From 3345a1fc6e87cd910602ec0f428073632d2f1ad1 Mon Sep 17 00:00:00 2001
From: Tavian Barnes <tavianator@tavianator.com>
Date: Tue, 4 Mar 2025 13:05:16 -0500
Subject: diag: Don't leave unused assertion messages in the binary

Rather than hiding them with %.0s, use a ternary to replace them with an
empty string if they would be unused.
---
 src/diag.h    | 25 +++++++++++++++++++------
 tests/tests.h | 16 ++++++++--------
 2 files changed, 27 insertions(+), 14 deletions(-)

diff --git a/src/diag.h b/src/diag.h
index a8ee911..645dbb1 100644
--- a/src/diag.h
+++ b/src/diag.h
@@ -88,6 +88,12 @@ void bfs_abortf(const char *format, ...);
 #  define bfs_ebug bfs_eabort
 #endif
 
+/**
+ * Get the default assertion message, if no format string was specified.
+ */
+#define BFS_DIAG_MSG_(format, str) \
+	(sizeof(format) > 1 ? "" : str)
+
 /**
  * Unconditional assert.
  */
@@ -95,11 +101,14 @@ void bfs_abortf(const char *format, ...);
 	bfs_verify_(#__VA_ARGS__, __VA_ARGS__, "", )
 
 #define bfs_verify_(str, cond, format, ...) \
-	((cond) ? (void)0 : bfs_abortf( \
+	((cond) ? (void)0 : bfs_verify__(format, BFS_DIAG_MSG_(format, str), __VA_ARGS__))
+
+#define bfs_verify__(format, ...) \
+	bfs_abortf( \
 		sizeof(format) > 1 \
-			? BFS_DIAG_FORMAT_("%.0s" format "%s") \
+			? BFS_DIAG_FORMAT_("%s" format "%s") \
 			: BFS_DIAG_FORMAT_("Assertion failed: `%s`"), \
-		BFS_DIAG_ARGS_(str, __VA_ARGS__)))
+		BFS_DIAG_ARGS_(__VA_ARGS__))
 
 /**
  * Unconditional assert, including the last error.
@@ -107,12 +116,16 @@ void bfs_abortf(const char *format, ...);
 #define bfs_everify(...) \
 	bfs_everify_(#__VA_ARGS__, __VA_ARGS__, "", )
 
+
 #define bfs_everify_(str, cond, format, ...) \
-	((cond) ? (void)0 : bfs_abortf( \
+	((cond) ? (void)0 : bfs_everify__(format, BFS_DIAG_MSG_(format, str), __VA_ARGS__))
+
+#define bfs_everify__(format, ...) \
+	bfs_abortf( \
 		sizeof(format) > 1 \
-			? BFS_DIAG_FORMAT_("%.0s" format "%s: %s") \
+			? BFS_DIAG_FORMAT_("%s" format "%s: %s") \
 			: BFS_DIAG_FORMAT_("Assertion failed: `%s`: %s"), \
-		BFS_DIAG_ARGS_(str, __VA_ARGS__ errstr(), )))
+		BFS_DIAG_ARGS_(__VA_ARGS__ errstr(), ))
 
 /**
  * Assert in debug builds; no-op in release builds.
diff --git a/tests/tests.h b/tests/tests.h
index 8b7d691..d395c7c 100644
--- a/tests/tests.h
+++ b/tests/tests.h
@@ -48,13 +48,13 @@ bool bfs_check_impl(bool result);
 	bfs_check_(#__VA_ARGS__, __VA_ARGS__, "", )
 
 #define bfs_check_(str, cond, format, ...) \
-	bfs_check_impl((cond) || (bfs_check__(str, format, __VA_ARGS__), false))
+	bfs_check_impl((cond) || (bfs_check__(format, BFS_DIAG_MSG_(format, str),  __VA_ARGS__), false))
 
-#define bfs_check__(str, format, ...) \
+#define bfs_check__(format, ...) \
 	bfs_diagf(sizeof(format) > 1 \
-			? BFS_DIAG_FORMAT_("%.0s" format "%s") \
+			? BFS_DIAG_FORMAT_("%s" format "%s") \
 			: BFS_DIAG_FORMAT_("Check failed: `%s`"), \
-		BFS_DIAG_ARGS_(str, __VA_ARGS__))
+		BFS_DIAG_ARGS_(__VA_ARGS__))
 
 /**
  * Check a condition, logging the current error string on failure.
@@ -63,12 +63,12 @@ bool bfs_check_impl(bool result);
 	bfs_echeck_(#__VA_ARGS__, __VA_ARGS__, "", )
 
 #define bfs_echeck_(str, cond, format, ...) \
-	bfs_check_impl((cond) || (bfs_echeck__(str, format, __VA_ARGS__), false))
+	bfs_check_impl((cond) || (bfs_echeck__(format, BFS_DIAG_MSG_(format, str), __VA_ARGS__), false))
 
-#define bfs_echeck__(str, format, ...) \
+#define bfs_echeck__(format, ...) \
 	bfs_diagf(sizeof(format) > 1 \
-			? BFS_DIAG_FORMAT_("%.0s" format "%s: %s") \
+			? BFS_DIAG_FORMAT_("%s" format "%s: %s") \
 			: BFS_DIAG_FORMAT_("Check failed: `%s`: %s"), \
-		BFS_DIAG_ARGS_(str, __VA_ARGS__ errstr(), ))
+		BFS_DIAG_ARGS_(__VA_ARGS__ errstr(), ))
 
 #endif // BFS_TESTS_H
-- 
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