[libcxx-commits] [libcxx] 61bd192 - [libc++] Explicitly enumerate std::string external instantiations.
Eric Fiselier via libcxx-commits
libcxx-commits at lists.llvm.org
Thu Jan 9 12:52:58 PST 2020
Author: Eric Fiselier
Date: 2020-01-09T15:51:02-05:00
New Revision: 61bd19206f61ace4b007838a2ff8884a13ec0374
URL: https://github.com/llvm/llvm-project/commit/61bd19206f61ace4b007838a2ff8884a13ec0374
DIFF: https://github.com/llvm/llvm-project/commit/61bd19206f61ace4b007838a2ff8884a13ec0374.diff
LOG: [libc++] Explicitly enumerate std::string external instantiations.
The external instantiation of std::string is a problem for libc++.
Additions and removals of inline functions in string can cause ABI
breakages, including introducing new symbols.
This patch aims to:
(1) Make clear which functions are explicitly instatiated.
(2) Prevent new functions from being accidentally instantiated.
(3) Allow a migration path for adding or removing functions from the
explicit instantiation over time.
Although this new formulation is uglier, it is preferable from a
maintainability and readability standpoint because it explicitly
enumerates the functions we've chosen to expose in our ABI. Changing
this list is non-trivial and requires thought and planning.
(3) is achieved by making it possible to control the extern template declaration
separately from it's definition. Meaning we could add a new definition to
the dylib, wait for it to roll out, then add the extern template
declaration to the header. Similarly, we could remove existing extern
template declarations while still keeping the definition to prevent ABI
breakages.
Added:
Modified:
libcxx/include/__config
libcxx/include/__string
libcxx/include/string
libcxx/src/string.cpp
Removed:
################################################################################
diff --git a/libcxx/include/__config b/libcxx/include/__config
index 7394d443b729..1d6dd54eeb92 100644
--- a/libcxx/include/__config
+++ b/libcxx/include/__config
@@ -897,6 +897,10 @@ typedef unsigned int char32_t;
#define _LIBCPP_EXTERN_TEMPLATE2(...) extern template __VA_ARGS__;
#endif
+#ifndef _LIBCPP_EXTERN_TEMPLATE_DEFINE
+#define _LIBCPP_EXTERN_TEMPLATE_DEFINE(...) template __VA_ARGS__;
+#endif
+
#if defined(__APPLE__) || defined(__FreeBSD__) || defined(_LIBCPP_MSVCRT_LIKE) || \
defined(__sun__) || defined(__NetBSD__) || defined(__CloudABI__)
#define _LIBCPP_LOCALE__L_EXTENSIONS 1
diff --git a/libcxx/include/__string b/libcxx/include/__string
index 056b9b80ea50..1bbfbbacf959 100644
--- a/libcxx/include/__string
+++ b/libcxx/include/__string
@@ -70,6 +70,60 @@ _LIBCPP_PUSH_MACROS
_LIBCPP_BEGIN_NAMESPACE_STD
+// The the extern template ABI lists are kept outside of <string> to improve the
+// readability of that header.
+
+#define _LIBCPP_STRING_EXTERN_TEMPLATE_LIST(_Func, _CharType) \
+ _Func(_LIBCPP_FUNC_VIS basic_string<_CharType>& basic_string<_CharType>::replace(size_type, size_type, value_type const*, size_type)) \
+ _Func(_LIBCPP_FUNC_VIS basic_string<_CharType>::size_type basic_string<_CharType>::rfind(value_type const*, size_type, size_type) const) \
+ _Func(_LIBCPP_FUNC_VIS void basic_string<_CharType>::__init(value_type const*, size_type, size_type)) \
+ _Func(_LIBCPP_FUNC_VIS basic_string<_CharType>::basic_string(basic_string const&)) \
+ _Func(_LIBCPP_FUNC_VIS basic_string<_CharType>& basic_string<_CharType>::replace(size_type, size_type, value_type const*)) \
+ _Func(_LIBCPP_FUNC_VIS basic_string<_CharType>::basic_string(basic_string const&, std::allocator<_CharType> const&)) \
+ _Func(_LIBCPP_FUNC_VIS basic_string<_CharType>::size_type basic_string<_CharType>::find_last_not_of(value_type const*, size_type, size_type) const) \
+ _Func(_LIBCPP_FUNC_VIS basic_string<_CharType>::~basic_string()) \
+ _Func(_LIBCPP_FUNC_VIS basic_string<_CharType>::size_type basic_string<_CharType>::find_first_not_of(value_type const*, size_type, size_type) const) \
+ _Func(_LIBCPP_FUNC_VIS basic_string<_CharType>& basic_string<_CharType>::insert(size_type, size_type, value_type)) \
+ _Func(_LIBCPP_FUNC_VIS basic_string<_CharType>& basic_string<_CharType>::operator=(value_type)) \
+ _Func(_LIBCPP_FUNC_VIS void basic_string<_CharType>::__init(value_type const*, size_type)) \
+ _Func(_LIBCPP_FUNC_VIS const _CharType& basic_string<_CharType>::at(size_type) const) \
+ _Func(_LIBCPP_FUNC_VIS basic_string<_CharType>& basic_string<_CharType>::insert(size_type, value_type const*, size_type)) \
+ _Func(_LIBCPP_FUNC_VIS basic_string<_CharType>::size_type basic_string<_CharType>::find_first_of(value_type const*, size_type, size_type) const) \
+ _Func(_LIBCPP_FUNC_VIS basic_string<_CharType>& basic_string<_CharType>::replace(size_type, size_type, size_type, value_type)) \
+ _Func(_LIBCPP_FUNC_VIS basic_string<_CharType>& basic_string<_CharType>::assign(value_type const*, size_type)) \
+ _Func(_LIBCPP_FUNC_VIS void basic_string<_CharType>::reserve(size_type)) \
+ _Func(_LIBCPP_FUNC_VIS basic_string<_CharType>& basic_string<_CharType>::append(value_type const*, size_type)) \
+ _Func(_LIBCPP_FUNC_VIS basic_string<_CharType>& basic_string<_CharType>::assign(basic_string const&, size_type, size_type)) \
+ _Func(_LIBCPP_FUNC_VIS basic_string<_CharType>::size_type basic_string<_CharType>::copy(value_type*, size_type, size_type) const) \
+ _Func(_LIBCPP_FUNC_VIS basic_string<_CharType>::basic_string(basic_string const&, size_type, size_type, std::allocator<_CharType> const&)) \
+ _Func(_LIBCPP_FUNC_VIS basic_string<_CharType>::size_type basic_string<_CharType>::find(value_type, size_type) const) \
+ _Func(_LIBCPP_FUNC_VIS void basic_string<_CharType>::__init(size_type, value_type)) \
+ _Func(_LIBCPP_FUNC_VIS basic_string<_CharType>& basic_string<_CharType>::insert(size_type, value_type const*)) \
+ _Func(_LIBCPP_FUNC_VIS basic_string<_CharType>::size_type basic_string<_CharType>::find_last_of(value_type const*, size_type, size_type) const) \
+ _Func(_LIBCPP_FUNC_VIS void basic_string<_CharType>::__grow_by(size_type, size_type, size_type, size_type, size_type, size_type)) \
+ _Func(_LIBCPP_FUNC_VIS void basic_string<_CharType>::__grow_by_and_replace(size_type, size_type, size_type, size_type, size_type, size_type, value_type const*)) \
+ _Func(_LIBCPP_FUNC_VIS void basic_string<_CharType>::push_back(value_type)) \
+ _Func(_LIBCPP_FUNC_VIS basic_string<_CharType>& basic_string<_CharType>::append(size_type, value_type)) \
+ _Func(_LIBCPP_FUNC_VIS basic_string<_CharType>::size_type basic_string<_CharType>::rfind(value_type, size_type) const) \
+ _Func(_LIBCPP_FUNC_VIS basic_string<_CharType>::size_type basic_string<_CharType>::npos) \
+ _Func(_LIBCPP_FUNC_VIS basic_string<_CharType>& basic_string<_CharType>::assign(size_type, value_type)) \
+ _Func(_LIBCPP_FUNC_VIS basic_string<_CharType>& basic_string<_CharType>::erase(size_type, size_type)) \
+ _Func(_LIBCPP_FUNC_VIS basic_string<_CharType>& basic_string<_CharType>::append(basic_string const&, size_type, size_type)) \
+ _Func(_LIBCPP_FUNC_VIS int basic_string<_CharType>::compare(value_type const*) const) \
+ _Func(_LIBCPP_FUNC_VIS int basic_string<_CharType>::compare(size_type, size_type, value_type const*) const) \
+ _Func(_LIBCPP_FUNC_VIS _CharType& basic_string<_CharType>::at(size_type)) \
+ _Func(_LIBCPP_FUNC_VIS basic_string<_CharType>& basic_string<_CharType>::assign(value_type const*)) \
+ _Func(_LIBCPP_FUNC_VIS basic_string<_CharType>::size_type basic_string<_CharType>::find(value_type const*, size_type, size_type) const) \
+ _Func(_LIBCPP_FUNC_VIS int basic_string<_CharType>::compare(size_type, size_type, basic_string const&, size_type, size_type) const) \
+ _Func(_LIBCPP_FUNC_VIS int basic_string<_CharType>::compare(size_type, size_type, value_type const*, size_type) const) \
+ _Func(_LIBCPP_FUNC_VIS basic_string<_CharType>& basic_string<_CharType>::operator=(basic_string const&)) \
+ _Func(_LIBCPP_FUNC_VIS basic_string<_CharType>& basic_string<_CharType>::append(value_type const*)) \
+ _Func(_LIBCPP_FUNC_VIS basic_string<_CharType>& basic_string<_CharType>::replace(size_type, size_type, basic_string const&, size_type, size_type)) \
+ _Func(_LIBCPP_FUNC_VIS basic_string<_CharType>::iterator basic_string<_CharType>::insert(basic_string::const_iterator, value_type)) \
+ _Func(_LIBCPP_FUNC_VIS void basic_string<_CharType>::resize(size_type, value_type)) \
+ _Func(_LIBCPP_FUNC_VIS basic_string<_CharType>& basic_string<_CharType>::insert(size_type, basic_string const&, size_type, size_type))
+
+
// char_traits
template <class _CharT>
diff --git a/libcxx/include/string b/libcxx/include/string
index 8a0ac844470c..70093a89714e 100644
--- a/libcxx/include/string
+++ b/libcxx/include/string
@@ -1676,6 +1676,8 @@ basic_string(basic_string_view<_CharT, _Traits>, _Sz, _Sz, const _Allocator& = _
-> basic_string<_CharT, _Traits, _Allocator>;
#endif
+_LIBCPP_STRING_EXTERN_TEMPLATE_LIST(_LIBCPP_EXTERN_TEMPLATE, char)
+_LIBCPP_STRING_EXTERN_TEMPLATE_LIST(_LIBCPP_EXTERN_TEMPLATE, wchar_t)
template <class _CharT, class _Traits, class _Allocator>
inline
@@ -4330,8 +4332,6 @@ basic_string<_CharT, _Traits, _Allocator>::__subscriptable(const const_iterator*
#endif // _LIBCPP_DEBUG_LEVEL >= 2
-_LIBCPP_EXTERN_TEMPLATE(class _LIBCPP_EXTERN_TEMPLATE_TYPE_VIS basic_string<char>)
-_LIBCPP_EXTERN_TEMPLATE(class _LIBCPP_EXTERN_TEMPLATE_TYPE_VIS basic_string<wchar_t>)
#if _LIBCPP_STD_VER > 11
// Literal suffixes for basic_string [basic.string.literals]
diff --git a/libcxx/src/string.cpp b/libcxx/src/string.cpp
index 4802d63c811b..1e98c686cbcf 100644
--- a/libcxx/src/string.cpp
+++ b/libcxx/src/string.cpp
@@ -20,8 +20,8 @@ _LIBCPP_BEGIN_NAMESPACE_STD
template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS __basic_string_common<true>;
-template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS basic_string<char>;
-template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS basic_string<wchar_t>;
+_LIBCPP_STRING_EXTERN_TEMPLATE_LIST(_LIBCPP_EXTERN_TEMPLATE_DEFINE, char)
+_LIBCPP_STRING_EXTERN_TEMPLATE_LIST(_LIBCPP_EXTERN_TEMPLATE_DEFINE, wchar_t)
template
string
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