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In commit v3.4.0-rc1~18^2 (Disable shared library support when compiler
links statically, 2015-09-30) we tried to detect when the compiler is
not capable of linking shared libraries (possibly due to flags in use).
However, the approach is not robust against flags like `-nostdlib`.
Revert it for now pending another solution to the original problem.

When a user or a compiler wrapper adds '-static' to the compiler flags
then it will always link static binaries.  Detect this from the compiler
id binary and disable TARGET_SUPPORTS_SHARED_LIBS.  This will prevent
projects from accidentally adding shared libraries when the toolchain
does not support them.  It also helps CMake avoid linking with flags
that require shared libraries to be supported.

The documetnation of binutils:

  https://sourceware.org/binutils/docs/binutils/ar-cmdline.html

suggests to use the parameters "q" and "c" in this order ("q" is
operation, and "c" is the modifier).
Suggested-by: Дилян Палаузов <dilyan.palauzov@aegee.org>

Teach the Makefile and Ninja generators to substitute for an <INCLUDES>
placeholder instead of putting -I in <FLAGS>.  Update our values for

  CMAKE_<LANG>_COMPILE_OBJECT,
  CMAKE_<LANG>_CREATE_ASSEMBLY_SOURCE, and
  CMAKE_<LANG>_CREATE_PREPROCESSED_SOURCE

to place <INCLUDES> just before <FLAGS>.

Generalize the change from commit 39d0ade0 (Windows-GNU: Support
duplicate object names in large archives, 2014-04-14) to the default
archive rules.  These rules have used an incremental append approach
since commit v2.8.0~1856 (Build large archives incrementally,
2008-08-04).  Switch from "ar r" to "ar q" to be sure we always append
objects instead of replacing them.

s/defalut/default/
Reported-by: Stephan Tolksdorf <st@quanttec.com>

Use consistent capitalization and write all words out in the cache entry
descriptions.

Remove the platform-specific description from the cache entry help
strings for these variables.

Historically these were both added for the Makefile and Visual Studio
generators, respectively.  Later the VS generators started using the
CMAKE_MAKE_PROGRAM cache entry to find the IDE build tool, and the
CMAKE_BUILD_TOOL was simply set as an alias.

Fix the documentation to explain that CMAKE_MAKE_PROGRAM is the modern
variable and that CMAKE_BUILD_TOOL is the compatibility alias, not the
other way around.  Replace uses of CMAKE_BUILD_TOOL with
CMAKE_MAKE_PROGRAM in CMake-provided modules.  Nothing needs to lookup
CMAKE_BUILD_TOOL in the cache, so simply set it as a normal variable.

Even though this variable gets set to CMAKE_<LANG>_COMPILER-NOTFOUND when
the compiler is not found, CMake<LANG>Compiler.cmake gets removed by
cmGlobalGenerator::EnableLanguage so in try compiles the value is empty.
Quote references to the variable in

 Modules/CMake(C|CXX|Fortran)Information.cmake
 Modules/CMakeDetermineCompilerId.cmake

to avoid dropping arguments from commands that expect them.

Ancient versions of CMake required else(), endif(), and similar block
termination commands to have arguments matching the command starting the
block.  This is no longer the preferred style.

Run the following shell code:

for c in else endif endforeach endfunction endmacro endwhile; do
    echo 's/\b'"$c"'\(\s*\)(.\+)/'"$c"'\1()/'
done >convert.sed &&
git ls-files -z -- bootstrap '*.cmake' '*.cmake.in' '*CMakeLists.txt' |
egrep -z -v '^(Utilities/cm|Source/kwsys/)' |
egrep -z -v 'Tests/CMakeTests/While-Endwhile-' |
xargs -0 sed -i -f convert.sed &&
rm convert.sed

Ancient CMake versions required upper-case commands.  Later command
names became case-insensitive.  Now the preferred style is lower-case.

Run the following shell code:

cmake --help-command-list |
grep -v "cmake version" |
while read c; do
    echo 's/\b'"$(echo $c | tr '[:lower:]' '[:upper:]')"'\(\s*\)(/'"$c"'\1(/g'
done >convert.sed &&
git ls-files -z -- bootstrap '*.cmake' '*.cmake.in' '*CMakeLists.txt' |
egrep -z -v '^(Utilities/cm|Source/kwsys/)' |
xargs -0 sed -i -f convert.sed &&
rm convert.sed

Our Git commit hooks disallow modification or addition of lines with
trailing whitespace.  Wipe out all remnants of trailing whitespace
everywhere except third-party code.

Run the following shell code:

git ls-files -z -- \
 bootstrap doxygen.config '*.readme' \
 '*.c' '*.cmake' '*.cpp' '*.cxx' \
 '*.el' '*.f' '*.f90' '*.h' '*.in' '*.in.l' '*.java' \
 '*.mm' '*.pike' '*.py' '*.txt' '*.vim' |
egrep -z -v '^(Utilities/cm|Source/(kwsys|CursesDialog/form)/)' |
egrep -z -v '^(Modules/CPack\..*\.in)' |
xargs -0 sed -i 's/ \+$//'

Store in CMAKE_${lang}_COMPILE_OPTIONS_DLL flags from
CMAKE_SHARED_LIBRARY_${lang}_FLAGS that are truly exclusive to shared
libraries.

Store in new platform variables

  CMAKE_${lang}_COMPILE_OPTIONS_PIC
  CMAKE_${lang}_COMPILE_OPTIONS_PIE

flags for position independent code generation.

In almost all cases, this means duplication of the
CMAKE_SHARED_LIBRARY_${lang}_FLAGS for the _PIC case and using the
assumed pie equivalent for the _PIE case.  Note that the GNU compiler
has supported -fPIE since 3.4 and that there is no -fPIC on GNU for
Windows or Cygwin.

There is a possibility that the _PIE variables are not correct.
However, as there is no backwards compatibility to be concerned about
(as the POSITION_INDEPENDENT_CODE property is not used anywhere yet),
the current state suffices.

Add a boolean target property NO_SONAME which may be used to disable
soname for the specified shared library or module even if the platform
supports it.  This property should be useful for private shared
libraries or various plugins which live in private directories and have
not been designed to be found or loaded globally.

Replace references to <CMAKE_SHARED_LIBRARY_SONAME_${LANG}_FLAG> and
hard-coded -install_name flags with a conditional <SONAME_FLAG> which is
expanded to the value of the CMAKE_SHARED_LIBRARY_SONAME_${LANG}_FLAG
definition as long as soname supports is enabled for the target in
question.  Keep expanding CMAKE_SHARED_LIBRARY_SONAME_${LANG}_FLAG in
rules in case third party projects still use it.  Such projects would
not yet use NO_SONAME so the adjacent <TARGET_SONAME> will always be
expanded.  Make <TARGET_INSTALLNAME_DIR> NO_SONAME aware as well.  Since
-install_name is soname on OS X, this should not be a problem if this
variable is expanded only if soname is enabled.

The Ninja generator performs rule variable substitution only once
globally per rule to put its own placeholders.  Final substitution is
performed by ninja at build time.  Therefore we cannot conditionally
replace the soname placeholders on a per-target basis.  Rather than
omitting $SONAME from rules.ninja, simply do not write its contents for
targets which have NO_SONAME.  Since 3 variables are affected by
NO_SONAME ($SONAME, $SONAME_FLAG, $INSTALLNAME_DIR), set them only if
soname is enabled.

If CXX or Fortran is enabled before C then the values of

  CMAKE_SHARED_MODULE_C_FLAGS
  CMAKE_SHARED_MODULE_CREATE_C_FLAGS

may not be available.  On platforms where MODULE library (plugin) creation
is the same as SHARED library creation initialize the MODULE creation
flags from the SHARED creation flags of the matching language instead of
assuming that C has been enabled first.

Teach the COnly and CxxOnly tests to build MODULE libraries.  The latter
covers this specific case.

Load platform files named in CMAKE_<lang>_ABI_FILES for each language
once the ABI sizeof(void*) is known.  During the first configuration
this is after the test for working compiler and ABI detection checks.
During later configurations the ABI information is immediately available
because it has been saved in CMake<lang>Compiler.cmake.

In commit 295b5b60 (Honor CMAKE_USER_MAKE_RULES_OVERRIDE in try_compile,
2010-06-29) we started passing the value of this variable when building
a try_compile project.  If the variable contains a relative path it must
be treated with respect to the file where it is first used.  Ensure that
the value is converted to a full path so that it is correctly referenced
in the try_compile projects.

Commit aaa88d33 (Build large archives incrementally, 2008-08-04)
hard-coded rules to create static archives incrementally in each
language information file.  Set each rule conditionally to allow
compiler and platform information files to override the language
default rules.
Inspired-by: Harald Pohl <pohl.h@eppendorf.de>

In each CMake<lang>Information.cmake file we use an _INCLUDED_FILE
variable to track whether a compiler information file has been loaded.
Reset this variable for each language.

This fixes Fortran under VS generators with the Intel plugin.
Previously the variable would be left set true from C and C++ and then
Fortran would not load old-style files like Platform/Windows-ifort.

Several platform-wide linker flag variables are defined in
Modules/Platform/<os>.cmake files for C and then copied by the
Modules/CMake<lang>Information.cmake file for each language.
We now use this approach for the variables

  CMAKE_EXE_EXPORTS_${lang}_FLAG
  CMAKE_SHARED_LIBRARY_SONAME_${lang}_FLAG
  CMAKE_SHARED_LIBRARY_CREATE_${lang}_FLAGS

to avoid duplication for multiple languages in each platform file.

This platform configuration variable is unused.  Modules are built using
the value of CMAKE_SHARED_LIBRARY_RUNTIME_${lang}_FLAG.

The commit "fix for bug 4772" added a work-around to CMakeCInformation
for platform config files that put compiler information in the system
file (like SunOS flags for GCC).  This commit adds the same work-around
for CXX and Fortran.  It is necessary to support enabling these
languages separately from C in other subdirectories.

The commit "Avoid (Unix|Windows)Paths.cmake multiple include" added
include blockers that prevent the files from multiple inclusion, so it
is safe to include the system information files from every language.

See issue #4772 and issue #9656.

This adds copyright/license notification blocks CMake's non-find
modules.  Most of the modules had no notices at all.  Some had notices
referring to the BSD license already.  This commit normalizes existing
notices and adds missing notices.

This teaches the language configuration modules to load per-compiler
information for each language using the compiler id but no system name.
They look for modules named "Compiler/<id>-<lang>.cmake".  Such modules
may specify compiler flags that do not depend on the platform.

ENH: fix problem where rc language recursively included itself because CMAKE_BASE_NAME was used from c compiler, do the same fix for other uses of CMAKE_BASE_NAME

Creation of archive libraries with the unix 'ar' tool should be done
incrementally when the number of object files is large.  This avoids
problems with the command line getting too many arguments.

  - Move runtime path ordering out of cmComputeLinkInformation
    into its own class cmOrderRuntimeDirectories.
  - Create an instance of cmOrderRuntimeDirectories for runtime
    path ordering and another instance for dependent library
    path ordering.
  - Replace CMAKE_DEPENDENT_SHARED_LIBRARY_MODE with explicit
    CMAKE_LINK_DEPENDENT_LIBRARY_FILES boolean.
  - Create CMAKE_LINK_DEPENDENT_LIBRARY_DIRS boolean.
  - Create variables to specify -rpath-link flags:
      CMAKE_SHARED_LIBRARY_RPATH_LINK_<LANG>_FLAG
      CMAKE_EXECUTABLE_RPATH_LINK_<LANG>_FLAG
  - Enable -rpath-link flag on Linux and QNX.
  - Documentation and error message updates

BUG: CMAKE_EXECUTABLE_RUNTIME_CXX_FLAG should get its default value from CMAKE_SHARED_LIBRARY_RUNTIME_CXX_FLAG, not CMAKE_SHARED_LIBRARY_RUNTIME_C_FLAG.

  - This is purely an implementation improvement.  No interface has changed.
  - Create cmComputeLinkInformation class
  - Move and re-implement logic from:
      cmLocalGenerator::ComputeLinkInformation
      cmOrderLinkDirectories
  - Link libraries to targets with their full path (if it is known)
  - Dirs specified with link_directories command still added with -L
  - Make link type specific to library names without paths
    (name libfoo.a without path becomes -Wl,-Bstatic -lfoo)
  - Make directory ordering specific to a runtime path computation feature
    (look for conflicting SONAMEs instead of library names)
  - Implement proper rpath support on HP-UX and AIX.

ENH: Create COMPILE_DEFINITIONS property for targets and source files.  Create <config>_COMPILE_DEFINITIONS property as per-configuration version.  Add Preprocess test to test the feature.  Document limitations on Xcode and VS6 generators.

ENH: remove support for presetting CMAKE_SYSTEM_INFO_FILE,
CMAKE_SYSTEM_AND_C_COMPILER_INFO_FILE, CMAKE_SYSTEM_AND_CXX_COMPILER_INFO_FILE,
CMAKE_SYSTEM_AND_C_COMPILER_AND_PROCESSOR_INFO_FILE and CMAKE_SYSTEM_AND_CXX_COMPILER_AND_PROCESSOR_INFO_FILE

Instead of presetting these variables to arbitrary filenames, users should
set up CMAKE_SYSTEM_NAME and the compilers correctly and also create a
Platform/ directory so these files will all follow the official cmake style,
which should make it easier to understand and debug project which have their
own platform/toolchain support files.

-remove support for a suffix to MS crosscompilers, since this is not (yet)
supported by cmake and might confuse users

Alex