From d3a8eb1ae2f2fd87c8f1be8c5110caaa725a9d47 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Oliver=20St=C3=B6neberg?=
 <firewave@users.noreply.github.com>
Date: Wed, 15 Nov 2023 15:31:12 +0100
Subject: [PATCH] config.h: improved and cleaned up some preprocessor checks
 (#5663)

---
 gui/translationhandler.cpp |  2 +-
 lib/config.h               | 53 ++++++++++++++++++++++++--------------
 lib/sourcelocation.h       |  8 +-----
 3 files changed, 36 insertions(+), 27 deletions(-)

diff --git a/gui/translationhandler.cpp b/gui/translationhandler.cpp
index 2e17148fd..0caa3dcb1 100644
--- a/gui/translationhandler.cpp
+++ b/gui/translationhandler.cpp
@@ -32,7 +32,7 @@
 
 
 // Provide own translations for standard buttons. This (garbage) code is needed to enforce them to appear in .ts files even after "lupdate gui.pro"
-static UNUSED void unused()
+UNUSED static void unused()
 {
     Q_UNUSED(QT_TRANSLATE_NOOP("QPlatformTheme", "OK"))
     Q_UNUSED(QT_TRANSLATE_NOOP("QPlatformTheme", "Cancel"))
diff --git a/lib/config.h b/lib/config.h
index 6cb34b5e4..5379eada4 100644
--- a/lib/config.h
+++ b/lib/config.h
@@ -41,8 +41,26 @@
 #  include <crtdbg.h>
 #endif
 
+// compatibility macros
+#ifndef __has_builtin
+#define __has_builtin(x) 0
+#endif
+
+#ifndef __has_include
+#define __has_include(x) 0
+#endif
+
+#ifndef __has_cpp_attribute
+#define __has_cpp_attribute(x) 0
+#endif
+
+#ifndef __has_feature
+#define __has_feature(x) 0
+#endif
+
 // C++11 noexcept
-#if (defined(__GNUC__) && (__GNUC__ >= 5)) \
+#if defined(__cpp_noexcept_function_type) || \
+    (defined(__GNUC__) && (__GNUC__ >= 5)) \
     || defined(__clang__) \
     || defined(__CPPCHECK__)
 #  define NOEXCEPT noexcept
@@ -51,25 +69,21 @@
 #endif
 
 // C++11 noreturn
-#if defined __has_cpp_attribute
-#  if __has_cpp_attribute (noreturn)
-#    define NORETURN [[noreturn]]
-#  endif
-#endif
-#if !defined(NORETURN)
-#  if (defined(__GNUC__) && (__GNUC__ >= 5)) \
+#if __has_cpp_attribute (noreturn) \
+    || (defined(__GNUC__) && (__GNUC__ >= 5)) \
     || defined(__clang__) \
     || defined(__CPPCHECK__)
-#    define NORETURN [[noreturn]]
-#  elif defined(__GNUC__)
-#    define NORETURN __attribute__((noreturn))
-#  else
-#    define NORETURN
-#  endif
+#  define NORETURN [[noreturn]]
+#elif defined(__GNUC__)
+#  define NORETURN __attribute__((noreturn))
+#else
+#  define NORETURN
 #endif
 
 // fallthrough
-#if defined(__clang__)
+#if __cplusplus >= 201703L && __has_cpp_attribute (fallthrough)
+#  define FALLTHROUGH [[fallthrough]]
+#elif defined(__clang__)
 #  define FALLTHROUGH [[clang::fallthrough]]
 #elif (defined(__GNUC__) && (__GNUC__ >= 7))
 #  define FALLTHROUGH __attribute__((fallthrough))
@@ -78,7 +92,9 @@
 #endif
 
 // unused
-#if defined(__GNUC__) \
+#if __cplusplus >= 201703L && __has_cpp_attribute (maybe_unused)
+#  define UNUSED [[maybe_unused]]
+#elif defined(__GNUC__) \
     || defined(__clang__) \
     || defined(__CPPCHECK__)
 #  define UNUSED __attribute__((unused))
@@ -87,7 +103,8 @@
 #endif
 
 // warn_unused
-#if (defined(__clang__) && (__clang_major__ >= 15))
+#if __has_cpp_attribute (gnu::warn_unused) || \
+    (defined(__clang__) && (__clang_major__ >= 15))
 #  define WARN_UNUSED [[gnu::warn_unused]]
 #else
 #  define WARN_UNUSED
@@ -110,11 +127,9 @@ static const std::string emptyString;
 #define nonneg
 #endif
 
-#if defined(__has_feature)
 #if __has_feature(address_sanitizer)
 #define ASAN 1
 #endif
-#endif
 
 #ifndef ASAN
 #ifdef  __SANITIZE_ADDRESS__
diff --git a/lib/sourcelocation.h b/lib/sourcelocation.h
index f94fa7907..759f30d15 100644
--- a/lib/sourcelocation.h
+++ b/lib/sourcelocation.h
@@ -19,13 +19,7 @@
 #ifndef sourcelocationH
 #define sourcelocationH
 
-#ifndef __has_builtin
-#define __has_builtin(x) 0 // Compatibility with non-clang compilers.
-#endif
-
-#ifndef __has_include
-#define __has_include(x) 0 // Compatibility with non-clang compilers.
-#endif
+#include "config.h"
 
 #ifdef __CPPCHECK__
 #define CPPCHECK_HAS_SOURCE_LOCATION 0