5 files changed, 54 insertions, 2 deletions
diff --git a/libmisc/CMakeLists.txt b/libmisc/CMakeLists.txt
index 0c5c019..1f30906 100644
--- a/libmisc/CMakeLists.txt
+++ b/libmisc/CMakeLists.txt
@@ -5,4 +5,7 @@
 
 add_library(libmisc INTERFACE)
 target_include_directories(libmisc SYSTEM INTERFACE ${CMAKE_CURRENT_SOURCE_DIR}/include)
+target_sources(libmisc INTERFACE
+	assert.c
+)
 target_compile_options(libmisc INTERFACE "$<$<COMPILE_LANGUAGE:C>:-fplan9-extensions>")
diff --git a/libmisc/assert.c b/libmisc/assert.c
new file mode 100644
index 0000000..7817ba3
--- /dev/null
+++ b/libmisc/assert.c
@@ -0,0 +1,23 @@
+/* libmisc/assert.h - More assertions
+ *
+ * Copyright (C) 2024  Luke T. Shumaker <lukeshu@lukeshu.com>
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+
+#include <stdio.h>  /* for fprintf(), stderr */
+#include <stdlib.h> /* for abort() */
+
+#include <libmisc/assert.h>
+
+#ifndef NDEBUG
+__attribute__((__noreturn__)) void
+__assert_msg_fail(const char *expr,
+                  const char *file, unsigned int line, const char *func,
+                  const char *msg) {
+	fprintf(stderr, "error: %s:%u:%s(): assertion \"%s\" failed%s%s\n",
+	        file, line, func,
+	        expr,
+	        msg ? ": " : "", msg);
+	abort();
+}
+#endif
diff --git a/libmisc/include/libmisc/assert.h b/libmisc/include/libmisc/assert.h
new file mode 100644
index 0000000..e7e0eb0
--- /dev/null
+++ b/libmisc/include/libmisc/assert.h
@@ -0,0 +1,24 @@
+/* libmisc/assert.h - More assertions
+ *
+ * Copyright (C) 2024  Luke T. Shumaker <lukeshu@lukeshu.com>
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+
+#ifndef _LIBMISC_ASSERT_H_
+#define _LIBMISC_ASSERT_H_
+
+#ifdef NDEBUG
+#	define assert_msg(expr, msg) ((void)0)
+#else
+#	define assert_msg(expr, msg) do { if (!(expr)) __assert_msg_fail(#expr, __FILE__, __LINE__, __func__, msg); } while (0)
+__attribute__((__noreturn__)) void
+__assert_msg_fail(const char *expr,
+                  const char *file, unsigned int line, const char *func,
+                  const char *msg);
+#endif
+
+#define assert(expr)             assert_msg(expr, NULL) /* C89, POSIX-2001 */
+#define assert_notreached(msg)   do { assert_msg(false, "not reached"); __builtin_unreachable(); } while (0)
+#define static_assert            _Static_assert /* C11 */
+
+#endif /* _LIBMISC_ASSERT_H_ */
diff --git a/libmisc/include/libmisc/endian.h b/libmisc/include/libmisc/endian.h
index 24d7d42..b1bc55c 100644
--- a/libmisc/include/libmisc/endian.h
+++ b/libmisc/include/libmisc/endian.h
@@ -7,9 +7,10 @@
 #ifndef _LIBMISC_ENDIAN_H_
 #define _LIBMISC_ENDIAN_H_
 
-#include <assert.h>
 #include <stdint.h> /* for uint{n}_t */
 
+#include <libmisc/assert.h>
+
 /* Big endian *****************************************************************/
 
 typedef struct {
diff --git a/libmisc/include/libmisc/vcall.h b/libmisc/include/libmisc/vcall.h
index ea9402e..9b54c06 100644
--- a/libmisc/include/libmisc/vcall.h
+++ b/libmisc/include/libmisc/vcall.h
@@ -7,9 +7,10 @@
 #ifndef _LIBMISC_VCALL_H_
 #define _LIBMISC_VCALL_H_
 
-#include <assert.h> /* for assert() and static_assert() */
 #include <stddef.h> /* for offsetof() */
 
+#include <libmisc/assert.h>
+
 #define VCALL(o, m, ...)                                     \
 	({                                                   \
 		assert(o);                                   \