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libstdc++: Improvements to standard error category objects (part deux) 

In r12-3860 the error categories in <system_error> were made final and
immortal, but I missed the categories for <future> and <ios>. This makes
the same changes to those.

libstdc++-v3/ChangeLog:

	* src/c++11/cxx11-ios_failure.cc (io_error_category): Define
	class and virtual functions as 'final'.
	(io_category_instance): Use constinit union to make the object
	immortal.
	* src/c++11/future.cc (future_error_category): Define class and
	virtual functions as 'final'.
	(future_category_instance): Use constinit union.
This commit is contained in:
Jonathan Wakely 2021-09-22 13:56:21 +01:00
parent 1918067e2d
commit 096228d84e
2 changed files with 31 additions and 20 deletions
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25
libstdc++-v3/src/c++11/cxx11-ios_failure.cc
View File

@ -44,14 +44,15 @@
namespace namespace
{ {
struct io_error_category : std::error_category struct io_error_category final : std::error_category
{ {
virtual const char* const char*
name() const noexcept name() const noexcept final
{ return "iostream"; } { return "iostream"; }
_GLIBCXX_DEFAULT_ABI_TAG _GLIBCXX_DEFAULT_ABI_TAG
virtual std::string message(int __ec) const std::string
message(int __ec) const final
{ {
std::string __msg; std::string __msg;
switch (std::io_errc(__ec)) switch (std::io_errc(__ec))
@ -67,13 +68,17 @@ namespace
} }
}; };
const io_error_category& struct constant_init
__io_category_instance() noexcept
{ {
static const io_error_category __ec{}; union {
return __ec; unsigned char unused;
} io_error_category cat;
};
constexpr constant_init() : cat() { }
~constant_init() { /* do nothing, union member is not destroyed */ }
};
__constinit constant_init io_category_instance{};
} // namespace } // namespace
namespace std _GLIBCXX_VISIBILITY(default) namespace std _GLIBCXX_VISIBILITY(default)
@ -82,7 +87,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
const error_category& const error_category&
iostream_category() noexcept iostream_category() noexcept
{ return __io_category_instance(); } { return io_category_instance.cat; }
ios_base::failure::failure(const string& __str) ios_base::failure::failure(const string& __str)
: system_error(io_errc::stream, __str) { } : system_error(io_errc::stream, __str) { }

26
libstdc++-v3/src/c++11/future.cc
View File

@ -27,14 +27,15 @@
namespace namespace
{ {
struct future_error_category : public std::error_category struct future_error_category final : public std::error_category
{ {
virtual const char* const char*
name() const noexcept name() const noexcept final
{ return "future"; } { return "future"; }
_GLIBCXX_DEFAULT_ABI_TAG _GLIBCXX_DEFAULT_ABI_TAG
virtual std::string message(int __ec) const std::string
message(int __ec) const final
{ {
std::string __msg; std::string __msg;
switch (std::future_errc(__ec)) switch (std::future_errc(__ec))
@ -59,12 +60,17 @@ namespace
} }
}; };
const future_error_category& struct constant_init
__future_category_instance() noexcept
{ {
static const future_error_category __fec{}; union {
return __fec; unsigned char unused;
} future_error_category cat;
};
constexpr constant_init() : cat() { }
~constant_init() { /* do nothing, union member is not destroyed */ }
};
__constinit constant_init future_category_instance{};
} }
namespace std _GLIBCXX_VISIBILITY(default) namespace std _GLIBCXX_VISIBILITY(default)
@ -76,7 +82,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
{ _GLIBCXX_THROW_OR_ABORT(future_error(make_error_code(future_errc(__i)))); } { _GLIBCXX_THROW_OR_ABORT(future_error(make_error_code(future_errc(__i)))); }
const error_category& future_category() noexcept const error_category& future_category() noexcept
{ return __future_category_instance(); } { return future_category_instance.cat; }
future_error::~future_error() noexcept { } future_error::~future_error() noexcept { }