asm: Add sx extension

docs: gcc https://gcc.gnu.org/onlinedocs/gcc/Overall-Options.html
      scons: https://scons.org/doc/3.0.5/HTML/scons-user/apb.html

  .S      Windows:  assembly language file
          ARM: CodeSourcery Sourcery Lite
  .sx     assembly language file + C pre-processor
          POSIX:  assembly language file + C pre-processor

mesonbuild/compilers/compilers.py

@@ -77,7 +77,7 @@ all_languages = lang_suffixes.keys()
 c_cpp_suffixes = {'h'}
 cpp_suffixes = set(lang_suffixes['cpp']) | c_cpp_suffixes
 c_suffixes = set(lang_suffixes['c']) | c_cpp_suffixes
-assembler_suffixes = {'s', 'S', 'asm', 'masm'}
+assembler_suffixes = {'s', 'S', 'sx', 'asm', 'masm'}
 llvm_ir_suffixes = {'ll'}
 all_suffixes = set(itertools.chain(*lang_suffixes.values(), assembler_suffixes, llvm_ir_suffixes, c_cpp_suffixes))
 source_suffixes = all_suffixes - header_suffixes

mesonbuild/compilers/mixins/arm.py

@@ -90,6 +90,7 @@ class ArmCompiler(Compiler):
                           'everything': default_warn_args + []}  # type: T.Dict[str, T.List[str]]
         # Assembly
         self.can_compile_suffixes.add('s')
+        self.can_compile_suffixes.add('sx')
 
     def get_pic_args(self) -> T.List[str]:
         # FIXME: Add /ropi, /rwpi, /fpic etc. qualifiers to --apcs
@@ -161,6 +162,7 @@ class ArmclangCompiler(Compiler):
              'b_ndebug', 'b_staticpic', 'b_colorout']}
         # Assembly
         self.can_compile_suffixes.add('s')
+        self.can_compile_suffixes.add('sx')
 
     def get_pic_args(self) -> T.List[str]:
         # PIC support is not enabled by default for ARM,

mesonbuild/compilers/mixins/compcert.py

@@ -68,6 +68,7 @@ class CompCertCompiler(Compiler):
     def __init__(self) -> None:
         # Assembly
         self.can_compile_suffixes.add('s')
+        self.can_compile_suffixes.add('sx')
         default_warn_args = []  # type: T.List[str]
         self.warn_args = {'0': [],
                           '1': default_warn_args,

mesonbuild/compilers/mixins/gnu.py

@@ -389,6 +389,7 @@ class GnuLikeCompiler(Compiler, metaclass=abc.ABCMeta):
             self.base_options.add(OptionKey('b_sanitize'))
         # All GCC-like backends can do assembly
         self.can_compile_suffixes.add('s')
+        self.can_compile_suffixes.add('sx')
 
     def get_pic_args(self) -> T.List[str]:
         if self.info.is_windows() or self.info.is_cygwin() or self.info.is_darwin():

mesonbuild/compilers/mixins/visualstudio.py

@@ -469,6 +469,7 @@ class ClangClCompiler(VisualStudioLikeCompiler):
 
         # Assembly
         self.can_compile_suffixes.add('s')
+        self.can_compile_suffixes.add('sx')
 
     def has_arguments(self, args: T.List[str], env: 'Environment', code: str, mode: str) -> T.Tuple[bool, bool]:
         if mode != 'link':

mesonbuild/compilers/mixins/xc16.py

@@ -65,6 +65,7 @@ class Xc16Compiler(Compiler):
             raise EnvironmentException('xc16 supports only cross-compilation.')
         # Assembly
         self.can_compile_suffixes.add('s')
+        self.can_compile_suffixes.add('sx')
         default_warn_args = []  # type: T.List[str]
         self.warn_args = {'0': [],
                           '1': default_warn_args,