* Follow-up to removed restriction of pch naming on GCC
* Fix pch path conflict on GCC
gcc-pch-generator rewrites target name to a value derived from a header name
and this cases path conflict if multiple pch are created from the same header.
hello.cpp is duplicated in the test for the same reason but for `exe` target --
`exe hello-afx : hello.cpp ;` uses `hello.o` for object file name.
Adds gnu11 (libstdc++ with new ABI) and libc++ values to stdlib feature.
The value gnu was already in use by sun toolset, so this commit sets it as
libstdc++ with old ABI. Adds support for that feature to gcc, clang-linux and
clang-darwin toolsets. Refactors sun toolset to use stdlib feature via toolset
flags.
* add LTO support
Adds lto feature with 2 values: off (the default) and on. The feature
enables link-time optimizations. Also adds support for the feature to
gcc, clang and msvc toolsets.
* add docs for lto feature
* add lto-mode subfeature
* change lto-mode=full to be the default for uniform behaviour
* make lto feature optional
This adds a `b2::system_info` class to obtain available information on
system we are running in. Currently provides CPU counts.
And currently only implemented for macOS.
Changed the doc language to make Jamfile a possible root project. And
a clarification for when that happens. Also made some spelling fixes and
HTML style improvements.
local-visibility is intended to be used by libraries or targets that require
a particular visibility mode. It is not propagated to dependencies. It is
equivalent to the previous visibility feature.
The new visibility feature is a composite propagated feature, so it can be
specified by users and higher level targets as a requirement. This feature is
translated to local-visibility.
The new visibility feature can be used to specify default symbol visibility
on compilers and platforms that support it. The default visibility is
global, which matches most compilers' defaults. In gcc documentation it is
called the "default" visibility. Other modes are: protected and hidden.
