From 5fda1e05dc06b11055463d89719b7ce7381b4b1b Mon Sep 17 00:00:00 2001
From: Mahmoud Al-Qudsi <mqudsi@neosmart.net>
Date: Mon, 8 Feb 2021 13:48:23 -0600
Subject: [PATCH] Statically assert the sort order of input_function_metadata_t

---
 src/common.h  | 37 +++++++++++++++++++++++++++++++++++++
 src/input.cpp |  3 ++-
 2 files changed, 39 insertions(+), 1 deletion(-)

diff --git a/src/common.h b/src/common.h
index eaae8fd07..0a8728e78 100644
--- a/src/common.h
+++ b/src/common.h
@@ -716,4 +716,41 @@ struct cleanup_t {
 
 bool is_console_session();
 
+/// Compile-time agnostic-size strcmp/wcscmp implementation. Unicode-unaware.
+template <typename T>
+constexpr ssize_t const_strcmp(const T *lhs, const T *rhs) {
+    return (*lhs == *rhs) ? (*lhs == 0 ? 0 : const_strcmp(lhs + 1, rhs + 1))
+                          : (*lhs > *rhs ? 1 : -1);
+}
+static_assert(const_strcmp("", "a") < 0, "const_strcmp failure");
+static_assert(const_strcmp("a", "a") == 0, "const_strcmp failure");
+static_assert(const_strcmp("a", "") > 0, "const_strcmp failure");
+static_assert(const_strcmp("aa", "a") > 0, "const_strcmp failure");
+static_assert(const_strcmp("a", "aa") < 0, "const_strcmp failure");
+static_assert(const_strcmp("b", "aa") > 0, "const_strcmp failure");
+
+/// Compile-time agnostic-size strlen/wcslen implementation. Unicode-unaware.
+template <typename T>
+constexpr ssize_t const_strlen(const T *str) {
+    return *str == static_cast<T>(0) ? 0 : 1 + const_strlen(str + 1);
+}
+static_assert(const_strlen("") == 0, "const_strlen failure");
+static_assert(const_strlen("hello") == 5, "const_strlen failure");
+
+/// Compile-time assertion of alphabetical sort of array `array`, by specified
+/// parameter `accessor`. This is only a macro because constexpr lambdas (to
+/// specify the accessor for the sort key) are C++17 and up.
+#define ASSERT_SORT_ORDER(array, accessor) \
+    struct verify_ ## array ## _sort_t { \
+        template <class T, size_t N> \
+        constexpr static bool validate(T(&vals)[N], size_t idx = 0) { \
+            return (idx == (((sizeof(array) / sizeof(vals[0]))) - 1)) \
+                   ? true \
+                   : const_strcmp(vals[idx] accessor, vals[idx + 1] accessor) <= 0 && \
+                         verify_ ## array ## _sort_t::validate<T, N>(vals, idx + 1); \
+    } \
+}; \
+static_assert(verify_ ## array ## _sort_t::validate(array), \
+              #array " members not in asciibetical order!");
+
 #endif  // FISH_COMMON_H
diff --git a/src/input.cpp b/src/input.cpp
index 5581ae30e..25e731dc7 100644
--- a/src/input.cpp
+++ b/src/input.cpp
@@ -86,7 +86,7 @@ struct input_function_metadata_t {
 
 /// A static mapping of all readline commands as strings to their readline_cmd_t equivalent.
 /// Keep this list sorted alphabetically!
-static const input_function_metadata_t input_function_metadata[] = {
+static constexpr const input_function_metadata_t input_function_metadata[] = {
     // NULL makes it unusable - this is specially inserted when we detect mouse input
     {L"", readline_cmd_t::disable_mouse_tracking},
     {L"accept-autosuggestion", readline_cmd_t::accept_autosuggestion},
@@ -165,6 +165,7 @@ static const input_function_metadata_t input_function_metadata[] = {
     {L"yank-pop", readline_cmd_t::yank_pop},
 };
 
+ASSERT_SORT_ORDER(input_function_metadata, .name);
 static_assert(sizeof(input_function_metadata) / sizeof(input_function_metadata[0]) ==
                   input_function_count,
               "input_function_metadata size mismatch with input_common. Did you forget to update "