Use colored/styled text output for diagnostics and usage info (#1775)

Makefile

@@ -52,6 +52,7 @@ all: rgbasm rgblink rgbfix rgbgfx
 common_obj := \
 	src/extern/getopt.o \
 	src/diagnostics.o \
+	src/style.o \
 	src/usage.o
 
 rgbasm_obj := \

include/platform.hpp

@@ -28,6 +28,7 @@
 	#define STDERR_FILENO 2
 	#define ssize_t       int
 	#define SSIZE_MAX     INT_MAX
+	#define isatty        _isatty
 #else
 	#include <fcntl.h>  // IWYU pragma: export
 	#include <limits.h> // IWYU pragma: export

include/style.hpp

@@ -0,0 +1,42 @@
+// SPDX-License-Identifier: MIT
+
+#ifndef RGBDS_STYLE_HPP
+#define RGBDS_STYLE_HPP
+
+#include <stdio.h>
+
+#if defined(_MSC_VER) || defined(__MINGW32__) || defined(__CYGWIN__)
+	#define STYLE_ANSI 0
+#else
+	#define STYLE_ANSI 1
+#endif
+
+enum StyleColor {
+#if STYLE_ANSI
+	// Values analogous to ANSI foreground and background SGR colors
+	STYLE_BLACK,
+	STYLE_RED,
+	STYLE_GREEN,
+	STYLE_YELLOW,
+	STYLE_BLUE,
+	STYLE_MAGENTA,
+	STYLE_CYAN,
+	STYLE_GRAY,
+#else
+	// Values analogous to `FOREGROUND_*` constants from `windows.h`
+	STYLE_BLACK,
+	STYLE_BLUE,    // bit 0
+	STYLE_GREEN,   // bit 1
+	STYLE_CYAN,    // STYLE_BLUE | STYLE_GREEN
+	STYLE_RED,     // bit 2
+	STYLE_MAGENTA, // STYLE_BLUE | STYLE_RED
+	STYLE_YELLOW,  // STYLE_GREEN | STYLE_RED
+	STYLE_GRAY,    // STYLE_BLUE | STYLE_GREEN | STYLE_RED
+#endif
+};
+
+void style_Enable(bool enable);
+void style_Set(FILE *file, StyleColor color, bool bold);
+void style_Reset(FILE *file);
+
+#endif // RGBDS_STYLE_HPP

include/usage.hpp

@@ -4,12 +4,14 @@
 #define RGBDS_USAGE_HPP
 
 #include <stdarg.h>
+#include <string>
+#include <utility>
+#include <vector>
 
-class Usage {
+struct Usage {
-	char const *usage;
+	std::string name;
-
+	std::vector<std::string> flags;
-public:
+	std::vector<std::pair<std::vector<std::string>, std::vector<std::string>>> options;
-	Usage(char const *usage_) : usage(usage_) {}
 
 	[[noreturn]]
 	void printAndExit(int code) const;

man/rgbasm.1

@@ -10,6 +10,7 @@
 .Nm
 .Op Fl EhVvw
 .Op Fl b Ar chars
+.Op Fl \-color Ar when
 .Op Fl D Ar name Ns Op = Ns Ar value
 .Op Fl g Ar chars
 .Op Fl I Ar path
@@ -65,6 +66,18 @@ letters,
 .Sq # ,
 or
 .Sq @ .
+.It Fl \-color Ar when
+Specify when to highlight warning and error messages with color:
+.Ql always ,
+.Ql never ,
+or
+.Ql auto .
+.Ql auto
+determines whether to use colors based on the
+.Ql Lk https://no-color.org/ NO_COLOR
+or
+.Ql Lk https://force-color.org/ FORCE_COLOR
+environment variables, or whether the output is to a TTY.
 .It Fl D Ar name Ns Oo = Ns Ar value Oc , Fl \-define Ar name Ns Oo = Ns Ar value Oc
 Add a string symbol to the compiled source code.
 This is equivalent to

man/rgbfix.1

@@ -10,6 +10,7 @@
 .Nm
 .Op Fl hjOsVvw
 .Op Fl C | c
+.Op Fl \-color Ar when
 .Op Fl f Ar fix_spec
 .Op Fl i Ar game_id
 .Op Fl k Ar licensee_str
@@ -46,13 +47,13 @@ can be a path to a file, or
 to read from standard input.
 .Pp
 Note that options can be abbreviated as long as the abbreviation is unambiguous:
-.Fl \-color-o
+.Fl \-verb
 is
-.Fl \-color-only ,
+.Fl \-verbose ,
 but
-.Fl \-color
+.Fl \-ver
 is invalid because it could also be
-.Fl \-color-compatible .
+.Fl \-version .
 Options later in the command line override those set earlier.
 Accepted options are as follows:
 .Bl -tag -width Ds
@@ -70,6 +71,18 @@ to 0x80.
 This overrides
 .Fl c
 if it was set prior.
+.It Fl \-color Ar when
+Specify when to highlight warning and error messages with color:
+.Ql always ,
+.Ql never ,
+or
+.Ql auto .
+.Ql auto
+determines whether to use colors based on the
+.Ql Lk https://no-color.org/ NO_COLOR
+or
+.Ql Lk https://force-color.org/ FORCE_COLOR
+environment variables, or whether the output is to a TTY.
 .It Fl f Ar fix_spec , Fl \-fix-spec Ar fix_spec
 Fix certain header values that the Game Boy checks for correctness.
 Alternatively, intentionally trash these values by writing their binary inverse instead.

man/rgbgfx.1

@@ -15,6 +15,7 @@
 .Op Fl a Ar attrmap | Fl A
 .Op Fl b Ar base_ids
 .Op Fl c Ar pal_spec
+.Op Fl \-color Ar when
 .Op Fl d Ar depth
 .Op Fl i Ar input_tiles
 .Op Fl L Ar slice
@@ -195,6 +196,18 @@ See
 .Sx PALETTE SPECIFICATION FORMATS
 for a list of formats and their descriptions.
 .El
+.It Fl \-color Ar when
+Specify when to highlight warning and error messages with color:
+.Ql always ,
+.Ql never ,
+or
+.Ql auto .
+.Ql auto
+determines whether to use colors based on the
+.Ql Lk https://no-color.org/ NO_COLOR
+or
+.Ql Lk https://force-color.org/ FORCE_COLOR
+environment variables, or whether the output is to a TTY.
 .It Fl d Ar depth , Fl \-depth Ar depth
 Set the bit depth of the output tile data, in bits per pixel (bpp), either 1 or 2 (the default).
 This changes how tile data is output, and the maximum number of colors per palette (2 and 4 respectively).

man/rgblink.1

@@ -9,6 +9,7 @@
 .Sh SYNOPSIS
 .Nm
 .Op Fl dhMtVvwx
+.Op Fl \-color Ar when
 .Op Fl l Ar linker_script
 .Op Fl m Ar map_file
 .Op Fl n Ar sym_file
@@ -63,6 +64,18 @@ is invalid because it could also be
 .Fl \-version .
 The arguments are as follows:
 .Bl -tag -width Ds
+.It Fl \-color Ar when
+Specify when to highlight warning and error messages with color:
+.Ql always ,
+.Ql never ,
+or
+.Ql auto .
+.Ql auto
+determines whether to use colors based on the
+.Ql Lk https://no-color.org/ NO_COLOR
+or
+.Ql Lk https://force-color.org/ FORCE_COLOR
+environment variables, or whether the output is to a TTY.
 .It Fl d , Fl \-dmg
 Enable DMG mode.
 Prohibit the use of sections that doesn't exist on a DMG, such as VRAM bank 1.

src/CMakeLists.txt

@@ -5,6 +5,7 @@ configure_file(version.cpp _version.cpp ESCAPE_QUOTES)
 set(common_src
     "extern/getopt.cpp"
     "diagnostics.cpp"
+    "style.cpp"
     "usage.cpp"
     "_version.cpp"
     )

src/asm/charmap.cpp

@@ -72,7 +72,7 @@ bool charmap_ForEach(
 		});
 
 		mapFunc(charmap.name);
-		for (auto [nodeIdx, mapping] : mappings) {
+		for (auto const &[nodeIdx, mapping] : mappings) {
 			charFunc(mapping, charmap.nodes[nodeIdx].value);
 		}
 	}

src/asm/fstack.cpp

@@ -15,6 +15,7 @@
 #include "helpers.hpp"
 #include "linkdefs.hpp"
 #include "platform.hpp" // S_ISDIR (stat macro)
+#include "style.hpp"
 #include "verbosity.hpp"
 
 #include "asm/lexer.hpp"
@@ -63,19 +64,27 @@ std::string const &FileStackNode::dump(uint32_t curLineNo) const {
 	if (std::holds_alternative<std::vector<uint32_t>>(data)) {
 		assume(parent); // REPT nodes use their parent's name
 		std::string const &lastName = parent->dump(lineNo);
+		style_Set(stderr, STYLE_CYAN, false);
 		fputs(" -> ", stderr);
+		style_Set(stderr, STYLE_CYAN, true);
 		fputs(lastName.c_str(), stderr);
 		fputs(reptChain().c_str(), stderr);
+		style_Set(stderr, STYLE_CYAN, false);
 		fprintf(stderr, "(%" PRIu32 ")", curLineNo);
+		style_Reset(stderr);
 		return lastName;
 	} else {
 		if (parent) {
 			parent->dump(lineNo);
+			style_Set(stderr, STYLE_CYAN, false);
 			fputs(" -> ", stderr);
 		}
 		std::string const &nodeName = name();
+		style_Set(stderr, STYLE_CYAN, true);
 		fputs(nodeName.c_str(), stderr);
+		style_Set(stderr, STYLE_CYAN, false);
 		fprintf(stderr, "(%" PRIu32 ")", curLineNo);
+		style_Reset(stderr);
 		return nodeName;
 	}
 }

src/asm/lexer.cpp

@@ -18,6 +18,7 @@
 #include <unordered_map>
 
 #include "helpers.hpp"
+#include "style.hpp"
 #include "util.hpp"
 #include "verbosity.hpp"
 
@@ -845,9 +846,15 @@ void lexer_DumpStringExpansions() {
 	for (Expansion &exp : lexerState->expansions) {
 		// Only register EQUS expansions, not string args
 		if (exp.name) {
-			fprintf(stderr, "while expanding symbol \"%s\"\n", exp.name->c_str());
+			style_Set(stderr, STYLE_CYAN, false);
+			fputs("while expanding symbol \"", stderr);
+			style_Set(stderr, STYLE_CYAN, true);
+			fputs(exp.name->c_str(), stderr);
+			style_Set(stderr, STYLE_CYAN, false);
+			fputs("\"\n", stderr);
 		}
 	}
+	style_Reset(stderr);
 }
 
 // Functions to discard non-tokenized characters

src/asm/main.cpp

@@ -15,6 +15,7 @@
 #include "extern/getopt.hpp"
 #include "helpers.hpp"
 #include "parser.hpp" // Generated from parser.y
+#include "style.hpp"
 #include "usage.hpp"
 #include "util.hpp" // UpperMap
 #include "verbosity.hpp"
@@ -36,7 +37,7 @@ static std::unordered_map<std::string, std::vector<StateFeature>> stateFileSpecs
 static char const *optstring = "b:D:Eg:hI:M:o:P:p:Q:r:s:VvW:wX:";
 
 // Variables for the long-only options
-static int depType; // Variants of `-M`
+static int longOpt; // `--color` and variants of `-M`
 
 // Equivalent long options
 // Please keep in the same order as short opts.
@@ -53,11 +54,6 @@ static option const longopts[] = {
     {"help",            no_argument,       nullptr,  'h'},
     {"include",         required_argument, nullptr,  'I'},
     {"dependfile",      required_argument, nullptr,  'M'},
-    {"MC",              no_argument,       &depType, 'C'},
-    {"MG",              no_argument,       &depType, 'G'},
-    {"MP",              no_argument,       &depType, 'P'},
-    {"MQ",              required_argument, &depType, 'Q'},
-    {"MT",              required_argument, &depType, 'T'},
     {"output",          required_argument, nullptr,  'o'},
     {"preinclude",      required_argument, nullptr,  'P'},
     {"pad-value",       required_argument, nullptr,  'p'},
@@ -68,27 +64,34 @@ static option const longopts[] = {
     {"verbose",         no_argument,       nullptr,  'v'},
     {"warning",         required_argument, nullptr,  'W'},
     {"max-errors",      required_argument, nullptr,  'X'},
-    {nullptr,           no_argument,       nullptr,  0  }
+    {"color",           required_argument, &longOpt, 'c'},
+    {"MC",              no_argument,       &longOpt, 'C'},
+    {"MG",              no_argument,       &longOpt, 'G'},
+    {"MP",              no_argument,       &longOpt, 'P'},
+    {"MQ",              required_argument, &longOpt, 'Q'},
+    {"MT",              required_argument, &longOpt, 'T'},
+    {nullptr,           no_argument,       nullptr,  0  },
 };
 
-// clang-format off: long string literal
+// clang-format off: nested initializers
-static Usage usage(
+static Usage usage = {
-    "Usage: rgbasm [-EhVvw] [-b chars] [-D name[=value]] [-g chars] [-I path]\n"
+    .name = "rgbasm",
-    "              [-M depend_file] [-MC] [-MG] [-MP] [-MT target_file] [-MQ target_file]\n"
+    .flags = {
-    "              [-o out_file] [-P include_file] [-p pad_value] [-Q precision]\n"
+        "[-EhVvw]", "[-b chars]", "[-D name[=value]]", "[-g chars]", "[-I path]",
-    "              [-r depth] [-s features:state_file] [-W warning] [-X max_errors]\n"
+        "[-M depend_file]", "[-MC]", "[-MG]", "[-MP]", "[-MT target_file]", "[-MQ target_file]",
-    "              <file>\n"
+        "[-o out_file]", "[-P include_file]", "[-p pad_value]", "[-Q precision]", "[-r depth]",
-    "Useful options:\n"
+        "[-s features:state_file]", "[-W warning]", "[-X max_errors]", "<file>",
-    "    -E, --export-all               export all labels\n"
+    },
-    "    -M, --dependfile <path>        set the output dependency file\n"
+    .options = {
-    "    -o, --output <path>            set the output object file\n"
+        {{"-E", "--export-all"}, {"export all labels"}},
-    "    -p, --pad-value <value>        set the value to use for `ds'\n"
+        {{"-M", "--dependfile <path>"}, {"set the output dependency file"}},
-    "    -s, --state <features>:<path>  set an output state file\n"
+        {{"-o", "--output <path>"}, {"set the output object file"}},
-    "    -V, --version                  print RGBASM version and exit\n"
+        {{"-p", "--pad-value <value>"}, {"set the value to use for `ds'"}},
-    "    -W, --warning <warning>        enable or disable warnings\n"
+        {{"-s", "--state <features>:<path>"}, {"set an output state file"}},
-    "\n"
+        {{"-V", "--version"}, {"print RGBASM version and exit"}},
-    "For help, use `man rgbasm' or go to https://rgbds.gbdev.io/docs/\n"
+        {{"-W", "--warning <warning>"}, {"enable or disable warnings"}},
-);
+    },
+};
 // clang-format on
 
 // LCOV_EXCL_START
@@ -160,7 +163,7 @@ static void verboseOutputConfig(int argc, char *argv[]) {
 		    "char",
 		    "macro",
 		};
-		for (auto [name, features] : stateFileSpecs) {
+		for (auto const &[name, features] : stateFileSpecs) {
 			fprintf(stderr, "\t - %s: ", name == "-" ? "<stdout>" : name.c_str());
 			for (size_t i = 0; i < features.size(); ++i) {
 				if (i > 0) {
@@ -449,7 +452,17 @@ int main(int argc, char *argv[]) {
 
 		// Long-only options
 		case 0:
-			switch (depType) {
+			switch (longOpt) {
+			case 'c':
+				if (!strcasecmp(musl_optarg, "always")) {
+					style_Enable(true);
+				} else if (!strcasecmp(musl_optarg, "never")) {
+					style_Enable(false);
+				} else if (strcasecmp(musl_optarg, "auto")) {
+					fatal("Invalid argument for option '--color'");
+				}
+				break;
+
 			case 'C':
 				options.missingIncludeState = GEN_CONTINUE;
 				break;
@@ -465,7 +478,7 @@ int main(int argc, char *argv[]) {
 			case 'Q':
 			case 'T': {
 				std::string newTarget = musl_optarg;
-				if (depType == 'Q') {
+				if (longOpt == 'Q') {
 					newTarget = escapeMakeChars(newTarget);
 				}
 				if (!options.targetFileName.empty()) {
@@ -549,7 +562,7 @@ int main(int argc, char *argv[]) {
 
 	out_WriteObject();
 
-	for (auto [name, features] : stateFileSpecs) {
+	for (auto const &[name, features] : stateFileSpecs) {
 		out_WriteState(name, features);
 	}
 

src/asm/warning.cpp

@@ -12,6 +12,7 @@
 #include "diagnostics.hpp"
 #include "helpers.hpp"
 #include "itertools.hpp"
+#include "style.hpp"
 
 #include "asm/fstack.hpp"
 #include "asm/lexer.hpp"
@@ -64,14 +65,24 @@ Diagnostics<WarningLevel, WarningID> warnings = {
 // clang-format on
 
 static void printDiag(
-    char const *fmt, va_list args, char const *type, char const *flagfmt, char const *flag
+    char const *fmt,
+    va_list args,
+    char const *type,
+    StyleColor color,
+    char const *flagfmt,
+    char const *flag
 ) {
-	fputs(type, stderr);
+	style_Set(stderr, color, true);
-	fputs(": ", stderr);
+	fprintf(stderr, "%s: ", type);
 	if (fstk_DumpCurrent()) {
+		putc(':', stderr);
+		if (flagfmt) {
+			style_Set(stderr, color, true);
 			fprintf(stderr, flagfmt, flag);
+		}
 		fputs("\n    ", stderr);
 	}
+	style_Reset(stderr);
 	vfprintf(stderr, fmt, args);
 	putc('\n', stderr);
 
@@ -82,13 +93,16 @@ static void incrementErrors() {
 	// This intentionally makes 0 act as "unlimited"
 	warnings.incrementErrors();
 	if (warnings.nbErrors == options.maxErrors) {
+		style_Set(stderr, STYLE_RED, true);
 		fprintf(
 		    stderr,
-		    "Assembly aborted after the maximum of %" PRIu64 " error%s! (configure with "
+		    "Assembly aborted after the maximum of %" PRIu64 " error%s!",
-		    "'-X/--max-errors')\n",
 		    warnings.nbErrors,
 		    warnings.nbErrors == 1 ? "" : "s"
 		);
+		style_Set(stderr, STYLE_RED, false);
+		fputs(" (configure with '-X/--max-errors')\n", stderr);
+		style_Reset(stderr);
 		exit(1);
 	}
 }
@@ -97,17 +111,19 @@ void error(char const *fmt, ...) {
 	va_list args;
 
 	va_start(args, fmt);
-	printDiag(fmt, args, "error", ":", nullptr);
+	printDiag(fmt, args, "error", STYLE_RED, nullptr, nullptr);
 	va_end(args);
 
 	incrementErrors();
 }
 
 void error(std::function<void()> callback) {
+	style_Set(stderr, STYLE_RED, true);
 	fputs("error: ", stderr);
 	if (fstk_DumpCurrent()) {
 		fputs(":\n    ", stderr);
 	}
+	style_Reset(stderr);
 	callback();
 	putc('\n', stderr);
 	lexer_DumpStringExpansions();
@@ -120,7 +136,7 @@ void fatal(char const *fmt, ...) {
 	va_list args;
 
 	va_start(args, fmt);
-	printDiag(fmt, args, "FATAL", ":", nullptr);
+	printDiag(fmt, args, "FATAL", STYLE_RED, nullptr, nullptr);
 	va_end(args);
 
 	exit(1);
@@ -128,12 +144,14 @@ void fatal(char const *fmt, ...) {
 
 void requireZeroErrors() {
 	if (warnings.nbErrors != 0) {
+		style_Set(stderr, STYLE_RED, true);
 		fprintf(
 		    stderr,
 		    "Assembly aborted with %" PRIu64 " error%s!\n",
 		    warnings.nbErrors,
 		    warnings.nbErrors == 1 ? "" : "s"
 		);
+		style_Reset(stderr);
 		exit(1);
 	}
 }
@@ -149,11 +167,11 @@ void warning(WarningID id, char const *fmt, ...) {
 		break;
 
 	case WarningBehavior::ENABLED:
-		printDiag(fmt, args, "warning", ": [-W%s]", flag);
+		printDiag(fmt, args, "warning", STYLE_YELLOW, " [-W%s]", flag);
 		break;
 
 	case WarningBehavior::ERROR:
-		printDiag(fmt, args, "error", ": [-Werror=%s]", flag);
+		printDiag(fmt, args, "error", STYLE_RED, " [-Werror=%s]", flag);
 		break;
 	}
 

src/diagnostics.cpp

@@ -1,3 +1,5 @@
+// SPDX-License-Identifier: MIT
+
 #include "diagnostics.hpp"
 
 void warnx(char const *fmt, ...) {

src/fix/main.cpp

@@ -16,6 +16,7 @@
 #include "extern/getopt.hpp"
 #include "helpers.hpp"
 #include "platform.hpp"
+#include "style.hpp"
 #include "usage.hpp"
 #include "version.hpp"
 
@@ -27,6 +28,9 @@ static constexpr off_t BANK_SIZE = 0x4000;
 // Short options
 static char const *optstring = "Ccf:hi:jk:L:l:m:n:Oo:p:r:st:VvW:w";
 
+// Variables for the long-only options
+static int longOpt; // `--color`
+
 // Equivalent long options
 // Please keep in the same order as short opts.
 // Also, make sure long opts don't create ambiguity:
@@ -55,27 +59,34 @@ static option const longopts[] = {
     {"version",          no_argument,       nullptr,  'V'},
     {"validate",         no_argument,       nullptr,  'v'},
     {"warning",          required_argument, nullptr,  'W'},
-    {nullptr,            no_argument,       nullptr, 0  }
+    {"color",            required_argument, &longOpt, 'c'},
+    {nullptr,            no_argument,       nullptr,  0  },
 };
 
-// clang-format off: long string literal
+// clang-format off: nested initializers
-static Usage usage(
+static Usage usage = {
-    "Usage: rgbfix [-hjOsVvw] [-C | -c] [-f <fix_spec>] [-i <game_id>] [-k <licensee>]\n"
+    .name = "rgbfix",
-    "              [-L <logo_file>] [-l <licensee_byte>] [-m <mbc_type>]\n"
+    .flags = {
-    "              [-n <rom_version>] [-p <pad_value>] [-r <ram_size>] [-t <title_str>]\n"
+        "[-hjOsVvw]", "[-C | -c]", "[-f <fix_spec>]", "[-i <game_id>]", "[-k <licensee>]",
-    "              [-W warning] <file> ...\n"
+        "[-L <logo_file>]", "[-l <licensee_byte>]", "[-m <mbc_type>]", "[-n <rom_version>]",
-    "Useful options:\n"
+        "[-p <pad_value>]", "[-r <ram_size>]", "[-t <title_str>]", "[-W warning]", "<file> ...",
-    "    -m, --mbc-type <value>   set the MBC type byte to this value; `-m help'\n"
+    },
-    "                               or `-m list' prints the accepted values\n"
+    .options = {
-    "    -p, --pad-value <value>  pad to the next valid size using this value\n"
+        {
-    "    -r, --ram-size <code>    set the cart RAM size byte to this value\n"
+            {"-m", "--mbc-type <value>"},
-    "    -o, --output <path>      set the output file\n"
+            {
-    "    -V, --version            print RGBFIX version and exit\n"
+                "set the MBC type byte to this value; `-m help'",
-    "    -v, --validate           fix the header logo and both checksums (`-f lhg')\n"
+                "or `-m list' prints the accepted values",
-    "    -W, --warning <warning>  enable or disable warnings\n"
+            },
-    "\n"
+        },
-    "For help, use `man rgbfix' or go to https://rgbds.gbdev.io/docs/\n"
+        {{"-p", "--pad-value <value>"}, {"pad to the next valid size using this value"}},
-);
+        {{"-r", "--ram-size <code>"}, {"set the cart RAM size byte to this value"}},
+        {{"-o", "--output <path>"}, {"set the output file"}},
+        {{"-V", "--version"}, {"print RGBFIX version and exit"}},
+        {{"-v", "--validate"}, {"fix the header logo and both checksums (`-f lhg')"}},
+        {{"-W", "--warning <warning>"}, {"enable or disable warnings"}},
+    },
+};
 // clang-format on
 
 static uint8_t tpp1Rev[2];
@@ -817,6 +828,19 @@ int main(int argc, char *argv[]) {
 			warnings.state.warningsEnabled = false;
 			break;
 
+		// Long-only options
+		case 0:
+			if (longOpt == 'c') {
+				if (!strcasecmp(musl_optarg, "always")) {
+					style_Enable(true);
+				} else if (!strcasecmp(musl_optarg, "never")) {
+					style_Enable(false);
+				} else if (strcasecmp(musl_optarg, "auto")) {
+					fatal("Invalid argument for option '--color'");
+				}
+			}
+			break;
+
 		default:
 			usage.printAndExit(1); // LCOV_EXCL_LINE
 		}

src/fix/mbc.cpp

@@ -1,3 +1,5 @@
+// SPDX-License-Identifier: MIT
+
 #include "fix/mbc.hpp"
 
 #include <stdlib.h>

src/fix/warning.cpp

@@ -1,5 +1,9 @@
+// SPDX-License-Identifier: MIT
+
 #include "fix/warning.hpp"
 
+#include "style.hpp"
+
 // clang-format off: nested initializers
 Diagnostics<WarningLevel, WarningID> warnings = {
     .metaWarnings = {
@@ -20,6 +24,7 @@ Diagnostics<WarningLevel, WarningID> warnings = {
 
 uint32_t checkErrors(char const *filename) {
 	if (warnings.nbErrors > 0) {
+		style_Set(stderr, STYLE_RED, true);
 		fprintf(
 		    stderr,
 		    "Fixing \"%s\" failed with %" PRIu64 " error%s\n",
@@ -27,13 +32,16 @@ uint32_t checkErrors(char const *filename) {
 		    warnings.nbErrors,
 		    warnings.nbErrors == 1 ? "" : "s"
 		);
+		style_Reset(stderr);
 	}
 	return warnings.nbErrors;
 }
 
 void error(char const *fmt, ...) {
 	va_list ap;
+	style_Set(stderr, STYLE_RED, true);
 	fputs("error: ", stderr);
+	style_Reset(stderr);
 	va_start(ap, fmt);
 	vfprintf(stderr, fmt, ap);
 	va_end(ap);
@@ -44,7 +52,9 @@ void error(char const *fmt, ...) {
 
 void fatal(char const *fmt, ...) {
 	va_list ap;
+	style_Set(stderr, STYLE_RED, true);
 	fputs("FATAL: ", stderr);
+	style_Reset(stderr);
 	va_start(ap, fmt);
 	vfprintf(stderr, fmt, ap);
 	va_end(ap);
@@ -62,7 +72,9 @@ void warning(WarningID id, char const *fmt, ...) {
 		break;
 
 	case WarningBehavior::ENABLED:
+		style_Set(stderr, STYLE_YELLOW, true);
 		fprintf(stderr, "warning: [-W%s]\n    ", flag);
+		style_Reset(stderr);
 		va_start(ap, fmt);
 		vfprintf(stderr, fmt, ap);
 		va_end(ap);
@@ -70,7 +82,9 @@ void warning(WarningID id, char const *fmt, ...) {
 		break;
 
 	case WarningBehavior::ERROR:
+		style_Set(stderr, STYLE_RED, true);
 		fprintf(stderr, "error: [-Werror=%s]\n    ", flag);
+		style_Reset(stderr);
 		va_start(ap, fmt);
 		vfprintf(stderr, fmt, ap);
 		va_end(ap);

src/gfx/main.cpp

@@ -18,6 +18,7 @@
 #include "extern/getopt.hpp"
 #include "file.hpp"
 #include "platform.hpp"
+#include "style.hpp"
 #include "usage.hpp"
 #include "verbosity.hpp"
 #include "version.hpp"
@@ -44,6 +45,9 @@ static struct LocalOptions {
 // Short options
 static char const *optstring = "-Aa:B:b:Cc:d:hi:L:l:mN:n:Oo:Pp:Qq:r:s:Tt:U:uVvW:wXx:YZ";
 
+// Variables for the long-only options
+static int longOpt; // `--color`
+
 // Equivalent long options
 // Please keep in the same order as short opts.
 // Also, make sure long opts don't create ambiguity:
@@ -85,26 +89,29 @@ static option const longopts[] = {
     {"trim-end",         required_argument, nullptr,  'x'},
     {"mirror-y",         no_argument,       nullptr,  'Y'},
     {"columns",          no_argument,       nullptr,  'Z'},
-    {nullptr,            no_argument,       nullptr, 0  }
+    {"color",            required_argument, &longOpt, 'c'},
+    {nullptr,            no_argument,       nullptr,  0  },
 };
 
-// clang-format off: long string literal
+// clang-format off: nested initializers
-static Usage usage(
+static Usage usage = {
-    "Usage: rgbgfx [-r stride] [-ChmOuVXYZ] [-v [-v ...]] [-a <attr_map> | -A]\n"
+    .name = "rgbgfx",
-    "       [-b <base_ids>] [-c <colors>] [-d <depth>] [-i <tileset_file>]\n"
+    .flags = {
-    "       [-L <slice>] [-l <base_pal>] [-N <nb_tiles>] [-n <nb_pals>]\n"
+        "[-r stride]", "[-ChmOuVXYZ]", "[-v [-v ...]]", "[-a <attr_map> | -A]", "[-b <base_ids>]",
-    "       [-o <out_file>] [-p <pal_file> | -P] [-q <pal_map> | -Q]\n"
+        "[-c <colors>]", "[-d <depth>]", "[-i <tileset_file>]", "[-L <slice>]", "[-l <base_pal>]",
-    "       [-s <nb_colors>] [-t <tile_map> | -T] [-x <nb_tiles>] <file>\n"
+        "[-N <nb_tiles>]", "[-n <nb_pals>]", "[-o <out_file>]", "[-p <pal_file> | -P]",
-    "Useful options:\n"
+        "[-q <pal_map> | -Q]", "[-s <nb_colors>]", "[-t <tile_map> | -T]", "[-x <nb_tiles>]",
-    "    -m, --mirror-tiles       optimize out mirrored tiles\n"
+        "<file>",
-    "    -o, --output <path>      output the tile data to this path\n"
+    },
-    "    -t, --tilemap <path>     output the tile map to this path\n"
+    .options = {
-    "    -u, --unique-tiles       optimize out identical tiles\n"
+        {{"-m", "--mirror-tiles"}, {"optimize out mirrored tiles"}},
-    "    -V, --version            print RGBGFX version and exit\n"
+        {{"-o", "--output <path>"}, {"output the tile data to this path"}},
-    "    -W, --warning <warning>  enable or disable warnings\n"
+        {{"-t", "--tilemap <path>"}, {"output the tile map to this path"}},
-    "\n"
+        {{"-u", "--unique-tiles"}, {"optimize out identical tiles"}},
-    "For help, use `man rgbgfx' or go to https://rgbds.gbdev.io/docs/\n"
+        {{"-V", "--version"}, {"print RGBGFX version and exit"}},
-);
+        {{"-W", "--warning <warning>"}, {"enable or disable warnings"}},
+    },
+};
 // clang-format on
 
 // Parses a number at the beginning of a string, moving the pointer to skip the parsed characters.
@@ -552,6 +559,17 @@ static char *parseArgv(int argc, char *argv[]) {
 		case 'Z':
 			options.columnMajor = true;
 			break;
+		case 0: // Long-only options
+			if (longOpt == 'c') {
+				if (!strcasecmp(musl_optarg, "always")) {
+					style_Enable(true);
+				} else if (!strcasecmp(musl_optarg, "never")) {
+					style_Enable(false);
+				} else if (strcasecmp(musl_optarg, "auto")) {
+					fatal("Invalid argument for option '--color'");
+				}
+			}
+			break;
 		case 1: // Positional argument, requested by leading `-` in opt string
 			if (musl_optarg[0] == '@') {
 				// Instruct the caller to process that at-file

src/gfx/process.cpp

@@ -630,7 +630,7 @@ static void outputUnoptimizedTileData(
 	uint64_t nbKeptTiles = nbTiles > options.trim ? nbTiles - options.trim : 0;
 	uint64_t tileIdx = 0;
 
-	for (auto [tile, attr] : zip(image.visitAsTiles(), attrmap)) {
+	for (auto const &[tile, attr] : zip(image.visitAsTiles(), attrmap)) {
 		// Do not emit fully-background tiles.
 		if (attr.isBackgroundTile()) {
 			++tileIdx;
@@ -799,7 +799,7 @@ static UniqueTiles dedupTiles(
 	}
 
 	bool inputWithoutOutput = !options.inputTileset.empty() && options.output.empty();
-	for (auto [tile, attr] : zip(image.visitAsTiles(), attrmap)) {
+	for (auto const &[tile, attr] : zip(image.visitAsTiles(), attrmap)) {
 		if (attr.isBackgroundTile()) {
 			attr.xFlip = false;
 			attr.yFlip = false;

src/gfx/warning.cpp

@@ -7,6 +7,8 @@
 #include <stdio.h>
 #include <stdlib.h>
 
+#include "style.hpp"
+
 // clang-format off: nested initializers
 Diagnostics<WarningLevel, WarningID> warnings = {
     .metaWarnings = {
@@ -25,12 +27,14 @@ Diagnostics<WarningLevel, WarningID> warnings = {
 
 [[noreturn]]
 void giveUp() {
+	style_Set(stderr, STYLE_RED, true);
 	fprintf(
 	    stderr,
 	    "Conversion aborted after %" PRIu64 " error%s\n",
 	    warnings.nbErrors,
 	    warnings.nbErrors == 1 ? "" : "s"
 	);
+	style_Reset(stderr);
 	exit(1);
 }
 
@@ -42,7 +46,9 @@ void requireZeroErrors() {
 
 void error(char const *fmt, ...) {
 	va_list ap;
+	style_Set(stderr, STYLE_RED, true);
 	fputs("error: ", stderr);
+	style_Reset(stderr);
 	va_start(ap, fmt);
 	vfprintf(stderr, fmt, ap);
 	va_end(ap);
@@ -54,7 +60,9 @@ void error(char const *fmt, ...) {
 [[noreturn]]
 void fatal(char const *fmt, ...) {
 	va_list ap;
+	style_Set(stderr, STYLE_RED, true);
 	fputs("FATAL: ", stderr);
+	style_Reset(stderr);
 	va_start(ap, fmt);
 	vfprintf(stderr, fmt, ap);
 	va_end(ap);
@@ -73,7 +81,9 @@ void warning(WarningID id, char const *fmt, ...) {
 		break;
 
 	case WarningBehavior::ENABLED:
+		style_Set(stderr, STYLE_YELLOW, true);
 		fprintf(stderr, "warning: [-W%s]\n    ", flag);
+		style_Reset(stderr);
 		va_start(ap, fmt);
 		vfprintf(stderr, fmt, ap);
 		va_end(ap);
@@ -81,7 +91,9 @@ void warning(WarningID id, char const *fmt, ...) {
 		break;
 
 	case WarningBehavior::ERROR:
+		style_Set(stderr, STYLE_RED, true);
 		fprintf(stderr, "error: [-Werror=%s]\n    ", flag);
+		style_Reset(stderr);
 		va_start(ap, fmt);
 		vfprintf(stderr, fmt, ap);
 		va_end(ap);

src/link/main.cpp

@@ -16,6 +16,7 @@
 #include "itertools.hpp"
 #include "platform.hpp"
 #include "script.hpp" // Generated from script.y
+#include "style.hpp"
 #include "usage.hpp"
 #include "util.hpp" // UpperMap, printChar
 #include "verbosity.hpp"
@@ -37,6 +38,9 @@ static char const *linkerScriptName = nullptr; // -l
 // Short options
 static char const *optstring = "dhl:m:Mn:O:o:p:S:tVvW:wx";
 
+// Variables for the long-only options
+static int longOpt; // `--color`
+
 // Equivalent long options
 // Please keep in the same order as short opts.
 // Also, make sure long opts don't create ambiguity:
@@ -61,26 +65,28 @@ static option const longopts[] = {
     {"warning",       required_argument, nullptr,  'W'},
     {"wramx",         no_argument,       nullptr,  'w'},
     {"nopad",         no_argument,       nullptr,  'x'},
-    {nullptr,         no_argument,       nullptr, 0  }
+    {"color",         required_argument, &longOpt, 'c'},
+    {nullptr,         no_argument,       nullptr,  0  },
 };
 
-// clang-format off: long string literal
+// clang-format off: nested initializers
-static Usage usage(
+static Usage usage = {
-    "Usage: rgblink [-dhMtVvwx] [-l script] [-m map_file] [-n sym_file]\n"
+    .name = "rgblink",
-    "               [-O overlay_file] [-o out_file] [-p pad_value]\n"
+    .flags = {
-    "               [-S spec] <file> ...\n"
+        "[-dhMtVvwx]", "[-l script]", "[-m map_file]", "[-n sym_file]", "[-O overlay_file]",
-    "Useful options:\n"
+        "[-o out_file]", "[-p pad_value]", "[-S spec]", "<file> ...",
-    "    -l, --linkerscript <path>  set the input linker script\n"
+    },
-    "    -m, --map <path>           set the output map file\n"
+    .options = {
-    "    -n, --sym <path>           set the output symbol list file\n"
+        {{"-l", "--linkerscript <path>"}, {"set the input linker script"}},
-    "    -o, --output <path>        set the output file\n"
+        {{"-m", "--map <path>"}, {"set the output map file"}},
-    "    -p, --pad <value>          set the value to pad between sections with\n"
+        {{"-n", "--sym <path>"}, {"set the output symbol list file"}},
-    "    -x, --nopad                disable padding of output binary\n"
+        {{"-o", "--output <path>"}, {"set the output file"}},
-    "    -V, --version              print RGBLINK version and exit\n"
+        {{"-p", "--pad <value>"}, {"set the value to pad between sections with"}},
-    "    -W, --warning <warning>    enable or disable warnings\n"
+        {{"-x", "--nopad"}, {"disable padding of output binary"}},
-    "\n"
+        {{"-V", "--version"}, {"print RGBLINK version and exit"}},
-    "For help, use `man rgblink' or go to https://rgbds.gbdev.io/docs/\n"
+        {{"-W", "--warning <warning>"}, {"enable or disable warnings"}},
-);
+    },
+};
 // clang-format on
 
 // LCOV_EXCL_START
@@ -174,21 +180,29 @@ std::string const &FileStackNode::dump(uint32_t curLineNo) const {
 	if (std::holds_alternative<std::vector<uint32_t>>(data)) {
 		assume(parent); // REPT nodes use their parent's name
 		std::string const &lastName = parent->dump(lineNo);
+		style_Set(stderr, STYLE_CYAN, false);
 		fputs(" -> ", stderr);
+		style_Set(stderr, STYLE_CYAN, true);
 		fputs(lastName.c_str(), stderr);
 		for (uint32_t iter : iters()) {
 			fprintf(stderr, "::REPT~%" PRIu32, iter);
 		}
+		style_Set(stderr, STYLE_CYAN, false);
 		fprintf(stderr, "(%" PRIu32 ")", curLineNo);
+		style_Reset(stderr);
 		return lastName;
 	} else {
 		if (parent) {
 			parent->dump(lineNo);
+			style_Set(stderr, STYLE_CYAN, false);
 			fputs(" -> ", stderr);
 		}
 		std::string const &nodeName = name();
+		style_Set(stderr, STYLE_CYAN, true);
 		fputs(nodeName.c_str(), stderr);
+		style_Set(stderr, STYLE_CYAN, false);
 		fprintf(stderr, "(%" PRIu32 ")", curLineNo);
+		style_Reset(stderr);
 		return nodeName;
 	}
 }
@@ -388,6 +402,17 @@ int main(int argc, char *argv[]) {
 			// implies tiny mode
 			options.is32kMode = true;
 			break;
+		case 0: // Long-only options
+			if (longOpt == 'c') {
+				if (!strcasecmp(musl_optarg, "always")) {
+					style_Enable(true);
+				} else if (!strcasecmp(musl_optarg, "never")) {
+					style_Enable(false);
+				} else if (strcasecmp(musl_optarg, "auto")) {
+					fatal("Invalid argument for option '--color'");
+				}
+			}
+			break;
 		default:
 			usage.printAndExit(1); // LCOV_EXCL_LINE
 		}

src/link/warning.cpp

@@ -5,6 +5,8 @@
 #include <inttypes.h>
 #include <stdarg.h>
 
+#include "style.hpp"
+
 #include "link/main.hpp"
 
 // clang-format off: nested initializers
@@ -33,24 +35,29 @@ static void printDiag(
     char const *fmt,
     va_list args,
     char const *type,
+    StyleColor color,
     char const *flagfmt,
     char const *flag
 ) {
+	style_Set(stderr, color, true);
 	fprintf(stderr, "%s: ", type);
 	if (src) {
 		src->dump(lineNo);
 		fputs(": ", stderr);
 	}
 	if (flagfmt) {
+		style_Set(stderr, color, true);
 		fprintf(stderr, flagfmt, flag);
 		fputs("\n    ", stderr);
 	}
+	style_Reset(stderr);
 	vfprintf(stderr, fmt, args);
 	putc('\n', stderr);
 }
 
 [[noreturn]]
 static void abortLinking(char const *verb) {
+	style_Set(stderr, STYLE_RED, true);
 	fprintf(
 	    stderr,
 	    "Linking %s with %" PRIu64 " error%s\n",
@@ -58,27 +65,28 @@ static void abortLinking(char const *verb) {
 	    warnings.nbErrors,
 	    warnings.nbErrors == 1 ? "" : "s"
 	);
+	style_Reset(stderr);
 	exit(1);
 }
 
 void warning(FileStackNode const *src, uint32_t lineNo, char const *fmt, ...) {
 	va_list args;
 	va_start(args, fmt);
-	printDiag(src, lineNo, fmt, args, "warning", nullptr, 0);
+	printDiag(src, lineNo, fmt, args, "warning", STYLE_YELLOW, nullptr, nullptr);
 	va_end(args);
 }
 
 void warning(char const *fmt, ...) {
 	va_list args;
 	va_start(args, fmt);
-	printDiag(nullptr, 0, fmt, args, "warning", nullptr, 0);
+	printDiag(nullptr, 0, fmt, args, "warning", STYLE_YELLOW, nullptr, nullptr);
 	va_end(args);
 }
 
 void error(FileStackNode const *src, uint32_t lineNo, char const *fmt, ...) {
 	va_list args;
 	va_start(args, fmt);
-	printDiag(src, lineNo, fmt, args, "error", nullptr, 0);
+	printDiag(src, lineNo, fmt, args, "error", STYLE_RED, nullptr, nullptr);
 	va_end(args);
 
 	warnings.incrementErrors();
@@ -87,7 +95,7 @@ void error(FileStackNode const *src, uint32_t lineNo, char const *fmt, ...) {
 void error(char const *fmt, ...) {
 	va_list args;
 	va_start(args, fmt);
-	printDiag(nullptr, 0, fmt, args, "error", nullptr, 0);
+	printDiag(nullptr, 0, fmt, args, "error", STYLE_RED, nullptr, nullptr);
 	va_end(args);
 
 	warnings.incrementErrors();
@@ -95,7 +103,9 @@ void error(char const *fmt, ...) {
 
 void errorNoDump(char const *fmt, ...) {
 	va_list args;
+	style_Set(stderr, STYLE_RED, true);
 	fputs("error: ", stderr);
+	style_Reset(stderr);
 	va_start(args, fmt);
 	vfprintf(stderr, fmt, args);
 	va_end(args);
@@ -104,7 +114,13 @@ void errorNoDump(char const *fmt, ...) {
 }
 
 void scriptError(char const *name, uint32_t lineNo, char const *fmt, va_list args) {
-	fprintf(stderr, "error: %s(%" PRIu32 "): ", name, lineNo);
+	style_Set(stderr, STYLE_RED, true);
+	fputs("error: ", stderr);
+	style_Set(stderr, STYLE_CYAN, true);
+	fputs(name, stderr);
+	style_Set(stderr, STYLE_CYAN, false);
+	fprintf(stderr, "(%" PRIu32 "): ", lineNo);
+	style_Reset(stderr);
 	vfprintf(stderr, fmt, args);
 	putc('\n', stderr);
 
@@ -115,7 +131,7 @@ void scriptError(char const *name, uint32_t lineNo, char const *fmt, va_list arg
 void fatal(FileStackNode const *src, uint32_t lineNo, char const *fmt, ...) {
 	va_list args;
 	va_start(args, fmt);
-	printDiag(src, lineNo, fmt, args, "FATAL", nullptr, 0);
+	printDiag(src, lineNo, fmt, args, "FATAL", STYLE_RED, nullptr, nullptr);
 	va_end(args);
 
 	warnings.incrementErrors();
@@ -126,7 +142,7 @@ void fatal(FileStackNode const *src, uint32_t lineNo, char const *fmt, ...) {
 void fatal(char const *fmt, ...) {
 	va_list args;
 	va_start(args, fmt);
-	printDiag(nullptr, 0, fmt, args, "FATAL", nullptr, 0);
+	printDiag(nullptr, 0, fmt, args, "FATAL", STYLE_RED, nullptr, nullptr);
 	va_end(args);
 
 	warnings.incrementErrors();
@@ -150,11 +166,11 @@ void warning(FileStackNode const *src, uint32_t lineNo, WarningID id, char const
 		break;
 
 	case WarningBehavior::ENABLED:
-		printDiag(src, lineNo, fmt, args, "warning", "[-W%s]", flag);
+		printDiag(src, lineNo, fmt, args, "warning", STYLE_RED, "[-W%s]", flag);
 		break;
 
 	case WarningBehavior::ERROR:
-		printDiag(src, lineNo, fmt, args, "error", "[-Werror=%s]", flag);
+		printDiag(src, lineNo, fmt, args, "error", STYLE_YELLOW, "[-Werror=%s]", flag);
 
 		warnings.incrementErrors();
 		break;

src/style.cpp

@@ -0,0 +1,98 @@
+// SPDX-License-Identifier: MIT
+
+// This implementation was based on https://github.com/agauniyal/rang/
+// and adapted for RGBDS.
+
+#include "style.hpp"
+
+#include <stdlib.h> // getenv
+#include <string.h>
+
+#include "platform.hpp" // isatty
+
+#if !STYLE_ANSI
+// clang-format off: maintain `include` order
+	#define WIN32_LEAN_AND_MEAN // Include less from `windows.h`
+	#include <windows.h>
+// clang-format on
+#endif
+
+enum Tribool { TRI_NO, TRI_YES, TRI_MAYBE };
+
+#if !STYLE_ANSI
+static const HANDLE outHandle = GetStdHandle(STD_OUTPUT_HANDLE);
+static const HANDLE errHandle = GetStdHandle(STD_ERROR_HANDLE);
+
+static const WORD defaultAttrib = []() {
+	if (CONSOLE_SCREEN_BUFFER_INFO info; GetConsoleScreenBufferInfo(outHandle, &info)
+	                                     || GetConsoleScreenBufferInfo(errHandle, &info)) {
+		return info.wAttributes;
+	}
+	return static_cast<WORD>((STYLE_BLACK << 4) | (STYLE_GRAY | 8));
+}();
+
+static HANDLE getHandle(FILE *file) {
+	return file == stdout ? outHandle : file == stderr ? errHandle : INVALID_HANDLE_VALUE;
+}
+#endif // !STYLE_ANSI
+
+static Tribool forceStyle = []() {
+	if (char const *forceColor = getenv("FORCE_COLOR");
+	    forceColor && strcmp(forceColor, "") && strcmp(forceColor, "0")) {
+		return TRI_YES;
+	}
+	if (char const *noColor = getenv("NO_COLOR");
+	    noColor && strcmp(noColor, "") && strcmp(noColor, "0")) {
+		return TRI_NO;
+	}
+	return TRI_MAYBE;
+}();
+
+static bool isTerminal(FILE *file) {
+	static bool isOutTerminal = isatty(STDOUT_FILENO);
+	static bool isErrTerminal = isatty(STDERR_FILENO);
+
+	return (file == stdout && isOutTerminal) || (file == stderr && isErrTerminal);
+}
+
+static bool allowStyle(FILE *file) {
+	return forceStyle == TRI_YES || (forceStyle == TRI_MAYBE && isTerminal(file));
+}
+
+void style_Enable(bool enable) {
+	forceStyle = enable ? TRI_YES : TRI_NO;
+}
+
+void style_Set(FILE *file, StyleColor color, bool bold) {
+	if (!allowStyle(file)) {
+		return;
+	}
+
+	// LCOV_EXCL_START
+#if STYLE_ANSI
+	fprintf(file, "\033[%dm", static_cast<int>(color) + (bold ? 90 : 30));
+#else
+	if (HANDLE handle = getHandle(file); handle != INVALID_HANDLE_VALUE) {
+		fflush(file);
+		SetConsoleTextAttribute(handle, (defaultAttrib & ~0xF) | (color | (bold ? 8 : 0)));
+	}
+#endif
+	// LCOV_EXCL_STOP
+}
+
+void style_Reset(FILE *file) {
+	if (!allowStyle(file)) {
+		return;
+	}
+
+	// LCOV_EXCL_START
+#if STYLE_ANSI
+	fputs("\033[m", file);
+#else
+	if (HANDLE handle = getHandle(file); handle != INVALID_HANDLE_VALUE) {
+		fflush(file);
+		SetConsoleTextAttribute(handle, defaultAttrib);
+	}
+#endif
+	// LCOV_EXCL_STOP
+}

src/usage.cpp

@@ -2,17 +2,111 @@
 
 #include "usage.hpp"
 
+#include <algorithm>
 #include <stdio.h>
 #include <stdlib.h>
 
+#include "helpers.hpp"
+#include "style.hpp"
+
+static constexpr size_t maxLineLen = 79;
+
+// LCOV_EXCL_START
+
 void Usage::printAndExit(int code) const {
-	fputs(usage, stderr);
+	FILE *file = code ? stderr : stdout;
+
+	// Print "Usage: <program name>"
+	style_Set(file, STYLE_GREEN, true);
+	fputs("Usage: ", file);
+	style_Set(file, STYLE_CYAN, true);
+	fputs(name.c_str(), file);
+	size_t padFlags = literal_strlen("Usage: ") + name.length();
+
+	// Print the flags after the program name, indented to the same level
+	style_Set(file, STYLE_CYAN, false);
+	size_t flagsWidth = padFlags;
+	for (std::string const &flag : flags) {
+		if (flagsWidth + 1 + flag.length() > maxLineLen) {
+			fprintf(file, "\n%*c", static_cast<int>(padFlags), ' ');
+			flagsWidth = padFlags;
+		}
+		fprintf(file, " %s", flag.c_str());
+		flagsWidth += 1 + flag.length();
+	}
+	fputs("\n\n", file);
+
+	// Measure the options' flags
+	size_t padOpts = 0;
+	for (auto const &item : options) {
+		size_t pad = 0;
+		for (size_t i = 0; i < item.first.size(); ++i) {
+			if (i > 0) {
+				pad += literal_strlen(", ");
+			}
+			pad += item.first[i].length();
+		}
+		if (pad > padOpts) {
+			padOpts = pad;
+		}
+	}
+	int optIndent = static_cast<int>(literal_strlen("    ") + padOpts);
+
+	// Print the options
+	if (!options.empty()) {
+		style_Set(file, STYLE_GREEN, true);
+		fputs("Useful options:\n", file);
+	}
+	for (auto const &[opts, description] : options) {
+		fputs("    ", file);
+
+		// Print the comma-separated options
+		size_t optWidth = 0;
+		for (size_t i = 0; i < opts.size(); ++i) {
+			if (i > 0) {
+				style_Reset(file);
+				fputs(", ", file);
+				optWidth += literal_strlen(", ");
+			}
+			style_Set(file, STYLE_CYAN, false);
+			fputs(opts[i].c_str(), file);
+			optWidth += opts[i].length();
+		}
+		if (optWidth < padOpts) {
+			fprintf(file, "%*c", static_cast<int>(padOpts - optWidth), ' ');
+		}
+
+		// Print the description lines, indented to the same level
+		for (size_t i = 0; i < description.size(); ++i) {
+			style_Reset(file);
+			if (i > 0) {
+				fprintf(file, "\n%*c", optIndent, ' ');
+			}
+			fprintf(file, "  %s", description[i].c_str());
+		}
+		putc('\n', file);
+	}
+
+	// Print the link for further help information
+	style_Reset(file);
+	fputs("\nFor more help, use `", file);
+	style_Set(file, STYLE_CYAN, true);
+	fprintf(file, "man %s", name.c_str());
+	style_Reset(file);
+	fputs("' or go to ", file);
+	style_Set(file, STYLE_BLUE, true);
+	fputs("https://rgbds.gbdev.io/docs/", file);
+	style_Reset(file);
+	putc('\n', file);
+
 	exit(code);
 }
 
 void Usage::printAndExit(char const *fmt, ...) const {
 	va_list args;
+	style_Set(stderr, STYLE_RED, true);
 	fputs("FATAL: ", stderr);
+	style_Reset(stderr);
 	va_start(args, fmt);
 	vfprintf(stderr, fmt, args);
 	va_end(args);
@@ -20,3 +114,5 @@ void Usage::printAndExit(char const *fmt, ...) const {
 
 	printAndExit(1);
 }
+
+// LCOV_EXCL_STOP

src/verbosity.cpp

@@ -1,3 +1,5 @@
+// SPDX-License-Identifier: MIT
+
 #include "verbosity.hpp"
 
 #include <array>
@@ -8,16 +10,18 @@
 
 static Verbosity verbosity = VERB_NONE;
 
+bool checkVerbosity(Verbosity level) {
+	return verbosity >= level;
+}
+
+// LCOV_EXCL_START
+
 void incrementVerbosity() {
 	if (verbosity < VERB_VVVVVV) {
 		verbosity = static_cast<Verbosity>(verbosity + 1);
 	}
 }
 
-bool checkVerbosity(Verbosity level) {
-	return verbosity >= level;
-}
-
 void printVVVVVVerbosity() {
 	if (!checkVerbosity(VERB_VVVVVV)) {
 		return;
@@ -67,3 +71,5 @@ void printVVVVVVerbosity() {
 	}
 	putc('\n', stderr);
 }
+
+// LCOV_EXCL_STOP