preprocess: Allow preprocessing any file extensions

mesonbuild/backend/ninjabackend.py

@@ -856,6 +856,10 @@ class NinjaBackend(backends.Backend):
             self.generate_swift_target(target)
             return
 
+        # CompileTarget compiles all its sources and does not do a final link.
+        # This is, for example, a preprocessor.
+        is_compile_target = isinstance(target, build.CompileTarget)
+
         # Preexisting target C/C++ sources to be built; dict of full path to
         # source relative to build root and the original File object.
         target_sources: T.MutableMapping[str, File]
@@ -922,6 +926,8 @@ class NinjaBackend(backends.Backend):
                 obj_list.append(rel_src)
             elif self.environment.is_library(rel_src) or modules.is_module_library(rel_src):
                 pass
+            elif is_compile_target:
+                generated_source_files.append(raw_src)
             else:
                 # Assume anything not specifically a source file is a header. This is because
                 # people generate files with weird suffixes (.inc, .fh) that they then include
@@ -992,7 +998,7 @@ class NinjaBackend(backends.Backend):
 
         # Generate compile targets for all the preexisting sources for this target
         for src in target_sources.values():
-            if not self.environment.is_header(src):
+            if not self.environment.is_header(src) or is_compile_target:
                 if self.environment.is_llvm_ir(src):
                     o, s = self.generate_llvm_ir_compile(target, src)
                     obj_list.append(o)
@@ -1015,7 +1021,7 @@ class NinjaBackend(backends.Backend):
                 obj_list.append(o)
                 compiled_sources.append(s)
                 source2object[s] = o
-        if isinstance(target, build.CompileTarget):
+        if is_compile_target:
             # Skip the link stage for this special type of target
             return
         linker, stdlib_args = self.determine_linker_and_stdlib_args(target)

test cases/common/259 preprocess/meson.build

@@ -6,16 +6,16 @@ add_project_arguments(['-DFOO=0', '-DBAR=0'], language: 'c')
 
 fs = import('fs')
 bar_content = fs.read('bar.c')
-bar_c = custom_target(
+bar_x = custom_target(
   input: 'bar.c',
-  output: 'bar.c',
+  output: 'bar.x',
   command: ['python3', '-c', '''import sys;print(sys.argv[1].replace('@BAR@', 'bar'))''', bar_content],
   capture: true,
 )
 
 dep = declare_dependency(compile_args: '-DPLOP=0')
 
-pp_files = cc.preprocess('foo.c', bar_c, output: '@PLAINNAME@', dependencies: dep)
+pp_files = cc.preprocess('foo.c', bar_x, output: '@PLAINNAME@.c', dependencies: dep)
 
 foreach f : pp_files
   message(f.full_path())