Compiler crash when compiling c code in a library without --obj-out #1503.

lib/std/crypto/dh.c3

@@ -0,0 +1,12 @@
+module std::crypto::dh;
+import std::math::bigint;
+
+fn BigInt generate_secret(BigInt p, BigInt x, BigInt y)
+{
+	return y.mod_pow(x, p);
+}
+
+fn BigInt public_key(BigInt p, BigInt g, BigInt x)
+{
+	return g.mod_pow(x, p);
+}

releasenotes.md

@@ -71,6 +71,7 @@
 - Detect recursion errors on non-recursive mutexes in safe mode.
 - Foreach over distinct pointer failed to be caught as error #1506.
 - Foreach over distinct iterable would ignore operator(len).
+- Compiler crash when compiling c code in a library without --obj-out #1503.
 
 ### Stdlib changes
 - Additional init functions for hashmap.

src/compiler/linker.c

@@ -872,8 +872,8 @@ const char *cc_compiler(const char *cc, const char *file, const char *flags, con
 {
 	const char *dir = compiler.build.object_file_dir;
 	if (!dir) dir = compiler.build.build_dir;
-	if (output_subdir) dir = file_append_path(dir, output_subdir);
-	dir_make(dir);
+	if (output_subdir) dir = dir ? file_append_path(dir, output_subdir) : output_subdir;
+	if (dir) dir_make(dir);
 	bool is_cl_exe = str_eq(cc, "cl.exe");
 	char *filename = NULL;
 	bool split_worked = file_namesplit(file, &filename, NULL);