add a function that triggers UB if the assert() macro is suppressed to access an actual function

2 files changed, 23 insertions, 0 deletions

diff --git a/mk/assert.d b/mk/assert.d
new file mode 100644
index 00000000..aae9fcd0
--- /dev/null
+++ b/mk/assert.d
@@ -0,0 +1,10 @@
+libc_C.0: libc.a(assert.o)
+libc.a(assert.o): $(OBJDIR)/assert.o
+	@$(AR) $(ARFLAGS) $@ $(OBJDIR)/$%
+
+$(OBJDIR)/assert.o: src/assert/assert.c
+$(OBJDIR)/assert.o: src/stdlib/_stdlib.h
+$(OBJDIR)/assert.o:
+	@echo "  [CC] $@"
+	@mkdir -p $(@D)
+	@$(CC) -c -o $@ $(CFLAGS) src/assert/assert.c
diff --git a/src/assert/assert.c b/src/assert/assert.c
new file mode 100644
index 00000000..2a5551a4
--- /dev/null
+++ b/src/assert/assert.c
@@ -0,0 +1,13 @@
+#include <stdlib.h>
+#include "stdlib/_stdlib.h"
+
+_Noreturn void assert(int exp)
+{
+	(void)exp;
+	__stdlib.constraint_handler("Undefined Behavior: The assert() macro has been suppressed to access an actual function", NULL, 0);
+	abort();
+}
+
+/*
+STDC(0)
+*/