
     {
-        FatalError(ctx, "EXPANDRANGE Step size cannot be less than 1 or greater than the interval");
+        assert(fp->name != NULL);
+        Log(LOG_LEVEL_ERR, "%s: Step size cannot be less than 1", fp->name);
+        return FnFailure();
     }
 
     if (from == CF_NOINT || to == CF_NOINT)
diff --git a/tests/acceptance/01_vars/02_functions/expand_range.cf b/tests/acceptance/01_vars/02_functions/expand_range.cf
new file mode 100644
index 0000000000..8d955478c9
--- /dev/null
+++ b/tests/acceptance/01_vars/02_functions/expand_range.cf
@@ -0,0 +1,43 @@
+# data_regextract() test
+
+body common control
+{
+      inputs => { "../../default.cf.sub" };
+      bundlesequence => { default("$(this.promise_filename)") };
+}
+
+bundle agent test
+{
+  vars:
+    "case1"  slist  => expandrange("case1[1-3]", 1);
+    "case1s" string => format("%S", "case1");
+    "case2"  slist  => expandrange("case2[1-10]", 3);
+    "case2s" string => format("%S", "case2");
+    "case3"  slist  => expandrange("case3[1-1]", 3);
+    "case3s" string => format("%S", "case3");
+    "case4"  slist  => expandrange("case4[1-2]", 3);
+    "case4s" string => format("%S", "case4");
+}
+
+bundle agent check
+{
+  vars:
+      "actual" string => "
+1 $(test.case1s)
+2 $(test.case2s)
+3 $(test.case3s)
+4 $(test.case4s)
+";
+
+      "expected" string => '
+1 { \"case11\", \"case12\", \"case13\" }
+2 { \"case21\", \"case24\", \"case27\", \"case210\" }
+3 { \"case31\" }
+4 { \"case41\" }
+';
+
+  methods:
+      "" usebundle => dcs_check_strcmp($(actual), $(expected),
+                                      $(this.promise_filename),
+                                      "no");
+}

From f1c21c6c6af3be44cf4fbc985940ec2e9d35cdfb Mon Sep 17 00:00:00 2001
From: Alexis Mousset <alexis.mousset@rudder.io>
Date: Wed, 11 Feb 2026 00:58:11 +0100
Subject: [PATCH 2/2] Fix assert

---
 libpromises/evalfunction.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/libpromises/evalfunction.c b/libpromises/evalfunction.c
index 52f9d1b430..97bf208549 100644
--- a/libpromises/evalfunction.c
+++ b/libpromises/evalfunction.c
@@ -4539,6 +4539,8 @@ static FnCallResult FnCallMapList(EvalContext *ctx,
 
 static FnCallResult FnCallExpandRange(EvalContext *ctx, ARG_UNUSED const Policy *policy, ARG_UNUSED const FnCall *fp, const Rlist *finalargs)
 {
+    assert(fp != NULL);
+
     Rlist *newlist = NULL;
     const char *template = RlistScalarValue(finalargs);
     char *step = RlistScalarValue(finalargs->next);
@@ -4560,7 +4562,6 @@ static FnCallResult FnCallExpandRange(EvalContext *ctx, ARG_UNUSED const Policy
 
     if (step_size < 1)
     {
-        assert(fp->name != NULL);
         Log(LOG_LEVEL_ERR, "%s: Step size cannot be less than 1", fp->name);
         return FnFailure();
     }