Add a check that a simple source file can compile as C++17 that uses
some of the features we need.  Do this only when hosted by CMake 3.8
or above because those versions are aware of C++17.

Check for unordered_map as we do in bootstrap since commit 375eca78
(bootstrap: Check support for unordered_map from compiler mode,
2017-11-30).  Also maintain the existing C++14 cstdio check.

The check for C++14 and cstdio is a special case of the more general
problem of checking that the compiler's C++14 mode supports everything
we need.  Rename the checks accordingly.

It was deprecated by C++11 and removed by C++17.  Use a C++11 lambda.

With the Ninja generator we may invoke `cmake_symlink_library` with
different slash conventions (`/` versus `\`) for different arguments.
Fix comparison of the paths/names given to tolerate this.

Fixes: #17579

Sebastian Holtermann authored Dec 18, 2017 and Brad King committed Dec 20, 2017

In the AutogenInfo.cmake file the separator for nested lists was
`@LSEP@` which led to a speed regression because the `@` character
triggered an (unsuccessful) expression evaluation.

By setting the policy version of the CMake instance in the
`_autogen` target to 3.9, the OLD `@` evaluating behavior
controlled by policy CMP0053 is disabled.

Also the nested lists separator string is changed to `<<<S>>>`,
which solves the problem twofold.

Issue: #17570

"single" is a type declared in /usr/include/floatingpoint.h on Solaris,
so the local variable of the same name in cmParseArgumentsCommand.cxx
was triggering a compiler warning about the local variable shadowing
the type.

In the AutogenInfo.cmake file the separator for nested lists
was `@LSEP@` which led to a speed regression because the `@`
character triggered an (unsuccessful) expression evaluation.

By setting the policy version of the CMake instance in the
`_autogen` target to 3.9, the OLD `@` evaluating behavior
controlled by policy CMP0053 is disabled.

Also the nested lists separator string is changed to `<<<S>>>`,
which solves the problem twofold.

Closes #17570

The corresponding 'virtual' removed.

Added support for QT IFW "RemoveTargetDir" boolean option.  QTIFW
supports an option to prevent, or not, deletion of the installation
directory. This is a direct pass-through to that variable.

Robert Maynard authored Dec 13, 2017 and Brad King committed Dec 15, 2017

When C++ features require a certain C++/CUDA level, verify or update the
standard level target property for each language independently.

While at it, add missing rejection of invalid `CUDA_STANDARD` property
values.

Co-Author: Brad King <brad.king@kitware.com>
Fixes: #17519

Robert Maynard authored Dec 13, 2017 and Brad King committed Dec 15, 2017

The original code doesn't scale well as we add support for each new
language level.

Co-Author: Brad King <brad.king@kitware.com>

Vitaly Stakhovsky authored Dec 13, 2017 and Brad King committed Dec 14, 2017

Match the XML preamble generated by VS 2010 and later.

Yurii Batrak authored Dec 05, 2017 and Brad King committed Dec 14, 2017

The 'requires' step was used to provide implicit dependencies between
the generated Fortran module files and a Fortran target that needs these
module files to ensure the correct compilation order.  After recent
refactoring to resolve all dependencies explicitly through `.mod.stamp`
make targets, the separate 'requires' step is not needed anymore.

Yurii Batrak authored Nov 24, 2017 and Brad King committed Dec 14, 2017

Makefiles generated by cmake use a series of nested calls to build
`*.provides.build` targets that are used when the 'requires' step is
needed.  That leads to significant degradation of the build time for
incremental builds.  Re-arrange dependencies to eliminate the nested
calls.

Explicit `.mod.stamp` targets introduced by this commit could lead to
situation when a stamp file always older than its dependency.  This
happens during the incremental build when building of an updated Fortran
source produces a module file that has no differences from the stored
stamp file.  In such case `cmake_copy_f90_mod` will be triggered on each
new build to compare a module file with the corresponding stamp file.
This behavior is expected and can not be changed without nested calls
that slow down the build.  The copy-if-different check is much cheaper
than an entire nested make call.

Joel Frederico authored Dec 08, 2017 and Brad King committed Dec 14, 2017

Generating graphs of dependencies now uses interface targets, but graphs
of dependers did not include interface targets.

Fixes: #17542