Avoid calling style_Set/Reset before strerror(errno),

since they may call `isatty` which can change `errno`

Fixes #1857

include/verbosity.hpp

@@ -3,17 +3,14 @@
 #ifndef RGBDS_VERBOSITY_HPP
 #define RGBDS_VERBOSITY_HPP
 
+#include <stdarg.h>
 #include <stdio.h>
 
-#include "style.hpp"
-
 // This macro does not evaluate its arguments unless the condition is true.
 #define verbosePrint(level, ...) \
 	do { \
 		if (checkVerbosity(level)) { \
-			style_Set(stderr, STYLE_MAGENTA, false); \
+			printVerbosely(__VA_ARGS__); \
-			fprintf(stderr, __VA_ARGS__); \
-			style_Reset(stderr); \
 		} \
 	} while (0)
 
@@ -30,6 +27,9 @@ enum Verbosity {
 void incrementVerbosity();
 bool checkVerbosity(Verbosity level);
 
+[[gnu::format(printf, 1, 2)]]
+void printVerbosely(char const *fmt, ...);
+
 void printVVVVVVerbosity();
 
 #endif // RGBDS_VERBOSITY_HPP

src/cli.cpp

@@ -21,10 +21,11 @@ static std::vector<size_t>
 
 	std::filebuf file;
 	if (!file.open(path, std::ios_base::in)) {
+		int errnum = errno;
 		style_Set(stderr, STYLE_RED, true);
 		fputs("FATAL: ", stderr);
 		style_Reset(stderr);
-		fprintf(stderr, "Failed to open at-file \"%s\": %s\n", path.c_str(), strerror(errno));
+		fprintf(stderr, "Failed to open at-file \"%s\": %s\n", path.c_str(), strerror(errnum));
 		usage.printAndExit(1);
 	}
 

src/verbosity.cpp

@@ -24,6 +24,15 @@ void incrementVerbosity() {
 	}
 }
 
+void printVerbosely(char const *fmt, ...) {
+	va_list args;
+	style_Set(stderr, STYLE_MAGENTA, false);
+	va_start(args, fmt);
+	vfprintf(stderr, fmt, args);
+	va_end(args);
+	style_Reset(stderr);
+}
+
 void printVVVVVVerbosity() {
 	if (!checkVerbosity(VERB_VVVVVV)) {
 		return;