Use a Defer struct to close files and restore lexer state with RAII (#1379)

src/link/assign.cpp

@@ -393,7 +393,7 @@ void assign_AssignSections() {
 				fprintf(stderr, "%c \"%s\"", nbSections == 0 ? ';' : ',', section->name.c_str());
 				nbSections++;
 				if (nbSections == 10)
-					goto max_out;
+					goto max_out; // Can't `break` out of a nested loop
 			}
 		}
 

src/link/main.cpp

@@ -320,7 +320,7 @@ static void parseScrambleSpec(char const *spec) {
 			argErr('S', "Cannot imply limit for region \"%.*s\"", regionNamePrintLen, regionName);
 		}
 
-next:
+next: // Can't `continue` a `for` loop with this nontrivial iteration logic
 		if (spec) {
 			assert(*spec == ',' || *spec == '\0');
 			if (*spec == ',')

src/link/object.cpp

@@ -473,7 +473,6 @@ static void readAssertion(
 
 void obj_ReadFile(char const *fileName, unsigned int fileID) {
 	FILE *file;
-
 	if (strcmp(fileName, "-")) {
 		file = fopen(fileName, "rb");
 	} else {
@@ -482,6 +481,7 @@ void obj_ReadFile(char const *fileName, unsigned int fileID) {
 	}
 	if (!file)
 		err("Failed to open file \"%s\"", fileName);
+	Defer closeFile{[&] { fclose(file); }};
 
 	// First, check if the object is a RGBDS object or a SDCC one. If the first byte is 'R',
 	// we'll assume it's a RGBDS object file, and otherwise, that it's a SDCC object file.
@@ -630,8 +630,6 @@ void obj_ReadFile(char const *fileName, unsigned int fileID) {
 			}
 		}
 	}
-
-	fclose(file);
 }
 
 void obj_CheckAssertions() {

src/link/output.cpp

@@ -199,6 +199,10 @@ static void writeROM() {
 		if (!outputFile)
 			err("Failed to open output file \"%s\"", outputFileName);
 	}
+	Defer closeOutputFile{[&] {
+		if (outputFile)
+			fclose(outputFile);
+	}};
 
 	if (overlayFileName) {
 		if (strcmp(overlayFileName, "-")) {
@@ -210,6 +214,10 @@ static void writeROM() {
 		if (!overlayFile)
 			err("Failed to open overlay file \"%s\"", overlayFileName);
 	}
+	Defer closeOverlayFile{[&] {
+		if (overlayFile)
+			fclose(overlayFile);
+	}};
 
 	uint32_t nbOverlayBanks = checkOverlaySize();
 
@@ -230,11 +238,6 @@ static void writeROM() {
 			    sectionTypeInfo[SECTTYPE_ROMX].size
 			);
 	}
-
-	if (outputFile)
-		fclose(outputFile);
-	if (overlayFile)
-		fclose(overlayFile);
 }
 
 // Checks whether this character is legal as the first character of a symbol's name in a sym file
@@ -533,6 +536,7 @@ static void writeSym() {
 	}
 	if (!symFile)
 		err("Failed to open sym file \"%s\"", symFileName);
+	Defer closeSymFile{[&] { fclose(symFile); }};
 
 	fputs("; File generated by rgblink\n", symFile);
 
@@ -542,8 +546,6 @@ static void writeSym() {
 		for (uint32_t bank = 0; bank < sections[type].size(); bank++)
 			writeSymBank(sections[type][bank], type, bank);
 	}
-
-	fclose(symFile);
 }
 
 // Writes the map file, if applicable.
@@ -559,6 +561,7 @@ static void writeMap() {
 	}
 	if (!mapFile)
 		err("Failed to open map file \"%s\"", mapFileName);
+	Defer closeMapFile{[&] { fclose(mapFile); }};
 
 	writeMapSummary();
 
@@ -568,8 +571,6 @@ static void writeMap() {
 		for (uint32_t bank = 0; bank < sections[type].size(); bank++)
 			writeMapBank(sections[type][bank], type, bank);
 	}
-
-	fclose(mapFile);
 }
 
 void out_WriteFiles() {

src/link/script.y

@@ -225,7 +225,6 @@ static uint8_t parseHexDigit(int c) {
 }
 
 yy::parser::symbol_type yylex() {
-try_again: // Can't use a `do {} while(0)` loop, otherwise compilers (wrongly) think it can end.
 	auto &context = lexerStack.back();
 	auto c = context.file.sbumpc();
 
@@ -245,7 +244,7 @@ try_again: // Can't use a `do {} while(0)` loop, otherwise compilers (wrongly) t
 		// Basically yywrap().
 		if (lexerStack.size() != 1) {
 			lexerStack.pop_back();
-			goto try_again;
+			return yylex();
 		} else if (!atEof) {
 			// Inject a newline at EOF, to avoid errors for files that don't end with one.
 			atEof = true;
@@ -353,7 +352,7 @@ try_again: // Can't use a `do {} while(0)` loop, otherwise compilers (wrongly) t
 		}
 
 		scriptError(context, "Unknown keyword \"%s\"", ident.c_str());
-		goto try_again; // Try lexing another token.
+		return yylex();
 	} else {
 		scriptError(context, "Unexpected character '%s'", printChar(c));
 		// Keep reading characters until the EOL, to avoid reporting too many errors.
@@ -363,7 +362,7 @@ try_again: // Can't use a `do {} while(0)` loop, otherwise compilers (wrongly) t
 			}
 			context.file.sbumpc();
 		}
-		goto try_again;
+		return yylex();
 	}
 	// Not marking as unreachable; this will generate a warning if any codepath forgets to return.
 }

src/link/sdas_obj.cpp

@@ -797,6 +797,10 @@ void sdobj_ReadFile(FileStackNode const &where, FILE *file, std::vector<Symbol>
 		}
 	}
 
+#undef expectEol
+#undef expectToken
+#undef getToken
+
 	if (!data.empty())
 		warning(&where, lineNo, "Last 'T' line had no 'R' line (ignored)");
 	if (fileSections.size() < expectedNbAreas)
@@ -841,10 +845,4 @@ void sdobj_ReadFile(FileStackNode const &where, FILE *file, std::vector<Symbol>
 		// Calling `sect_AddSection` invalidates the contents of `fileSections`!
 		sect_AddSection(std::move(section));
 	}
-
-#undef expectEol
-#undef expectToken
-#undef getToken
-
-	fclose(file);
 }