From 8fce97ea1cb3a4ba3c05e2b293a68039ce2a6ba7 Mon Sep 17 00:00:00 2001
From: nmlgc <nmlgc@nmlgc.net>
Date: Thu, 9 Jun 2022 17:03:49 +0200
Subject: [PATCH] [Maintenance] Add a static_assert() polyfill to platform.h

Part of P0198, funded by Lmocinemod and Ember2528.
---
 platform.h                  |  5 +++++
 th05/main/bullet/b6ball.cpp |  2 +-
 th05/main/custom.h          | 10 +++++-----
 3 files changed, 11 insertions(+), 6 deletions(-)

diff --git a/platform.h b/platform.h
index da2024ed..ee4ddcae 100644
--- a/platform.h
+++ b/platform.h
@@ -31,6 +31,11 @@ typedef void ( far pascal * far   farfunc_t_far)(void);
 #endif
 /// ----------
 
+// Message-less static_assert() wasn't available until C++17
+#if (__cplusplus < 201703L)
+	#define static_assert(condition) ((void)sizeof(char[1 - 2*!(condition)]))
+#endif
+
 // Both Turbo C++ and master.lib use uint16_t for segment values throughout
 // their APIs instead of the more sensible void __seg*. Maybe, integer
 // arithmetic on segment values was widely considered more important than
diff --git a/th05/main/bullet/b6ball.cpp b/th05/main/bullet/b6ball.cpp
index 5b2a68a8..1cbae1fd 100644
--- a/th05/main/bullet/b6ball.cpp
+++ b/th05/main/bullet/b6ball.cpp
@@ -30,7 +30,7 @@ void near b6balls_add(void)
 
 void near b6balls_update(void)
 {
-	CUSTOM_VERIFY(b6ball_t, B6BALL_COUNT);
+	custom_assert_count(b6ball_t, B6BALL_COUNT);
 
 	b6ball_t near *p;
 	int i;
diff --git a/th05/main/custom.h b/th05/main/custom.h
index a7647c20..8f2fb577 100644
--- a/th05/main/custom.h
+++ b/th05/main/custom.h
@@ -20,8 +20,8 @@ typedef struct {
 
 extern custom_t custom_entities[CUSTOM_COUNT];
 
-#define CUSTOM_VERIFY(derived_type, derived_count) \
-	((void)sizeof(char[1 - 2*!!( \
-		(sizeof(derived_type) * derived_count) \
-		> (sizeof(custom_t) * CUSTOM_COUNT) \
-	)]))
+#define custom_assert_count(derived_type, derived_count) \
+	static_assert( \
+		(sizeof(derived_type) * derived_count) <= \
+		(sizeof(custom_t) * CUSTOM_COUNT) \
+	)