wcc: c-side mangles private decls; main exempt as entry-point convention

cmd/wcc/lex.c

@@ -94,6 +94,27 @@ skipws(Lex *l)
 			continue;
 		}
 		if (c == '/' && lpeek(l, 1) == '/') {
+			lget(l); lget(l);	/* consume '//' */
+			/* `// MODULE: foo` directive emitted by the ww
+			 * driver before each source-file's section in
+			 * combined.ww. Captured so cgen can mangle
+			 * non-exported symbols by module. */
+			if (lpeek(l, 0) == ' '
+			    && lpeek(l, 1) == 'M' && lpeek(l, 2) == 'O'
+			    && lpeek(l, 3) == 'D' && lpeek(l, 4) == 'U'
+			    && lpeek(l, 5) == 'L' && lpeek(l, 6) == 'E'
+			    && lpeek(l, 7) == ':' && lpeek(l, 8) == ' ') {
+				for (int i = 0; i < 9; i++) lget(l);
+				u64 start = l->pos;
+				while ((c = lpeek(l, 0)) >= 0
+				    && c != '\n' && c != '\r')
+					lget(l);
+				u64 n = l->pos - start;
+				char *m = amalloc(l->a, n + 1);
+				memcpy(m, l->src + start, n);
+				m[n] = '\0';
+				l->module = m;
+			}
 			while ((c = lpeek(l, 0)) >= 0 && c != '\n')
 				lget(l);
 			continue;