Don't wrap feature detection macros with QT_HAS_FOO() variants

Using wrappers for these macros is problematic when for example passing the
-frewrite-includes flag to preprocess sources before shipping off to distcc
or Icecream. It will also start producing warnings when compilers implement
http://eel.is/c++draft/cpp.cond#7.sentence-2. See for example
https://reviews.llvm.org/D49091

Both https://clang.llvm.org/docs/LanguageExtensions.html and the SD-6 document at
https://isocpp.org/std/standing-documents/sd-6-sg10-feature-test-recommendations
recommend defining '__has_foo(x) 0' as a fallback for compilers without the
macros, so that's what we go for.

Change-Id: I0298cd3b4a6ff6618821e34642a5ddd6728be767
Reviewed-by: Alex Richardson <arichardson.kde@gmail.com>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

1 files changed, 3 insertions, 3 deletions

diff --git a/src/corelib/serialization/qcborvalue.h b/src/corelib/serialization/qcborvalue.h
index f79fc572c4..914103b0a5 100644
--- a/src/corelib/serialization/qcborvalue.h
+++ b/src/corelib/serialization/qcborvalue.h
@@ -59,7 +59,7 @@
 #  undef False
 #endif
 
-#if 0 && QT_HAS_INCLUDE(<compare>)
+#if 0 && __has_include(<compare>)
 #  include <compare>
 #endif
 
@@ -261,7 +261,7 @@ public:
     QCborValueRef operator[](const QString & key);
 
     int compare(const QCborValue &other) const;
-#if 0 && QT_HAS_INCLUDE(<compare>)
+#if 0 && __has_include(<compare>)
     std::strong_ordering operator<=>(const QCborValue &other) const
     {
         int c = compare(other);
@@ -411,7 +411,7 @@ public:
 
     int compare(const QCborValue &other) const
     { return concrete().compare(other); }
-#if 0 && QT_HAS_INCLUDE(<compare>)
+#if 0 && __has_include(<compare>)
     std::strong_ordering operator<=>(const QCborValue &other) const
     {
         int c = compare(other);