Change how print(c) formats reported characters

Printable ASCII becomes single-quoted, using backslash
escapes if necessary. Unprintable characters use 0xNN
formatting, without quotes.

src/asm/lexer.c

@@ -1172,7 +1172,7 @@ static void readLineContinuation(void)
 		} else if (c == ';') {
 			discardComment();
 		} else {
-			error("Begun line continuation, but encountered character '%s'\n",
+			error("Begun line continuation, but encountered character %s\n",
 			      print(c));
 			return;
 		}
@@ -1631,7 +1631,7 @@ static void readString(void)
 				break;
 
 			default:
-				error("Illegal character escape '%s'\n", print(c));
+				error("Illegal character escape %s\n", print(c));
 				shiftChars(1);
 				break;
 			}
@@ -1781,7 +1781,7 @@ static size_t appendStringLiteral(size_t i)
 				break;
 
 			default:
-				error("Illegal character escape '%s'\n", print(c));
+				error("Illegal character escape %s\n", print(c));
 				shiftChars(1);
 				break;
 			}
@@ -2069,7 +2069,7 @@ static int yylex_NORMAL(void)
 			/* Do not report weird characters when capturing, it'll be done later */
 			if (!lexerState->capturing) {
 				/* TODO: try to group reportings */
-				error("Unknown character '%s'\n", print(c));
+				error("Unknown character %s\n", print(c));
 			}
 		}
 		lexerState->atLineStart = false;
@@ -2157,7 +2157,7 @@ static int yylex_RAW(void)
 			 */
 
 			default:
-				error("Illegal character escape '%s'\n", print(c));
+				error("Illegal character escape %s\n", print(c));
 				break;
 			}
 			/* fallthrough */

src/asm/util.c

@@ -32,35 +32,43 @@ uint32_t calchash(const char *s)
 
 char const *print(int c)
 {
-	static char buf[5]; /* '\xNN' + '\0' */
+	// "'A'" + '\0': 4 bytes
+	// "'\\n'" + '\0': 5 bytes
+	// "0xFF" + '\0': 5 bytes
+	static char buf[5];
 
 	if (c == EOF)
 		return "EOF";
 
 	if (isprint(c)) {
-		buf[0] = c;
+		buf[0] = '\'';
-		buf[1] = '\0';
+		buf[1] = c;
+		buf[2] = '\'';
+		buf[3] = '\0';
 		return buf;
 	}
 
-	buf[0] = '\\';
 	switch (c) {
 	case '\n':
-		buf[1] = 'n';
+		buf[2] = 'n';
 		break;
 	case '\r':
-		buf[1] = 'r';
+		buf[2] = 'r';
 		break;
 	case '\t':
-		buf[1] = 't';
+		buf[2] = 't';
 		break;
 
 	default: /* Print as hex */
+		buf[0] = '0';
 		buf[1] = 'x';
-		sprintf(&buf[2], "%02hhx", (uint8_t)c);
+		snprintf(&buf[2], 3, "%02hhX", (uint8_t)c); // includes the '\0'
 		return buf;
 	}
-	buf[2] = '\0';
+	buf[0] = '\'';
+	buf[1] = '\\';
+	buf[3] = '\'';
+	buf[4] = '\0';
 	return buf;
 }
 

test/asm/garbage_char.err

@@ -1,3 +1,3 @@
 ERROR: garbage_char.asm(1):
-    Unknown character '\xff'
+    Unknown character 0xFF
 error: Assembly aborted (1 error)!

test/asm/invalid-utf-8.err

@@ -1,5 +1,5 @@
 ERROR: invalid-utf-8.asm(6) -> invalid-utf-8.asm::m(4):
-    Unknown character '\xcf'
+    Unknown character 0xCF
 ERROR: invalid-utf-8.asm(6) -> invalid-utf-8.asm::m(4):
-    Unknown character '\xd3'
+    Unknown character 0xD3
 error: Assembly aborted (2 errors)!

test/asm/null-in-macro.err

@@ -1,3 +1,3 @@
 ERROR: null-in-macro.asm(4) -> null-in-macro.asm::foo(2):
-    Unknown character '\x00'
+    Unknown character 0x00
 error: Assembly aborted (1 error)!