Bugfixes in macro expansion:

1. If expansion fails, don't crash.
2. Accept duplicate named arguments, the last one wins.

assemble.c

@@ -350,6 +350,10 @@ do_mcalled_macro:
             list_location(stack->top, DOT);
 
             macstr = expandmacro(stack->top, (MACRO *) op, ncp);
+            if (macstr == NULL) {
+                /* Error in expanding the macro, stop now. */
+                return 0;
+            }
 
             stack_push(stack, macstr); /* Push macro expansion
                                           onto input stream */

macros.c

@@ -478,15 +478,19 @@ STREAM         *expandmacro(
         label = get_symbol(cp, &nextcp, NULL);
         if (label && (nextcp = skipwhite(nextcp), *nextcp == '=') && (macarg = find_arg(mac->args, label))) {
             /* Check if I've already got a value for it */
-            if (find_arg(args, label) != NULL) {
+            if ((arg = find_arg(args, label)) != NULL) {
-                report(refstr, "Duplicate submission of keyword " "argument %s\n", label);
+                /* Duplicate is legal; the last one wins. */
-                free(label);
+                if (arg->value) {
-                free_args(args);
+                    free (arg->value);
-                return NULL;
+                    arg->value = NULL;
+                }
+            }
+            else {
+                arg = new_arg();
+                arg->label = label;
+                arg->next = args;
+                args = arg;
             }
-
-            arg = new_arg();
-            arg->label = label;
             nextcp = skipwhite(nextcp + 1);
             arg->value = getstring_macarg(refstr, nextcp, &nextcp);
         } else {
@@ -506,6 +510,8 @@ STREAM         *expandmacro(
             nextcp = skipwhite (cp);
             arg = new_arg();
             arg->label = memcheck(strdup(macarg->label));       /* Copy the name */
+            arg->next = args;
+            args = arg;
             if (*nextcp != ',') {
                 arg->value = getstring_macarg(refstr, cp, &nextcp);
             }
@@ -515,9 +521,6 @@ STREAM         *expandmacro(
             nargs++;                   /* Count nonkeyword arguments only. */
         }
 
-        arg->next = args;
-        args = arg;
-
         /* If there is a trailing comma, there is an empty last argument */
         cp = skipdelim_comma(nextcp, &onemore);
     }

tests/test-macro-comma.lst.ok

@@ -77,15 +77,41 @@
        1        000003                          .narg   label	; second arg is "default"
       53 000000                                 tstarg   1,2,3  ; 3 args
        1        000003                          .narg   label	; second arg is "2"
-      53                                
+      54                                
+      55                                ;
+      56                                ; Test default args and strange commas
+      57                                ;
+      58                                	.macro	tstdef	a=1,b=2
+      59                                	.word	a,b
+      60                                	.endm
+      61                                
+      62 000000                         	tstdef
+       1 000000 000001  000002          	.word	1,2
+      63 000004                         	tstdef	4,5
+       1 000004 000004  000005          	.word	4,5
+      64 000010                         	tstdef	4,5,6		; Excess argument is ignored
+       1 000010 000004  000005          	.word	4,5
+      65 000014                         	tstdef	b=42
+       1 000014 000001  000042          	.word	1,42
+      66 000020                         	tstdef	a=73
+       1 000020 000073  000002          	.word	73,2
+      67 000024                         	tstdef	,b=11
+       1 000024 000001  000011          	.word	1,11
+      68 000030                         	tstdef	a=5,b=4
+       1 000030 000005  000004          	.word	5,4
+      69 000034                         	tstdef	,a=5,b=4	; Strange case seen in some sources
+       1 000034 000005  000004          	.word	5,4
+      70 000040                         	tstdef	a=5,a=4		; Duplicate keyword argument -- legal!
+       1 000040 000004  000002          	.word	4,2
+      70                                
 
 
 Symbol table
 
-.       000000R      001 LABEL = 000003           START   000000R      001 
+.       000044R      001 LABEL = 000003           START   000000R      001 
 
 
 Program sections:
 
 . ABS.  000000    000   (RW,I,GBL,ABS,OVR,NOSAV)
-        000000    001   (RW,I,LCL,REL,CON,NOSAV)
+        000044    001   (RW,I,LCL,REL,CON,NOSAV)

tests/test-macro-comma.mac

@@ -51,3 +51,20 @@ start:  tstarg          ; 0 args
         tstarg   ,,3    ; 3 args
         tstarg   1,,3   ; 3 args
         tstarg   1,2,3  ; 3 args
+
+;
+; Test default args and strange commas
+;
+	.macro	tstdef	a=1,b=2
+	.word	a,b
+	.endm
+
+	tstdef
+	tstdef	4,5
+	tstdef	4,5,6		; Excess argument is ignored
+	tstdef	b=42
+	tstdef	a=73
+	tstdef	,b=11
+	tstdef	a=5,b=4
+	tstdef	,a=5,b=4	; Strange case seen in some sources
+	tstdef	a=5,a=4		; Duplicate keyword argument -- legal!