Compilers: Add a preprocessor mode for clike compilers

A compiler object can now return a list of "modes", they are new
compiler object specialized for a specific task.

mesonbuild/backend/ninjabackend.py

@@ -1983,7 +1983,7 @@ class NinjaBackend(backends.Backend):
 
     @classmethod
     def compiler_to_rule_name(cls, compiler: Compiler) -> str:
-        return cls.get_compiler_rule_name(compiler.get_language(), compiler.for_machine)
+        return cls.get_compiler_rule_name(compiler.get_language(), compiler.for_machine, compiler.mode)
 
     @classmethod
     def compiler_to_pch_rule_name(cls, compiler: Compiler) -> str:
@@ -2362,6 +2362,8 @@ https://gcc.gnu.org/bugzilla/show_bug.cgi?id=47485'''))
                     self.generate_llvm_ir_compile_rule(compiler)
                 self.generate_compile_rule_for(langname, compiler)
                 self.generate_pch_rule_for(langname, compiler)
+                for mode in compiler.get_modes():
+                    self.generate_compile_rule_for(langname, mode)
 
     def generate_generator_list_rules(self, target):
         # CustomTargets have already written their rules and

mesonbuild/compilers/compilers.py

@@ -494,6 +494,7 @@ class Compiler(HoldableObject, metaclass=abc.ABCMeta):
     language: str
     id: str
     warn_args: T.Dict[str, T.List[str]]
+    mode: str = 'COMPILER'
 
     def __init__(self, exelist: T.List[str], version: str,
                  for_machine: MachineChoice, info: 'MachineInfo',
@@ -513,6 +514,7 @@ class Compiler(HoldableObject, metaclass=abc.ABCMeta):
         self.linker = linker
         self.info = info
         self.is_cross = is_cross
+        self.modes: T.List[Compiler] = []
 
     def __repr__(self) -> str:
         repr_str = "<{0}: v{1} `{2}`>"
@@ -531,6 +533,9 @@ class Compiler(HoldableObject, metaclass=abc.ABCMeta):
     def get_id(self) -> str:
         return self.id
 
+    def get_modes(self) -> T.List[Compiler]:
+        return self.modes
+
     def get_linker_id(self) -> str:
         # There is not guarantee that we have a dynamic linker instance, as
         # some languages don't have separate linkers and compilers. In those
@@ -1050,6 +1055,9 @@ class Compiler(HoldableObject, metaclass=abc.ABCMeta):
     def get_preprocess_only_args(self) -> T.List[str]:
         raise EnvironmentException('This compiler does not have a preprocessor')
 
+    def get_preprocess_to_file_args(self) -> T.List[str]:
+        return self.get_preprocess_only_args()
+
     def get_default_include_dirs(self) -> T.List[str]:
         # TODO: This is a candidate for returning an immutable list
         return []
@@ -1290,6 +1298,10 @@ class Compiler(HoldableObject, metaclass=abc.ABCMeta):
     def needs_static_linker(self) -> bool:
         raise NotImplementedError(f'There is no static linker for {self.language}')
 
+    def get_preprocessor(self) -> Compiler:
+        """Get compiler's preprocessor.
+        """
+        raise EnvironmentException(f'{self.get_id()} does not support preprocessor')
 
 def get_global_options(lang: str,
                        comp: T.Type[Compiler],

mesonbuild/compilers/mixins/clike.py

@@ -27,6 +27,7 @@ import itertools
 import os
 import re
 import subprocess
+import copy
 import typing as T
 from pathlib import Path
 
@@ -145,6 +146,8 @@ class CLikeCompiler(Compiler):
             self.exe_wrapper = None
         else:
             self.exe_wrapper = exe_wrapper
+        # Lazy initialized in get_preprocessor()
+        self.preprocessor: T.Optional[Compiler] = None
 
     def compiler_args(self, args: T.Optional[T.Iterable[str]] = None) -> CLikeCompilerArgs:
         # This is correct, mypy just doesn't understand co-operative inheritance
@@ -1328,3 +1331,18 @@ class CLikeCompiler(Compiler):
 
     def get_disable_assert_args(self) -> T.List[str]:
         return ['-DNDEBUG']
+
+    @functools.lru_cache(maxsize=None)
+    def can_compile(self, src: 'mesonlib.FileOrString') -> bool:
+        # Files we preprocess can be anything, e.g. .in
+        if self.mode == 'PREPROCESSOR':
+            return True
+        return super().can_compile(src)
+
+    def get_preprocessor(self) -> Compiler:
+        if not self.preprocessor:
+            self.preprocessor = copy.copy(self)
+            self.preprocessor.exelist = self.exelist + self.get_preprocess_to_file_args()
+            self.preprocessor.mode = 'PREPROCESSOR'
+            self.modes.append(self.preprocessor)
+        return self.preprocessor

mesonbuild/compilers/mixins/visualstudio.py

@@ -159,6 +159,9 @@ class VisualStudioLikeCompiler(Compiler, metaclass=abc.ABCMeta):
     def get_preprocess_only_args(self) -> T.List[str]:
         return ['/EP']
 
+    def get_preprocess_to_file_args(self) -> T.List[str]:
+        return ['/EP', '/P']
+
     def get_compile_only_args(self) -> T.List[str]:
         return ['/c']
 
@@ -173,6 +176,8 @@ class VisualStudioLikeCompiler(Compiler, metaclass=abc.ABCMeta):
         return ['/fsanitize=address']
 
     def get_output_args(self, target: str) -> T.List[str]:
+        if self.mode == 'PREPROCESSOR':
+            return ['/Fi' + target]
         if target.endswith('.exe'):
             return ['/Fe' + target]
         return ['/Fo' + target]