C++ module compilation works for a simple project.

mesonbuild/backend/ninjabackend.py

@@ -134,6 +134,11 @@ Please report this error with a test case to the Meson bug tracker.'''.format(te
         raise MesonException(errmsg)
     return quote_re.sub(r'$\g<0>', text)
 
+class TargetDependencyScannerInfo:
+    def __init__(self, private_dir, source2object):
+        self.private_dir = private_dir
+        self.source2object = source2object
+
 @unique
 class Quoting(Enum):
     both = 0
@@ -683,6 +688,10 @@ int dummy;
         return False
 
     def generate_target(self, target):
+        try:
+            os.makedirs(self.get_target_private_dir_abs(target))
+        except FileExistsError:
+            pass
         if isinstance(target, build.CustomTarget):
             self.generate_custom_target(target)
         if isinstance(target, build.RunTarget):
@@ -843,7 +852,7 @@ int dummy;
                     o, s = self.generate_single_compile(target, src, False, [], header_deps)
                     obj_list.append(o)
                     compiled_sources.append(s)
-                    source2object[src] = o
+                    source2object[s] = o
 
         obj_list += self.flatten_object_list(target)
         if is_unity:
@@ -851,7 +860,7 @@ int dummy;
                 o, s = self.generate_single_compile(target, src, True, unity_deps + header_deps)
                 obj_list.append(o)
                 compiled_sources.append(s)
-                source2object[src] = o
+                source2object[s] = o
         linker, stdlib_args = self.determine_linker_and_stdlib_args(target)
         if isinstance(target, build.StaticLibrary) and target.prelink:
             final_obj_list = self.generate_prelink(target, obj_list)
@@ -866,10 +875,15 @@ int dummy;
         if 'cpp' not in target.compilers:
             return
         depscan_file = self.get_dep_scan_file_for(target)
-        pickle_file = os.path.join(self.get_target_private_dir(target), target.name + '.dat').replace('\\', '/')
+        pickle_base = target.name + '.dat'
+        pickle_file = os.path.join(self.get_target_private_dir(target), pickle_base).replace('\\', '/')
+        pickle_abs = os.path.join(self.get_target_private_dir_abs(target), pickle_base).replace('\\', '/')
         rule_name = 'cppscan'
         elem = NinjaBuildElement(self.all_outputs, depscan_file, rule_name, compiled_sources)
         elem.add_item('picklefile', pickle_file)
+        scaninfo = TargetDependencyScannerInfo(self.get_target_private_dir(target), source2object)
+        with open(pickle_abs, 'wb') as p:
+            pickle.dump(scaninfo, p)
         self.add_build(elem)
 
     def process_target_dependencies(self, target):
@@ -1998,7 +2012,7 @@ https://gcc.gnu.org/bugzilla/show_bug.cgi?id=47485'''))
                     # Scanning command is the same for native and cross compilation.
                     continue
                 command = cmd = self.environment.get_build_command() + \
-                    ['--internal', 'scan']
+                    ['--internal', 'depscan']
                 args = ['$picklefile', '$out', '$in']
                 description = 'Module scanner for {}.'.format(langname)
                 rule = NinjaRule(rulename, command, args, description)
@@ -2490,7 +2504,9 @@ https://gcc.gnu.org/bugzilla/show_bug.cgi?id=47485'''))
 
         self.add_dependency_scanner_entries_to_element(target, compiler, element)
         self.add_build(element)
-        return (rel_obj, rel_src)
+        assert(isinstance(rel_obj, str))
+        assert(isinstance(rel_src, str))
+        return (rel_obj, rel_src.replace('\\', '/'))
 
     def add_dependency_scanner_entries_to_element(self, target, compiler, element):
         if compiler.get_language() != 'cpp':

mesonbuild/scripts/depscan.py

@@ -0,0 +1,87 @@
+# Copyright 2020 The Meson development team
+
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+
+#     http://www.apache.org/licenses/LICENSE-2.0
+
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import pathlib
+import pickle
+import re
+import typing as T
+
+import_re = re.compile('\w*import ([a-zA-Z0-9]+);')
+export_re = re.compile('\w*export module ([a-zA-Z0-9]+);')
+
+class DependencyScanner:
+    def __init__(self, pickle_file, outfile, sources):
+        with open(pickle_file, 'rb') as pf:
+            self.target_data = pickle.load(pf)
+        self.outfile = outfile
+        self.sources = sources
+        self.provided_by = {}
+        self.exports = {}
+        self.needs = {}
+        self.sources_with_exports = []
+    
+    def scan_file(self, fname):
+        for line in pathlib.Path(fname).read_text().split('\n'):
+            import_match = import_re.match(line)
+            export_match = export_re.match(line)
+            if import_match:
+                needed = import_match.group(1)
+                if fname in self.needs:
+                    self.needs[fname].append(needed)
+                else:
+                    self.needs[fname] = [needed]
+            if export_match:
+                exported_module = export_match.group(1)
+                if exported_module in self.provided_by:
+                    raise RuntimeError('Multiple files provide module {}.'.format(exported_module))
+                self.sources_with_exports.append(fname)
+                self.provided_by[exported_module] = fname
+                self.exports[fname] = exported_module
+
+    def objname_for(self, src):
+        return self.target_data.source2object[src]
+
+    def ifcname_for(self, src):
+        return '{}.ifc'.format(self.exports[src])
+
+    def scan(self):
+        for s in self.sources:
+            self.scan_file(s)
+        with open(self.outfile, 'w') as ofile:
+            ofile.write('ninja_dyndep_version = 1\n')
+            for src in self.sources:
+                objfilename = self.objname_for(src)
+                if src in self.sources_with_exports:
+                    ifc_entry = '| ' + self.ifcname_for(src)
+                else:
+                    ifc_entry = ''
+                if src in self.needs:
+                    # FIXME, handle all sources, not just the first one
+                    modname = self.needs[src][0]
+                    provider_src = self.provided_by[modname]
+                    provider_ifc = self.ifcname_for(provider_src)
+                    mod_dep = '| ' + provider_ifc
+                else:
+                    mod_dep = ''
+                ofile.write('build {} {}: dyndep {}\n'.format(objfilename,
+                                                              ifc_entry,
+                                                              mod_dep))
+        return 0
+
+def run(args: T.List[str]) -> int:
+    pickle_file = args[0]
+    outfile = args[1]
+    sources = args[2:]
+    scanner = DependencyScanner(pickle_file, outfile, sources)
+    return scanner.scan()