Symbol names with more than two '.'s could be defined as constants

Dot-only names could also trip an assertion in `make develop`
when used as labels

include/asm/symbol.hpp

@@ -68,6 +68,8 @@ struct Symbol {
 	uint32_t getConstantValue() const;
 };
 
+bool sym_IsDotScope(std::string const &symName);
+
 void sym_ForEach(void (*callback)(Symbol &));
 
 Symbol *sym_AddLocalLabel(std::string const &symName);

src/asm/lexer.cpp

@@ -1295,7 +1295,7 @@ static Token readIdentifier(char firstChar, bool raw) {
 	}
 
 	// Label scopes `.` and `..` are the only nonlocal identifiers that start with a dot
-	if (identifier.find_first_not_of('.') == identifier.npos) {
+	if (sym_IsDotScope(identifier)) {
 		tokenType = T_(SYMBOL);
 	}
 
@@ -1939,11 +1939,12 @@ static Token yylex_NORMAL() {
 
 			// `token` is either a `SYMBOL` or a `LOCAL`, and both have a `std::string` value.
 			assume(std::holds_alternative<std::string>(token.value));
+			std::string const &identifier = std::get<std::string>(token.value);
 
 			// Raw symbols and local symbols cannot be string expansions
 			if (!raw && token.type == T_(SYMBOL) && lexerState->expandStrings) {
 				// Attempt string expansion
-				if (Symbol const *sym = sym_FindExactSymbol(std::get<std::string>(token.value));
+				if (Symbol const *sym = sym_FindExactSymbol(identifier);
 				    sym && sym->type == SYM_EQUS) {
 					beginExpansion(sym->getEqus(), sym->name);
 					continue; // Restart, reading from the new buffer
@@ -1954,6 +1955,7 @@ static Token yylex_NORMAL() {
 			// - label definitions (which are followed by a ':' and use the token `LABEL`)
 			// - quiet macro invocations (which are followed by a '?' and use the token `QMACRO`)
 			// - regular macro invocations (which use the token `SYMBOL`)
+			// - label scopes "." and ".." (which use the token `SYMBOL` no matter what)
 			//
 			// If we had one `IDENTIFIER` token, the parser would need to perform "lookahead" to
 			// determine which rule applies. But since macros need to enter "raw" mode to parse
@@ -1964,7 +1966,7 @@ static Token yylex_NORMAL() {
 			// one to lex depending on the character *immediately* following the identifier.
 			// Thus "name:" is a label definition, and "name?" is a quiet macro invocation, but
 			// "name :" and "name ?" and just "name" are all regular macro invocations.
-			if (token.type == T_(SYMBOL)) {
+			if (token.type == T_(SYMBOL) && !sym_IsDotScope(identifier)) {
 				c = peek();
 				token.type = c == ':' ? T_(LABEL) : c == '?' ? T_(QMACRO) : T_(SYMBOL);
 			}

src/asm/symbol.cpp

@@ -53,6 +53,12 @@ bool sym_IsPC(Symbol const *sym) {
 	return sym == PCSymbol;
 }
 
+bool sym_IsDotScope(std::string const &symName) {
+	// Label scopes `.` and `..` are the only nonlocal identifiers that start with a dot.
+	// Three or more dots are considered a nonsensical local label.
+	return symName == "." || symName == "..";
+}
+
 void sym_ForEach(void (*callback)(Symbol &)) {
 	for (auto &it : symbols) {
 		callback(it.second);
@@ -215,8 +221,8 @@ static void redefinedError(Symbol const &sym) {
 
 static void assumeAlreadyExpanded(std::string const &symName) {
 	// Either the symbol name is `Global.local` or entirely '.'s (for scopes `.` and `..`),
-	// but cannot be unqualified `.local`
-	assume(!symName.starts_with('.') || symName.find_first_not_of('.') == symName.npos);
+	// but cannot be unqualified `.local` or more than two '.'s
+	assume(!symName.starts_with('.') || sym_IsDotScope(symName));
 }
 
 static Symbol &createSymbol(std::string const &symName) {
@@ -253,7 +259,7 @@ static bool isAutoScoped(std::string const &symName) {
 	}
 
 	// Label scopes `.` and `..` are the only nonlocal identifiers that start with a dot
-	if (dotPos == 0 && symName.find_first_not_of('.') == symName.npos) {
+	if (sym_IsDotScope(symName)) {
 		return false;
 	}
 

test/asm/dots-constant.asm

@@ -0,0 +1,2 @@
+section "test", rom0
+def #... equs "sublocal"

test/asm/dots-constant.err

@@ -0,0 +1,3 @@
+error: syntax error, unexpected local label, expecting symbol
+    at dots-constant.asm(2)
+Assembly aborted with 1 error!

test/asm/dots-interpolate.asm

@@ -0,0 +1,2 @@
+section "test", rom0
+println "{...}"

test/asm/dots-interpolate.err

@@ -0,0 +1,2 @@
+FATAL: `...` is a nonsensical reference to a nested local label
+    at dots-interpolate.asm(2)

test/asm/dots-label.asm

@@ -0,0 +1,2 @@
+section "test", rom0
+#...:

test/asm/dots-label.err

@@ -0,0 +1,2 @@
+FATAL: `...` is a nonsensical reference to a nested local label
+    at dots-label.asm(2)

test/asm/dots-macro-arg.asm

@@ -0,0 +1,4 @@
+MACRO test
+	println "\<...>"
+ENDM
+	test 1, 2, 3, 4

test/asm/dots-macro-arg.err

@@ -0,0 +1,2 @@
+FATAL: `...` is a nonsensical reference to a nested local label
+    at dots-macro-arg.asm::test(2) <- dots-macro-arg.asm(4)

test/asm/label-scope.asm

@@ -16,3 +16,17 @@ ASSERT DEF(@) && DEF(.) && DEF(..) && DEF(Foo) && DEF(.bar)
 PRINTLN "PC: {#05X:@}"
 PRINTLN "global scope: \"{.}\" ({#05X:{.}})"
 PRINTLN "local scope: \"{..}\" ({#05X:{..}})"
+
+SECTION "can't redefine", ROM0
+
+#.
+#.:
+#.?
+DEF #. EQUS "global"
+jp #.
+
+#..
+#..:
+#..?
+DEF #.. EQUS "local"
+jp #..

test/asm/label-scope.err

@@ -10,4 +10,32 @@ error: Built-in symbol `.` cannot be purged
     at label-scope.asm(12)
 error: Built-in symbol `..` cannot be purged
     at label-scope.asm(12)
-Assembly aborted with 6 errors!
+error: `.` is not a macro
+    at label-scope.asm(22)
+error: `.` is not a macro
+    at label-scope.asm(23)
+error: `.` is not a macro
+    at label-scope.asm(24)
+error: `.` is reserved for a built-in symbol
+    at label-scope.asm(25)
+error: `.` has no value outside of a label scope
+    at label-scope.asm(26)
+warning: Treating strings as numbers is deprecated; use character literals or `CHARVAL` instead [-Wobsolete]
+    at label-scope.asm(26)
+error: Strings as numbers must be a single charmap unit
+    at label-scope.asm(26)
+error: `..` is not a macro
+    at label-scope.asm(28)
+error: `..` is not a macro
+    at label-scope.asm(29)
+error: `..` is not a macro
+    at label-scope.asm(30)
+error: `..` is reserved for a built-in symbol
+    at label-scope.asm(31)
+error: `..` has no value outside of a local label scope
+    at label-scope.asm(32)
+warning: Treating strings as numbers is deprecated; use character literals or `CHARVAL` instead [-Wobsolete]
+    at label-scope.asm(32)
+error: Strings as numbers must be a single charmap unit
+    at label-scope.asm(32)
+Assembly aborted with 18 errors!