CFE-4244: Add the function name to the result cache key

The function cache only used the args values, which in some cases
could lead to mixing results from different functions with the same arguments.

libpromises/eval_context.c

@@ -2837,7 +2837,14 @@ bool EvalContextFunctionCacheGet(const EvalContext *ctx,
         return false;
     }
 
-    Rval *rval = FuncCacheMapGet(ctx->function_cache, args);
+    // The cache key is made of the function name and all args values
+    Rlist *args_copy = RlistCopy(args);
+    assert(fp != NULL);
+    assert(fp->name != NULL);
+    assert(ctx != NULL);
+    Rlist *key = RlistPrepend(&args_copy, fp->name, RVAL_TYPE_SCALAR);
+    Rval *rval = FuncCacheMapGet(ctx->function_cache, key);
+    RlistDestroy(key);
     if (rval)
     {
         if (rval_out)
@@ -2863,7 +2870,14 @@ void EvalContextFunctionCachePut(EvalContext *ctx,
 
     Rval *rval_copy = xmalloc(sizeof(Rval));
     *rval_copy = RvalCopy(*rval);
-    FuncCacheMapInsert(ctx->function_cache, RlistCopy(args), rval_copy);
+
+    Rlist *args_copy = RlistCopy(args);
+    assert(fp != NULL);
+    assert(fp->name != NULL);
+    assert(ctx != NULL);
+    Rlist *key = RlistPrepend(&args_copy, fp->name, RVAL_TYPE_SCALAR);
+
+    FuncCacheMapInsert(ctx->function_cache, key, rval_copy);
 }
 
 /* cfPS and associated machinery */

tests/acceptance/01_vars/02_functions/cache_name.cf

@@ -0,0 +1,38 @@
+#######################################################
+#
+# Test that the function result cache checks function name
+#
+#######################################################
+
+body common control
+{
+      inputs => { "../../default.cf.sub" };
+      bundlesequence  => { default("$(this.promise_filename)") };
+      version => "1.0";
+}
+
+#######################################################
+
+
+bundle agent init
+{
+}
+
+#######################################################
+
+bundle agent test
+{
+  vars:
+    "res1" string => host2ip("cfengine.com");
+    # must not reuse result from previous line
+    "res2" string => ip2host("cfengine.com");
+}
+
+
+#######################################################
+
+bundle agent check
+{
+  methods:
+      "any" usebundle => dcs_check_strcmp("${test.res1}", "${test.res2}", "$(this.promise_filename)", "yes");
+}