From 77b99e8111cdd06b4fe12f2e18950a1e40ee2b76 Mon Sep 17 00:00:00 2001 From: Fabian Kosmale Date: Fri, 22 Oct 2021 12:36:06 +0200 Subject: [PATCH] QMetaType: Avoid superfluous template instantiations Apparently msvc still parses the template and generates code for it when it encounters an extern template declaration. Thus, instead of speeding up compilation, it gets slowed down significantly as the instantiation would happen in every compilation unit that (transitively) included qmetatype.h. Task-number: QTBUG-97601 Change-Id: Id5e934afb14ad8973df1b9197aef336b22220111 Reviewed-by: Thiago Macieira --- src/corelib/kernel/qmetatype.cpp | 11 ++--------- src/corelib/kernel/qmetatype.h | 8 ++++++-- 2 files changed, 8 insertions(+), 11 deletions(-) diff --git a/src/corelib/kernel/qmetatype.cpp b/src/corelib/kernel/qmetatype.cpp index 3758d3c9416..ba301ca5222 100644 --- a/src/corelib/kernel/qmetatype.cpp +++ b/src/corelib/kernel/qmetatype.cpp @@ -2974,24 +2974,17 @@ static const QtPrivate::QMetaTypeInterface *interfaceForType(int typeId) QMetaType::QMetaType(int typeId) : QMetaType(interfaceForType(typeId)) {} namespace QtPrivate { -#ifndef QT_BOOTSTRAPPED - -#if defined(Q_CC_MSVC) && defined(QT_BUILD_CORE_LIB) -#define QT_METATYPE_TEMPLATE_EXPORT Q_CORE_EXPORT -#else -#define QT_METATYPE_TEMPLATE_EXPORT -#endif +#if !defined(QT_BOOTSTRAPPED) && !defined(Q_CC_MSVC) // Explicit instantiation definition #define QT_METATYPE_DECLARE_TEMPLATE_ITER(TypeName, Id, Name) \ - template class QT_METATYPE_TEMPLATE_EXPORT QMetaTypeForType; + template class QMetaTypeForType; QT_FOR_EACH_STATIC_PRIMITIVE_TYPE(QT_METATYPE_DECLARE_TEMPLATE_ITER) QT_FOR_EACH_STATIC_PRIMITIVE_POINTER(QT_METATYPE_DECLARE_TEMPLATE_ITER) QT_FOR_EACH_STATIC_CORE_CLASS(QT_METATYPE_DECLARE_TEMPLATE_ITER) QT_FOR_EACH_STATIC_CORE_POINTER(QT_METATYPE_DECLARE_TEMPLATE_ITER) QT_FOR_EACH_STATIC_CORE_TEMPLATE(QT_METATYPE_DECLARE_TEMPLATE_ITER) #undef QT_METATYPE_DECLARE_TEMPLATE_ITER -#undef QT_METATYPE_TEMPLATE_EXPORT #endif } diff --git a/src/corelib/kernel/qmetatype.h b/src/corelib/kernel/qmetatype.h index 346ae3667a0..669273af68a 100644 --- a/src/corelib/kernel/qmetatype.h +++ b/src/corelib/kernel/qmetatype.h @@ -2369,9 +2369,13 @@ public: }; #undef QT_METATYPE_CONSTEXPRLAMDA -#ifndef QT_BOOTSTRAPPED +/* + MSVC instantiates extern templates +(https://developercommunity.visualstudio.com/t/c11-extern-templates-doesnt-work-for-class-templat/157868) + */ +#if !defined(QT_BOOTSTRAPPED) && !defined(Q_CC_MSVC) -#if !defined(Q_CC_MSVC) || !defined(QT_BUILD_CORE_LIB) +#if !defined(QT_BUILD_CORE_LIB) #define QT_METATYPE_TEMPLATE_EXPORT Q_CORE_EXPORT #else #define QT_METATYPE_TEMPLATE_EXPORT