remove zig build --init. add zig init-lib and zig init-exe

init-lib creates a working static library with tests, and
init-exe creates a working hello world with a `run` target.

both now have test coverage with the new "cli tests" file.

closes #1035

src/compiler.cpp

@@ -5,6 +5,9 @@
 static Buf saved_compiler_id = BUF_INIT;
 static Buf saved_app_data_dir = BUF_INIT;
 static Buf saved_stage1_path = BUF_INIT;
+static Buf saved_lib_dir = BUF_INIT;
+static Buf saved_special_dir = BUF_INIT;
+static Buf saved_std_dir = BUF_INIT;
 
 Buf *get_stage1_cache_path() {
     if (saved_stage1_path.list.length != 0) {
@@ -64,3 +67,101 @@ Error get_compiler_id(Buf **result) {
     return ErrorNone;
 }
 
+
+static bool test_zig_install_prefix(Buf *test_path, Buf *out_zig_lib_dir) {
+    Buf lib_buf = BUF_INIT;
+    buf_init_from_str(&lib_buf, "lib");
+
+    Buf zig_buf = BUF_INIT;
+    buf_init_from_str(&zig_buf, "zig");
+
+    Buf std_buf = BUF_INIT;
+    buf_init_from_str(&std_buf, "std");
+
+    Buf index_zig_buf = BUF_INIT;
+    buf_init_from_str(&index_zig_buf, "index.zig");
+
+    Buf test_lib_dir = BUF_INIT;
+    Buf test_zig_dir = BUF_INIT;
+    Buf test_std_dir = BUF_INIT;
+    Buf test_index_file = BUF_INIT;
+
+    os_path_join(test_path, &lib_buf, &test_lib_dir);
+    os_path_join(&test_lib_dir, &zig_buf, &test_zig_dir);
+    os_path_join(&test_zig_dir, &std_buf, &test_std_dir);
+    os_path_join(&test_std_dir, &index_zig_buf, &test_index_file);
+
+    int err;
+    bool exists;
+    if ((err = os_file_exists(&test_index_file, &exists))) {
+        exists = false;
+    }
+    if (exists) {
+        buf_init_from_buf(out_zig_lib_dir, &test_zig_dir);
+        return true;
+    }
+    return false;
+}
+
+static int find_zig_lib_dir(Buf *out_path) {
+    int err;
+
+    Buf self_exe_path = BUF_INIT;
+    buf_resize(&self_exe_path, 0);
+    if (!(err = os_self_exe_path(&self_exe_path))) {
+        Buf *cur_path = &self_exe_path;
+
+        for (;;) {
+            Buf *test_dir = buf_alloc();
+            os_path_dirname(cur_path, test_dir);
+
+            if (buf_eql_buf(test_dir, cur_path)) {
+                break;
+            }
+
+            if (test_zig_install_prefix(test_dir, out_path)) {
+                return 0;
+            }
+
+            cur_path = test_dir;
+        }
+    }
+
+    return ErrorFileNotFound;
+}
+
+Buf *get_zig_lib_dir(void) {
+    if (saved_lib_dir.list.length != 0) {
+        return &saved_lib_dir;
+    }
+    buf_resize(&saved_lib_dir, 0);
+
+    int err;
+    if ((err = find_zig_lib_dir(&saved_lib_dir))) {
+        fprintf(stderr, "Unable to find zig lib directory\n");
+        exit(EXIT_FAILURE);
+    }
+    return &saved_lib_dir;
+}
+
+Buf *get_zig_std_dir() {
+    if (saved_std_dir.list.length != 0) {
+        return &saved_std_dir;
+    }
+    buf_resize(&saved_std_dir, 0);
+
+    os_path_join(get_zig_lib_dir(), buf_create_from_str("std"), &saved_std_dir);
+
+    return &saved_std_dir;
+}
+
+Buf *get_zig_special_dir() {
+    if (saved_special_dir.list.length != 0) {
+        return &saved_special_dir;
+    }
+    buf_resize(&saved_special_dir, 0);
+
+    os_path_join(get_zig_std_dir(), buf_sprintf("special"), &saved_special_dir);
+
+    return &saved_special_dir;
+}