Allow trailing commas in bare lists

This applies to macro arguments, DB, DW, DL, DS,
PRINT, PRINTLN, EXPORT, PURGE, and OPT.

It also removes support for empty entries in DB/DW/DL.
(Deprecating it would require keeping parser support,
which is ambiguous with trailing commas.)

Fixes #753

test/asm/macro-arguments.asm

@@ -9,15 +9,20 @@ ENDM
 
 	mac /* block
 		...comment */ ; comment
-	mac /*a*/ 1 , 2 /*b*/
+	mac /*a*/ 1 , 2 /*b*/ , ; trailing comma
 	mac \
 	c, d
 	mac 1, 2 + /* another ;
 		; comment */ 2, 3
 
+	mac           a                                                                                                                                                                                                                                                               b           ; truncated
+
 	mac
+	mac ,
+	mac a,
 	mac a,,
 	mac ,,z
 	mac a,,z
 	mac ,a,b,c,
-	mac ,,x,,
+	mac ,,x,,,
+	mac E,O,F ; no newline

test/asm/macro-arguments.err

@@ -1,22 +1,22 @@
-warning: macro-arguments.asm(19): [-Wempty-macro-arg]
-    Empty macro argument
-warning: macro-arguments.asm(19): [-Wempty-macro-arg]
-    Empty macro argument
-warning: macro-arguments.asm(20): [-Wempty-macro-arg]
-    Empty macro argument
-warning: macro-arguments.asm(20): [-Wempty-macro-arg]
-    Empty macro argument
+warning: macro-arguments.asm(18): [-Wlong-string]
+    Macro argument too long
 warning: macro-arguments.asm(21): [-Wempty-macro-arg]
     Empty macro argument
-warning: macro-arguments.asm(22): [-Wempty-macro-arg]
-    Empty macro argument
-warning: macro-arguments.asm(22): [-Wempty-macro-arg]
-    Empty macro argument
 warning: macro-arguments.asm(23): [-Wempty-macro-arg]
     Empty macro argument
-warning: macro-arguments.asm(23): [-Wempty-macro-arg]
+warning: macro-arguments.asm(24): [-Wempty-macro-arg]
     Empty macro argument
-warning: macro-arguments.asm(23): [-Wempty-macro-arg]
+warning: macro-arguments.asm(24): [-Wempty-macro-arg]
     Empty macro argument
-warning: macro-arguments.asm(23): [-Wempty-macro-arg]
+warning: macro-arguments.asm(25): [-Wempty-macro-arg]
+    Empty macro argument
+warning: macro-arguments.asm(26): [-Wempty-macro-arg]
+    Empty macro argument
+warning: macro-arguments.asm(27): [-Wempty-macro-arg]
+    Empty macro argument
+warning: macro-arguments.asm(27): [-Wempty-macro-arg]
+    Empty macro argument
+warning: macro-arguments.asm(27): [-Wempty-macro-arg]
+    Empty macro argument
+warning: macro-arguments.asm(27): [-Wempty-macro-arg]
     Empty macro argument

test/asm/macro-arguments.out

@@ -13,12 +13,20 @@
 \2: <2 +  2>
 \3: <3>
 
+'mac a':
+\1: <a>
+
 'mac ':
 
+'mac ,':
+\1: <>
+
+'mac a':
+\1: <a>
+
 'mac a,,':
 \1: <a>
 \2: <>
-\3: <>
 
 'mac ,,z':
 \1: <>
@@ -30,17 +38,21 @@
 \2: <>
 \3: <z>
 
-'mac ,a,b,c,':
+'mac ,a,b,c':
 \1: <>
 \2: <a>
 \3: <b>
 \4: <c>
-\5: <>
 
-'mac ,,x,,':
+'mac ,,x,,,':
 \1: <>
 \2: <>
 \3: <x>
 \4: <>
 \5: <>
 
+'mac E,O,F':
+\1: <E>
+\2: <O>
+\3: <F>
+

test/asm/trailing-commas.asm

@@ -0,0 +1,25 @@
+SECTION "test", ROM0
+
+mac: MACRO
+	println "\#"
+ENDM
+
+	mac 1,2, 3 , ,5,
+
+	db 1,2,3,
+	dw 4,5,6,
+	dl 7,8,9,
+	ds 10, $a, $b, $c,
+
+	print "Hello", " ",
+	println "world", "!",
+
+spam:
+eggs:
+lobsterThermidor:
+
+	export spam, eggs,
+	purge lobsterThermidor,
+
+	opt boO, g.xX#,
+	dw %ooOOOOoo, `XX##..xx,

test/asm/trailing-commas.err

@@ -0,0 +1,2 @@
+warning: trailing-commas.asm(7): [-Wempty-macro-arg]
+    Empty macro argument

test/asm/trailing-commas.out

@@ -0,0 +1,2 @@
+1,2,3,,5
+Hello world!