LCC: Add dedicated support for MCST LCC compiler

Divert LCC compiler as a new one, instead of treating it as GNU.

Since old times, Elbrus C/C++/Fortran Compiler (LCC) by MCST has been
passing checks for GNU compilers, so it has been identified as GNU.
Now, with intent of seriously upstreaming its support, it has been
added as a separate LCC compiler, and its version displays not a
supported GCC version, but LCC version itself (e.g. LCC 1.25.19 instead
of GNU 7.3.0).

This commit adds its support for detection, and also converts basically
every check like 'is this compiler GNU?' to 'is this compiler GNU or
LCC?'. The only places where this check is untouched, is where it
regards other platforms where LCC is unavailable (primarily non-Linux),
and where it REALLY differs from GNU compiler.

Note: this transition may break software that are already ported to
Elbrus, but hardly relies that LCC will be detected as GNU; still such
software is not known.

1 files changed, 109 insertions, 0 deletions

diff --git a/Modules/Compiler/LCC-CXX-FeatureTests.cmake b/Modules/Compiler/LCC-CXX-FeatureTests.cmake
new file mode 100644
index 0000000..45c5470
--- /dev/null
+++ b/Modules/Compiler/LCC-CXX-FeatureTests.cmake
@@ -0,0 +1,109 @@
+
+# Reference: http://gcc.gnu.org/projects/cxx0x.html
+# http://gcc.gnu.org/projects/cxx1y.html
+
+set(_cmake_oldestSupported "(__GNUC__ * 100 + __GNUC_MINOR__) >= 404")
+
+set(GNU50_CXX14 "(__GNUC__ * 100 + __GNUC_MINOR__) >= 500 && __cplusplus >= 201402L")
+set(_cmake_feature_test_cxx_variable_templates "${GNU50_CXX14}")
+set(_cmake_feature_test_cxx_relaxed_constexpr "${GNU50_CXX14}")
+set(_cmake_feature_test_cxx_aggregate_default_initializers "${GNU50_CXX14}")
+
+# GNU 4.9 in c++14 mode sets __cplusplus to 201300L, so don't test for the
+# correct value of it below.
+# https://patchwork.ozlabs.org/patch/382470/
+set(GNU49_CXX14 "(__GNUC__ * 100 + __GNUC_MINOR__) >= 409 && __cplusplus > 201103L")
+set(_cmake_feature_test_cxx_contextual_conversions "${GNU49_CXX14}")
+set(_cmake_feature_test_cxx_attribute_deprecated "${GNU49_CXX14}")
+set(_cmake_feature_test_cxx_decltype_auto "${GNU49_CXX14}")
+set(_cmake_feature_test_cxx_digit_separators "${GNU49_CXX14}")
+set(_cmake_feature_test_cxx_generic_lambdas "${GNU49_CXX14}")
+# GNU 4.3 supports binary literals as an extension, but may warn about
+# use of extensions prior to GNU 4.9
+# http://stackoverflow.com/questions/16334024/difference-between-gcc-binary-literals-and-c14-ones
+set(_cmake_feature_test_cxx_binary_literals "${GNU49_CXX14}")
+# The features below are documented as available in GNU 4.8 (by implementing an
+# earlier draft of the standard paper), but that version of the compiler
+# does not set __cplusplus to a value greater than 201103L until GNU 4.9:
+# http://gcc.gnu.org/onlinedocs/gcc-4.8.2/cpp/Standard-Predefined-Macros.html#Standard-Predefined-Macros
+# http://gcc.gnu.org/onlinedocs/gcc-4.9.0/cpp/Standard-Predefined-Macros.html#Standard-Predefined-Macros
+# So, CMake only reports availability for it with GNU 4.9 or later.
+set(_cmake_feature_test_cxx_return_type_deduction "${GNU49_CXX14}")
+set(_cmake_feature_test_cxx_lambda_init_captures "${GNU49_CXX14}")
+
+# Introduced in GCC 4.8.1
+set(GNU481_CXX11 "((__GNUC__ * 10000 + __GNUC_MINOR__ * 100 + __GNUC_PATCHLEVEL__) >= 40801) && __cplusplus >= 201103L")
+set(_cmake_feature_test_cxx_decltype_incomplete_return_types "${GNU481_CXX11}")
+set(_cmake_feature_test_cxx_reference_qualified_functions "${GNU481_CXX11}")
+set(GNU48_CXX11 "(__GNUC__ * 100 + __GNUC_MINOR__) >= 408 && __cplusplus >= 201103L")
+set(_cmake_feature_test_cxx_alignas "${GNU48_CXX11}")
+# The alignof feature works with GNU 4.7 and -std=c++11, but it is documented
+# as available with GNU 4.8, so treat that as true.
+set(_cmake_feature_test_cxx_alignof "${GNU48_CXX11}")
+set(_cmake_feature_test_cxx_attributes "${GNU48_CXX11}")
+set(_cmake_feature_test_cxx_inheriting_constructors "${GNU48_CXX11}")
+set(_cmake_feature_test_cxx_thread_local "${GNU48_CXX11}")
+set(GNU47_CXX11 "(__GNUC__ * 100 + __GNUC_MINOR__) >= 407 && __cplusplus >= 201103L")
+set(_cmake_feature_test_cxx_alias_templates "${GNU47_CXX11}")
+set(_cmake_feature_test_cxx_delegating_constructors "${GNU47_CXX11}")
+set(_cmake_feature_test_cxx_extended_friend_declarations "${GNU47_CXX11}")
+set(_cmake_feature_test_cxx_final "${GNU47_CXX11}")
+set(_cmake_feature_test_cxx_nonstatic_member_init "${GNU47_CXX11}")
+set(_cmake_feature_test_cxx_override "${GNU47_CXX11}")
+set(_cmake_feature_test_cxx_user_literals "${GNU47_CXX11}")
+# NOTE: C++11 was ratified in September 2011. GNU 4.7 is the first minor
+# release following that (March 2012), and the first minor release to
+# support -std=c++11. Prior to that, support for C++11 features is technically
+# experiemental and possibly incomplete (see for example the note below about
+# cxx_variadic_template_template_parameters)
+# GNU does not define __cplusplus correctly before version 4.7.
+# https://gcc.gnu.org/bugzilla/show_bug.cgi?id=1773
+# __GXX_EXPERIMENTAL_CXX0X__ is defined in prior versions, but may not be
+# defined in the future.
+set(GNU_CXX0X_DEFINED "(__cplusplus >= 201103L || (defined(__GXX_EXPERIMENTAL_CXX0X__) && __GXX_EXPERIMENTAL_CXX0X__))")
+set(GNU46_CXX11 "(__GNUC__ * 100 + __GNUC_MINOR__) >= 406 && ${GNU_CXX0X_DEFINED}")
+set(_cmake_feature_test_cxx_constexpr "${GNU46_CXX11}")
+set(_cmake_feature_test_cxx_defaulted_move_initializers "${GNU46_CXX11}")
+set(_cmake_feature_test_cxx_enum_forward_declarations "${GNU46_CXX11}")
+set(_cmake_feature_test_cxx_noexcept "${GNU46_CXX11}")
+set(_cmake_feature_test_cxx_nullptr "${GNU46_CXX11}")
+set(_cmake_feature_test_cxx_range_for "${GNU46_CXX11}")
+set(_cmake_feature_test_cxx_unrestricted_unions "${GNU46_CXX11}")
+set(GNU45_CXX11 "(__GNUC__ * 100 + __GNUC_MINOR__) >= 405 && ${GNU_CXX0X_DEFINED}")
+set(_cmake_feature_test_cxx_explicit_conversions "${GNU45_CXX11}")
+set(_cmake_feature_test_cxx_lambdas "${GNU45_CXX11}")
+set(_cmake_feature_test_cxx_local_type_template_args "${GNU45_CXX11}")
+set(_cmake_feature_test_cxx_raw_string_literals "${GNU45_CXX11}")
+set(GNU44_CXX11 "(__GNUC__ * 100 + __GNUC_MINOR__) >= 404 && ${GNU_CXX0X_DEFINED}")
+set(_cmake_feature_test_cxx_auto_type "${GNU44_CXX11}")
+set(_cmake_feature_test_cxx_defaulted_functions "${GNU44_CXX11}")
+set(_cmake_feature_test_cxx_deleted_functions "${GNU44_CXX11}")
+set(_cmake_feature_test_cxx_generalized_initializers "${GNU44_CXX11}")
+set(_cmake_feature_test_cxx_inline_namespaces "${GNU44_CXX11}")
+set(_cmake_feature_test_cxx_sizeof_member "${GNU44_CXX11}")
+set(_cmake_feature_test_cxx_strong_enums "${GNU44_CXX11}")
+set(_cmake_feature_test_cxx_trailing_return_types "${GNU44_CXX11}")
+set(_cmake_feature_test_cxx_unicode_literals "${GNU44_CXX11}")
+set(_cmake_feature_test_cxx_uniform_initialization "${GNU44_CXX11}")
+set(_cmake_feature_test_cxx_variadic_templates "${GNU44_CXX11}")
+# TODO: If features are ever recorded for GNU 4.3, there should possibly
+# be a new feature added like cxx_variadic_template_template_parameters,
+# which is implemented by GNU 4.4, but not 4.3. cxx_variadic_templates is
+# actually implemented by GNU 4.3, but variadic template template parameters
+# 'completes' it, so that is the version we record as having the variadic
+# templates capability in CMake. See
+# http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2008/n2555.pdf
+# TODO: Should be supported by GNU 4.3
+set(GNU43_CXX11 "${_cmake_oldestSupported} && ${GNU_CXX0X_DEFINED}")
+set(_cmake_feature_test_cxx_decltype "${GNU43_CXX11}")
+set(_cmake_feature_test_cxx_default_function_template_args "${GNU43_CXX11}")
+set(_cmake_feature_test_cxx_long_long_type "${GNU43_CXX11}")
+set(_cmake_feature_test_cxx_right_angle_brackets "${GNU43_CXX11}")
+set(_cmake_feature_test_cxx_rvalue_references "${GNU43_CXX11}")
+set(_cmake_feature_test_cxx_static_assert "${GNU43_CXX11}")
+# TODO: Should be supported since GNU 3.4?
+set(_cmake_feature_test_cxx_extern_templates "${_cmake_oldestSupported} && ${GNU_CXX0X_DEFINED}")
+# TODO: Should be supported forever?
+set(_cmake_feature_test_cxx_func_identifier "${_cmake_oldestSupported} && ${GNU_CXX0X_DEFINED}")
+set(_cmake_feature_test_cxx_variadic_macros "${_cmake_oldestSupported} && ${GNU_CXX0X_DEFINED}")
+set(_cmake_feature_test_cxx_template_template_parameters "${_cmake_oldestSupported} && __cplusplus")