Possible regressions under g++ 4.4 and clang++ 3.4 when building quickbook

[pdimov]

g++ 4.4:

gcc.compile.c++ ../../../bin.v2/tools/quickbook/test/quickbook_manual-1_4.test2/gcc-4.4.7/debug/cxxstd-0x-iso/link-static/text_diff.o
In file included from ../../../boost/move/traits.hpp:31,
                 from ../../../boost/move/utility.hpp:30,
                 from ../../../boost/optional/optional.hpp:53,
                 from ../../../boost/optional.hpp:15,
                 from ../../../boost/spirit/home/classic/core/match.hpp:15,
                 from ../../../boost/spirit/home/classic/core/scanner/scanner.hpp:14,
                 from ../../../boost/spirit/home/classic/core/parser.hpp:14,
                 from ../../../boost/spirit/home/classic/core/primitives/primitives.hpp:15,
                 from ../../../boost/spirit/include/classic_primitives.hpp:11,
                 from /home/travis/boost/tools/quickbook/test/src/text_diff.cpp:15:
../../../boost/move/detail/type_traits.hpp:306: error: a function call cannot appear in a constant-expression
../../../boost/move/detail/type_traits.hpp:306: error: an assignment cannot appear in a constant-expression
../../../boost/move/detail/type_traits.hpp:306: error: a function call cannot appear in a constant-expression
../../../boost/move/detail/type_traits.hpp:318: error: a function call cannot appear in a constant-expression
../../../boost/move/detail/type_traits.hpp:318: error: a function call cannot appear in a constant-expression

https://travis-ci.org/github/boostorg/quickbook/jobs/752114232

clang++ 3.4:

clang-linux.compile.c++.without-pch ../../../bin.v2/tools/quickbook/test/quickbook_manual-1_4.test2/clang-linux-3.4.2/debug/cxxstd-0x-iso/link-static/text_diff.o
In file included from /home/travis/boost/tools/quickbook/test/src/text_diff.cpp:15:
In file included from ../../../boost/spirit/include/classic_primitives.hpp:11:
In file included from ../../../boost/spirit/home/classic/core/primitives/primitives.hpp:15:
In file included from ../../../boost/spirit/home/classic/core/parser.hpp:14:
In file included from ../../../boost/spirit/home/classic/core/scanner/scanner.hpp:14:
In file included from ../../../boost/spirit/home/classic/core/match.hpp:15:
In file included from ../../../boost/optional.hpp:15:
In file included from ../../../boost/optional/optional.hpp:53:
In file included from ../../../boost/move/utility.hpp:30:
In file included from ../../../boost/move/traits.hpp:31:
../../../boost/move/detail/type_traits.hpp:117:10: error: builtin feature check macro requires a parenthesized identifier
#   elif __has_extension
         ^
../../../boost/move/detail/type_traits.hpp:117:25: error: expected value in expression
#   elif __has_extension
                        ^
<scratch space>:181:1: note: expanded from here
0
^
2 errors generated.

https://travis-ci.org/github/boostorg/quickbook/jobs/752114234

I'm not sure whether we need to care about these old compilers, but the Quickbook travis has them, so it fails.

[pdimov]

Also breaks the Function tests, https://travis-ci.org/github/boostorg/function/builds/752126595

Same comment as above - we could, in principle, declare these as unsupported, if it's too much of a bother. Although the Clang error looks legit.

[igaztanaga]

Looks like Quickbook tests with Clang 3.4 are now ok:

https://travis-ci.org/github/boostorg/quickbook/jobs/767312070

so I'm closing the issue.