Akos Kiss d38ab71140 Improve the linking of libraries (#1338)
Although both jerry-libc and jerry-libm have configuration options
that enable/disable their build, in practice, only jerry-libc can be
replaced with the system (compiler-default) libc. If jerry-libm is
disabled, the build of jerry-main fails, as there is no way to
instruct the linker to link the system libm to the binary. (The
build system does have a way to pass flags to the linker, but those
flags are listed before the linked objects. For the references to
get resolved correctly, the libraries to be linked have to be
specified _after_ the objects.)

This patch adds the EXTERNAL_LINK_LIBS configuration option to
CMakeLists, which ensures that the specified libraries get
correctly passed to the linker. (E.g, replacing jerry-libm with
system libm becomes possible with
`JERRY_LIBM=OFF EXTERNAL_LINK_LIBS='-lm'`.)

Additionally, the patch also makes the following related changes:

* Removes the COMPILER_DEFAULT_LIBC configuration option, as it is
  (almost) always the opposite of JERRY_LIBC. Moreover, its name is
  misleading: its only role is to add `-nostdlib` to the linker
  flags.

* Makes use of transitive library dependencies: if a library has
  another library as dependency, and it is linked to a binary, its
  dependency is linked as well. Thus, jerry-libc, jerry-libm, and
  any external libraries are added to jerry-core as dependency, and
  then only jerry-core is linked to executables (cmake will take
  care of the rest).

* build.py and run-tests.py follow up the changes, along with some
  minor syntax changes.

* Moves static linking option to global CMakeLists, as unit test
  binaries should be linked the same way as jerry-main.

* Adds EXTERNAL_COMPILER_FLAGS and EXTERNAL_LINKER_FLAGS as last to
  the flag list, to allow user override of (nearly) anything.

The patch speculatively follows up the build system changes in the
mbed, riot-stm32f4, and zephyr targets.

JerryScript-DCO-1.0-Signed-off-by: Akos Kiss akiss@inf.u-szeged.hu
2016-09-15 13:07:01 +02:00
..
2016-06-30 14:35:23 +02:00
2016-08-26 13:20:07 +02:00
2016-08-26 13:20:07 +02:00
2016-09-01 14:32:31 +02:00