Take care of some corner-cases of non-const tracking.

tests/test.cmp

@@ -24813,6 +24813,7 @@ TRANSLATE "Executing `%s' for INCLUDECMD and caching as `%s'" ""
 TRANSLATE "Found cached directory listing for `%s'" ""
 TRANSLATE "Function `%s' defined at %s(%s) should take %d argument%s, but actually takes %d" ""
 TRANSLATE "Function `%s' redefined: previously defined at %s(%s)" ""
+TRANSLATE "Function definition considered non-constant because of context" ""
 TRANSLATE "GetValidHebDate: Bad adarbehave value %d" ""
 TRANSLATE "Global variable `%s' makes expression non-constant" ""
 TRANSLATE "In" ""
@@ -24841,6 +24842,7 @@ TRANSLATE "System variable `$%s' makes expression non-constant" ""
 TRANSLATE "Undefined %s function: `%s'" ""
 TRANSLATE "Unmatched PUSH-OMIT-CONTEXT at %s(%d)" ""
 TRANSLATE "Unrecognized command; interpreting as REM" ""
+TRANSLATE "User function `%s' defined in non-constant context makes expression non-constant" ""
 TRANSLATE "Variable assignment considered non-constant because of context" ""
 TRANSLATE "Warning: Function name `%s...' truncated to `%s'" ""
 TRANSLATE "Warning: OMIT is ignored if you use OMITFUNC" ""

tests/test.rem

@@ -1532,6 +1532,32 @@ REM SCANFROM -7 MSG foo
 
 REM MSG [g(3)]
 
+# Check user-functions for constant-ness
+FUNSET f
+IF today() > '1990-01-01'
+    FSET f(x) 2
+ELSE
+    FSET f(x) 3
+ENDIF
+
+SET a f(1)
+
+FUNSET f
+FSET f(x) '1990-01-01'
+IF today() < '1990-01-01'
+    FSET f(x) '2025-12-31'
+ENDIF
+
+set a f(1)
+FUNSET F
+
+SET a 1
+IF today() < '1990-01-01'
+    SET a 2
+ENDIF
+
+dump -c a
+
 DEBUG -n
 
 DEBUG -e