Merge pull request #5574 from mensinda/cmakeCCmd

CMake subprojects add_custom_command support

5 files changed, 493 insertions, 45 deletions

diff --git a/mesonbuild/ast/printer.py b/mesonbuild/ast/printer.py
index 2de1d0c..c6fb91a 100644
--- a/mesonbuild/ast/printer.py
+++ b/mesonbuild/ast/printer.py
@@ -118,6 +118,7 @@ class AstPrinter(AstVisitor):
             self.newline()
 
     def visit_IndexNode(self, node: mparser.IndexNode):
+        node.iobject.accept(self)
         self.append('[', node)
         node.index.accept(self)
         self.append(']', node)
@@ -181,7 +182,7 @@ class AstPrinter(AstVisitor):
     def visit_ArgumentNode(self, node: mparser.ArgumentNode):
         break_args = (len(node.arguments) + len(node.kwargs)) > self.arg_newline_cutoff
         for i in node.arguments + list(node.kwargs.values()):
-            if not isinstance(i, mparser.ElementaryNode):
+            if not isinstance(i, (mparser.ElementaryNode, mparser.IndexNode)):
                 break_args = True
         if break_args:
             self.newline()
diff --git a/mesonbuild/ast/visitor.py b/mesonbuild/ast/visitor.py
index fab4ed2..de13dae 100644
--- a/mesonbuild/ast/visitor.py
+++ b/mesonbuild/ast/visitor.py
@@ -84,6 +84,7 @@ class AstVisitor:
 
     def visit_IndexNode(self, node: mparser.IndexNode):
         self.visit_default_func(node)
+        node.iobject.accept(self)
         node.index.accept(self)
 
     def visit_MethodNode(self, node: mparser.MethodNode):
diff --git a/mesonbuild/cmake/data/run_ctgt.py b/mesonbuild/cmake/data/run_ctgt.py
new file mode 100755
index 0000000..0a9b80d
--- /dev/null
+++ b/mesonbuild/cmake/data/run_ctgt.py
@@ -0,0 +1,59 @@
+#!/usr/bin/env python3
+
+import argparse
+import subprocess
+import shutil
+import os
+import sys
+
+commands = [[]]
+SEPERATOR = ';;;'
+
+# Generate CMD parameters
+parser = argparse.ArgumentParser(description='Wrapper for add_custom_command')
+parser.add_argument('-d', '--directory', type=str, metavar='D', required=True, help='Working directory to cwd to')
+parser.add_argument('-o', '--outputs', nargs='+', metavar='O', required=True, help='Expected output files')
+parser.add_argument('-O', '--original-outputs', nargs='+', metavar='O', required=True, help='Output files expected by CMake')
+parser.add_argument('commands', nargs=argparse.REMAINDER, help='A "{}" seperated list of commands'.format(SEPERATOR))
+
+# Parse
+args = parser.parse_args()
+
+if len(args.outputs) != len(args.original_outputs):
+    print('Length of output list and original output list differ')
+    sys.exit(1)
+
+for i in args.commands:
+    if i == SEPERATOR:
+        commands += [[]]
+        continue
+
+    commands[-1] += [i]
+
+# Execute
+for i in commands:
+    # Skip empty lists
+    if not i:
+        continue
+
+    subprocess.run(i, cwd=args.directory)
+
+# Copy outputs
+zipped_outputs = zip(args.outputs, args.original_outputs)
+for expected, generated in zipped_outputs:
+    do_copy = False
+    if not os.path.exists(expected):
+        if not os.path.exists(generated):
+            print('Unable to find generated file. This can cause the build to fail:')
+            print(generated)
+            do_copy = False
+        else:
+            do_copy = True
+    elif os.path.exists(generated):
+        if os.path.getmtime(generated) > os.path.getmtime(expected):
+            do_copy = True
+
+    if do_copy:
+        if os.path.exists(expected):
+            os.remove(expected)
+        shutil.copyfile(generated, expected)
diff --git a/mesonbuild/cmake/interpreter.py b/mesonbuild/cmake/interpreter.py
index 88700f1..28a8488 100644
--- a/mesonbuild/cmake/interpreter.py
+++ b/mesonbuild/cmake/interpreter.py
@@ -18,15 +18,33 @@
 from .common import CMakeException
 from .client import CMakeClient, RequestCMakeInputs, RequestConfigure, RequestCompute, RequestCodeModel, CMakeTarget
 from .executor import CMakeExecutor
+from .traceparser import CMakeTraceParser, CMakeGeneratorTarget
 from .. import mlog
 from ..environment import Environment
 from ..mesonlib import MachineChoice
-from ..mparser import Token, BaseNode, CodeBlockNode, FunctionNode, ArrayNode, ArgumentNode, AssignmentNode, BooleanNode, StringNode, IdNode, MethodNode
-from ..compilers.compilers import lang_suffixes, header_suffixes, obj_suffixes
-from subprocess import Popen, PIPE, STDOUT
-from typing import List, Dict, Optional, TYPE_CHECKING
+from ..compilers.compilers import lang_suffixes, header_suffixes, obj_suffixes, is_header
+from subprocess import Popen, PIPE
+from typing import Any, List, Dict, Optional, TYPE_CHECKING
+from threading import Thread
 import os, re
 
+from ..mparser import (
+    Token,
+    BaseNode,
+    CodeBlockNode,
+    FunctionNode,
+    ArrayNode,
+    ArgumentNode,
+    AssignmentNode,
+    BooleanNode,
+    StringNode,
+    IdNode,
+    IndexNode,
+    MethodNode,
+    NumberNode,
+)
+
+
 if TYPE_CHECKING:
     from ..build import Build
     from ..backend.backends import Backend
@@ -87,6 +105,13 @@ blacklist_link_libs = [
     'advapi32.lib'
 ]
 
+# Utility functions to generate local keys
+def _target_key(tgt_name: str) -> str:
+    return '__tgt_{}__'.format(tgt_name)
+
+def _generated_file_key(fname: str) -> str:
+    return '__gen_{}__'.format(os.path.basename(fname))
+
 class ConverterTarget:
     lang_cmake_to_meson = {val.lower(): key for key, val in language_map.items()}
 
@@ -184,11 +209,19 @@ class ConverterTarget:
             temp += [i]
         self.link_libraries = temp
 
+        # Filter out files that are not supported by the language
+        supported = list(header_suffixes) + list(obj_suffixes)
+        for i in self.languages:
+            supported += list(lang_suffixes[i])
+        supported = ['.{}'.format(x) for x in supported]
+        self.sources = [x for x in self.sources if any([x.endswith(y) for y in supported])]
+        self.generated = [x for x in self.generated if any([x.endswith(y) for y in supported])]
+
         # Make paths relative
-        def rel_path(x: str, is_header: bool) -> Optional[str]:
+        def rel_path(x: str, is_header: bool, is_generated: bool) -> Optional[str]:
             if not os.path.isabs(x):
                 x = os.path.normpath(os.path.join(self.src_dir, x))
-            if not os.path.exists(x) and not any([x.endswith(y) for y in obj_suffixes]):
+            if not os.path.exists(x) and not any([x.endswith(y) for y in obj_suffixes]) and not is_generated:
                 mlog.warning('CMake: path', mlog.bold(x), 'does not exist. Ignoring. This can lead to build errors')
                 return None
             if os.path.isabs(x) and os.path.commonpath([x, self.env.get_build_dir()]) == self.env.get_build_dir():
@@ -200,23 +233,29 @@ class ConverterTarget:
                 return os.path.relpath(x, root_src_dir)
             return x
 
+        def custom_target(x: str):
+            key = _generated_file_key(x)
+            if key in output_target_map:
+                ctgt = output_target_map[key]
+                assert(isinstance(ctgt, ConverterCustomTarget))
+                ref = ctgt.get_ref(x)
+                assert(isinstance(ref, CustomTargetReference) and ref.valid())
+                return ref
+            return x
+
         build_dir_rel = os.path.relpath(self.build_dir, os.path.join(self.env.get_build_dir(), subdir))
-        self.includes = list(set([rel_path(x, True) for x in set(self.includes)] + [build_dir_rel]))
-        self.sources = [rel_path(x, False) for x in self.sources]
-        self.generated = [rel_path(x, False) for x in self.generated]
+        self.includes = list(set([rel_path(x, True, False) for x in set(self.includes)] + [build_dir_rel]))
+        self.sources = [rel_path(x, False, False) for x in self.sources]
+        self.generated = [rel_path(x, False, True) for x in self.generated]
+
+        # Resolve custom targets
+        self.generated = [custom_target(x) for x in self.generated]
 
+        # Remove delete entries
         self.includes = [x for x in self.includes if x is not None]
         self.sources = [x for x in self.sources if x is not None]
         self.generated = [x for x in self.generated if x is not None]
 
-        # Filter out files that are not supported by the language
-        supported = list(header_suffixes) + list(obj_suffixes)
-        for i in self.languages:
-            supported += list(lang_suffixes[i])
-        supported = ['.{}'.format(x) for x in supported]
-        self.sources = [x for x in self.sources if any([x.endswith(y) for y in supported])]
-        self.generated = [x for x in self.generated if any([x.endswith(y) for y in supported])]
-
         # Make sure '.' is always in the include directories
         if '.' not in self.includes:
             self.includes += ['.']
@@ -239,7 +278,8 @@ class ConverterTarget:
 
     def process_object_libs(self, obj_target_list: List['ConverterTarget']):
         # Try to detect the object library(s) from the generated input sources
-        temp = [os.path.basename(x) for x in self.generated]
+        temp = [x for x in self.generated if isinstance(x, str)]
+        temp = [os.path.basename(x) for x in temp]
         temp = [x for x in temp if any([x.endswith('.' + y) for y in obj_suffixes])]
         temp = [os.path.splitext(x)[0] for x in temp]
         # Temp now stores the source filenames of the object files
@@ -251,7 +291,7 @@ class ConverterTarget:
                     break
 
         # Filter out object files from the sources
-        self.generated = [x for x in self.generated if not any([x.endswith('.' + y) for y in obj_suffixes])]
+        self.generated = [x for x in self.generated if not isinstance(x, str) or not any([x.endswith('.' + y) for y in obj_suffixes])]
 
     def meson_func(self) -> str:
         return target_type_map.get(self.type.upper())
@@ -277,6 +317,113 @@ class ConverterTarget:
         for key, val in self.compile_opts.items():
             mlog.log('    -', key, '=', mlog.bold(str(val)))
 
+class CustomTargetReference:
+    def __init__(self, ctgt: 'ConverterCustomTarget', index: int):
+        self.ctgt = ctgt    # type: ConverterCustomTarget
+        self.index = index  # type: int
+
+    def __repr__(self) -> str:
+        if self.valid():
+            return '<{}: {} [{}]>'.format(self.__class__.__name__, self.ctgt.name, self.ctgt.outputs[self.index])
+        else:
+            return '<{}: INVALID REFERENCE>'.format(self.__class__.__name__)
+
+    def valid(self) -> bool:
+        return self.ctgt is not None and self.index >= 0
+
+    def filename(self) -> str:
+        return self.ctgt.outputs[self.index]
+
+class ConverterCustomTarget:
+    tgt_counter = 0  # type: int
+
+    def __init__(self, target: CMakeGeneratorTarget):
+        self.name = 'custom_tgt_{}'.format(ConverterCustomTarget.tgt_counter)
+        self.original_outputs = list(target.outputs)
+        self.outputs = [os.path.basename(x) for x in self.original_outputs]
+        self.command = target.command
+        self.working_dir = target.working_dir
+        self.depends_raw = target.depends
+        self.inputs = []
+        self.depends = []
+
+        ConverterCustomTarget.tgt_counter += 1
+
+    def __repr__(self) -> str:
+        return '<{}: {}>'.format(self.__class__.__name__, self.outputs)
+
+    def postprocess(self, output_target_map: dict, root_src_dir: str, subdir: str, build_dir: str) -> None:
+        # Default the working directory to the CMake build dir. This
+        # is not 100% correct, since it should be the value of
+        # ${CMAKE_CURRENT_BINARY_DIR} when add_custom_command is
+        # called. However, keeping track of this variable is not
+        # trivial and the current solution should work in most cases.
+        if not self.working_dir:
+            self.working_dir = build_dir
+
+        # relative paths in the working directory are always relative
+        # to ${CMAKE_CURRENT_BINARY_DIR} (see note above)
+        if not os.path.isabs(self.working_dir):
+            self.working_dir = os.path.normpath(os.path.join(build_dir, self.working_dir))
+
+        # Modify the original outputs if they are relative. Again,
+        # relative paths are relative to ${CMAKE_CURRENT_BINARY_DIR}
+        # and the first disclaimer is stil in effect
+        def ensure_absolute(x: str):
+            if os.path.isabs(x):
+                return x
+            else:
+                return os.path.normpath(os.path.join(build_dir, x))
+        self.original_outputs = [ensure_absolute(x) for x in self.original_outputs]
+
+        # Check if the command is a build target
+        commands = []
+        for i in self.command:
+            assert(isinstance(i, list))
+            cmd = []
+
+            for j in i:
+                target_key = _target_key(j)
+                if target_key in output_target_map:
+                    cmd += [output_target_map[target_key]]
+                else:
+                    cmd += [j]
+
+            commands += [cmd]
+        self.command = commands
+
+        # Check dependencies and input files
+        for i in self.depends_raw:
+            tgt_key = _target_key(i)
+            gen_key = _generated_file_key(i)
+
+            if os.path.basename(i) in output_target_map:
+                self.depends += [output_target_map[os.path.basename(i)]]
+            elif tgt_key in output_target_map:
+                self.depends += [output_target_map[tgt_key]]
+            elif gen_key in output_target_map:
+                self.inputs += [output_target_map[gen_key].get_ref(i)]
+            elif not os.path.isabs(i) and os.path.exists(os.path.join(root_src_dir, i)):
+                self.inputs += [i]
+            elif os.path.isabs(i) and os.path.exists(i) and os.path.commonpath([i, root_src_dir]) == root_src_dir:
+                self.inputs += [os.path.relpath(i, root_src_dir)]
+
+    def get_ref(self, fname: str) -> Optional[CustomTargetReference]:
+        try:
+            idx = self.outputs.index(os.path.basename(fname))
+            return CustomTargetReference(self, idx)
+        except ValueError:
+            return None
+
+    def log(self) -> None:
+        mlog.log('Custom Target', mlog.bold(self.name))
+        mlog.log('  -- command:     ', mlog.bold(str(self.command)))
+        mlog.log('  -- outputs:     ', mlog.bold(str(self.outputs)))
+        mlog.log('  -- working_dir: ', mlog.bold(str(self.working_dir)))
+        mlog.log('  -- depends_raw: ', mlog.bold(str(self.depends_raw)))
+        mlog.log('  -- inputs:      ', mlog.bold(str(self.inputs)))
+        mlog.log('  -- depends:     ', mlog.bold(str(self.depends)))
+
 class CMakeInterpreter:
     def __init__(self, build: 'Build', subdir: str, src_dir: str, install_prefix: str, env: Environment, backend: 'Backend'):
         assert(hasattr(backend, 'name'))
@@ -293,11 +440,14 @@ class CMakeInterpreter:
         # Raw CMake results
         self.bs_files = []
         self.codemodel = None
+        self.raw_trace = None
 
         # Analysed data
         self.project_name = ''
         self.languages = []
         self.targets = []
+        self.custom_targets = []  # type: List[ConverterCustomTarget]
+        self.trace = CMakeTraceParser()
 
         # Generated meson data
         self.generated_targets = {}
@@ -327,6 +477,7 @@ class CMakeInterpreter:
                 cmake_args += ['-DCMAKE_LINKER={}'.format(comp.get_linker_exelist()[0])]
         cmake_args += ['-G', generator]
         cmake_args += ['-DCMAKE_INSTALL_PREFIX={}'.format(self.install_prefix)]
+        cmake_args += ['--trace', '--trace-expand']
         cmake_args += extra_cmake_options
 
         # Run CMake
@@ -338,17 +489,25 @@ class CMakeInterpreter:
             os.makedirs(self.build_dir, exist_ok=True)
             os_env = os.environ.copy()
             os_env['LC_ALL'] = 'C'
-            proc = Popen(cmake_args + [self.src_dir], stdout=PIPE, stderr=STDOUT, cwd=self.build_dir, env=os_env)
+            proc = Popen(cmake_args + [self.src_dir], stdout=PIPE, stderr=PIPE, cwd=self.build_dir, env=os_env)
 
-            # Print CMake log in realtime
-            while True:
-                line = proc.stdout.readline()
-                if not line:
-                    break
-                mlog.log(line.decode('utf-8').strip('\n'))
+            def print_stdout():
+                while True:
+                    line = proc.stdout.readline()
+                    if not line:
+                        break
+                    mlog.log(line.decode('utf-8').strip('\n'))
+                proc.stdout.close()
 
-            # Wait for CMake to finish
-            proc.communicate()
+            t = Thread(target=print_stdout)
+            t.start()
+
+            self.raw_trace = proc.stderr.read()
+            self.raw_trace = self.raw_trace.decode('utf-8')
+            proc.stderr.close()
+            proc.wait()
+
+            t.join()
 
         mlog.log()
         h = mlog.green('SUCCEEDED') if proc.returncode == 0 else mlog.red('FAILED')
@@ -391,6 +550,11 @@ class CMakeInterpreter:
         self.project_name = ''
         self.languages = []
         self.targets = []
+        self.custom_targets = []
+        self.trace = CMakeTraceParser(permissive=True)
+
+        # Parse the trace
+        self.trace.parse(self.raw_trace)
 
         # Find all targets
         for i in self.codemodel.configs:
@@ -401,13 +565,24 @@ class CMakeInterpreter:
                     if k.type not in skip_targets:
                         self.targets += [ConverterTarget(k, self.env)]
 
-        output_target_map = {x.full_name: x for x in self.targets}
+        for i in self.trace.custom_targets:
+            self.custom_targets += [ConverterCustomTarget(i)]
+
+        # generate the output_target_map
+        output_target_map = {}
+        output_target_map.update({x.full_name: x for x in self.targets})
+        output_target_map.update({_target_key(x.name): x for x in self.targets})
         for i in self.targets:
             for j in i.artifacts:
                 output_target_map[os.path.basename(j)] = i
+        for i in self.custom_targets:
+            for j in i.original_outputs:
+                output_target_map[_generated_file_key(j)] = i
         object_libs = []
 
         # First pass: Basic target cleanup
+        for i in self.custom_targets:
+            i.postprocess(output_target_map, self.src_dir, self.subdir, self.build_dir)
         for i in self.targets:
             i.postprocess(output_target_map, self.src_dir, self.subdir, self.install_prefix)
             if i.type == 'OBJECT_LIBRARY':
@@ -418,7 +593,7 @@ class CMakeInterpreter:
         for i in self.targets:
             i.process_object_libs(object_libs)
 
-        mlog.log('CMake project', mlog.bold(self.project_name), 'has', mlog.bold(str(len(self.targets))), 'build targets.')
+        mlog.log('CMake project', mlog.bold(self.project_name), 'has', mlog.bold(str(len(self.targets) + len(self.custom_targets))), 'build targets.')
 
     def pretend_to_be_meson(self) -> CodeBlockNode:
         if not self.project_name:
@@ -433,15 +608,23 @@ class CMakeInterpreter:
         def id_node(value: str) -> IdNode:
             return IdNode(token(val=value))
 
+        def number(value: int) -> NumberNode:
+            return NumberNode(token(val=value))
+
         def nodeify(value):
             if isinstance(value, str):
                 return string(value)
             elif isinstance(value, bool):
                 return BooleanNode(token(), value)
+            elif isinstance(value, int):
+                return number(value)
             elif isinstance(value, list):
                 return array(value)
             return value
 
+        def indexed(node: BaseNode, index: int) -> IndexNode:
+            return IndexNode(node, nodeify(index))
+
         def array(elements) -> ArrayNode:
             args = ArgumentNode(token())
             if not isinstance(elements, list):
@@ -480,12 +663,30 @@ class CMakeInterpreter:
         # Generate the root code block and the project function call
         root_cb = CodeBlockNode(token())
         root_cb.lines += [function('project', [self.project_name] + self.languages)]
+
+        # Add the run script for custom commands
+        run_script = '{}/data/run_ctgt.py'.format(os.path.dirname(os.path.realpath(__file__)))
+        run_script_var = 'ctgt_run_script'
+        root_cb.lines += [assign(run_script_var, function('find_program', [[run_script]], {'required': True}))]
+
+        # Add the targets
         processed = {}
 
+        def resolve_ctgt_ref(ref: CustomTargetReference) -> BaseNode:
+            tgt_var = processed[ref.ctgt.name]['tgt']
+            if len(ref.ctgt.outputs) == 1:
+                return id_node(tgt_var)
+            else:
+                return indexed(id_node(tgt_var), ref.index)
+
         def process_target(tgt: ConverterTarget):
             # First handle inter target dependencies
             link_with = []
             objec_libs = []
+            sources = []
+            generated = []
+            generated_filenames = []
+            custom_targets = []
             for i in tgt.link_with:
                 assert(isinstance(i, ConverterTarget))
                 if i.name not in processed:
@@ -497,6 +698,32 @@ class CMakeInterpreter:
                     process_target(i)
                 objec_libs += [processed[i.name]['tgt']]
 
+            # Generate the source list and handle generated sources
+            for i in tgt.sources + tgt.generated:
+                if isinstance(i, CustomTargetReference):
+                    if i.ctgt.name not in processed:
+                        process_custom_target(i.ctgt)
+                    generated += [resolve_ctgt_ref(i)]
+                    generated_filenames += [i.filename()]
+                    if i.ctgt not in custom_targets:
+                        custom_targets += [i.ctgt]
+                else:
+                    sources += [i]
+
+            # Add all header files from all used custom targets. This
+            # ensures that all custom targets are built before any
+            # sources of the current target are compiled and thus all
+            # header files are present. This step is necessary because
+            # CMake always ensures that a custom target is executed
+            # before another target if at least one output is used.
+            for i in custom_targets:
+                for j in i.outputs:
+                    if not is_header(j) or j in generated_filenames:
+                        continue
+
+                    generated += [resolve_ctgt_ref(i.get_ref(j))]
+                    generated_filenames += [j]
+
             # Determine the meson function to use for the build target
             tgt_func = tgt.meson_func()
             if not tgt_func:
@@ -540,15 +767,59 @@ class CMakeInterpreter:
 
             # Generate the function nodes
             inc_node = assign(inc_var, function('include_directories', tgt.includes))
-            src_node = assign(src_var, function('files', tgt.sources + tgt.generated))
-            tgt_node = assign(tgt_var, function(tgt_func, [base_name, id_node(src_var)], tgt_kwargs))
+            src_node = assign(src_var, function('files', sources))
+            tgt_node = assign(tgt_var, function(tgt_func, [base_name, [id_node(src_var)] + generated], tgt_kwargs))
             dep_node = assign(dep_var, function('declare_dependency', kwargs=dep_kwargs))
 
             # Add the nodes to the ast
             root_cb.lines += [inc_node, src_node, tgt_node, dep_node]
             processed[tgt.name] = {'inc': inc_var, 'src': src_var, 'dep': dep_var, 'tgt': tgt_var, 'func': tgt_func}
 
+        def process_custom_target(tgt: ConverterCustomTarget) -> None:
+            # CMake allows to specify multiple commands in a custom target.
+            # To map this to meson, a helper script is used to execute all
+            # commands in order. This addtionally allows setting the working
+            # directory.
+
+            tgt_var = tgt.name  # type: str
+
+            def resolve_source(x: Any) -> Any:
+                if isinstance(x, ConverterTarget):
+                    if x.name not in processed:
+                        process_target(x)
+                    return id_node(x.name)
+                elif isinstance(x, CustomTargetReference):
+                    if x.ctgt.name not in processed:
+                        process_custom_target(x.ctgt)
+                    return resolve_ctgt_ref(x)
+                else:
+                    return x
+
+            # Generate the command list
+            command = []
+            command += [id_node(run_script_var)]
+            command += ['-o', '@OUTPUT@']
+            command += ['-O'] + tgt.original_outputs
+            command += ['-d', tgt.working_dir]
+
+            # Generate the commands. Subcommands are seperated by ';;;'
+            for cmd in tgt.command:
+                command += [resolve_source(x) for x in cmd] + [';;;']
+
+            tgt_kwargs = {
+                'input': [resolve_source(x) for x in tgt.inputs],
+                'output': tgt.outputs,
+                'command': command,
+                'depends': [resolve_source(x) for x in tgt.depends],
+            }
+
+            root_cb.lines += [assign(tgt_var, function('custom_target', [tgt.name], tgt_kwargs))]
+            processed[tgt.name] = {'inc': None, 'src': None, 'dep': None, 'tgt': tgt_var, 'func': 'custom_target'}
+
         # Now generate the target function calls
+        for i in self.custom_targets:
+            if i.name not in processed:
+                process_custom_target(i)
         for i in self.targets:
             if i.name not in processed:
                 process_target(i)
diff --git a/mesonbuild/cmake/traceparser.py b/mesonbuild/cmake/traceparser.py
index 1dcf6d2..4b87319 100644
--- a/mesonbuild/cmake/traceparser.py
+++ b/mesonbuild/cmake/traceparser.py
@@ -16,9 +16,11 @@
 # or an interpreter-based tool.
 
 from .common import CMakeException
+from .. import mlog
 
-from typing import List, Tuple
+from typing import List, Tuple, Optional
 import re
+import os
 
 class CMakeTraceLine:
     def __init__(self, file, line, func, args):
@@ -46,14 +48,26 @@ class CMakeTarget:
             propSTR += "      '{}': {}\n".format(i, self.properies[i])
         return s.format(self.name, self.type, propSTR)
 
-class CMakeTraceParser:
+class CMakeGeneratorTarget:
     def __init__(self):
+        self.outputs = []        # type: List[str]
+        self.command = []        # type: List[List[str]]
+        self.working_dir = None  # type: Optional[str]
+        self.depends = []        # type: List[str]
+
+class CMakeTraceParser:
+    def __init__(self, permissive: bool = False):
         # Dict of CMake variables: '<var_name>': ['list', 'of', 'values']
         self.vars = {}
 
         # Dict of CMakeTarget
         self.targets = {}
 
+        # List of targes that were added with add_custom_command to generate files
+        self.custom_targets = []  # type: List[CMakeGeneratorTarget]
+
+        self.permissive = permissive  # type: bool
+
     def parse(self, trace: str) -> None:
         # First parse the trace
         lexer1 = self._lex_trace(trace)
@@ -64,6 +78,7 @@ class CMakeTraceParser:
             'unset': self._cmake_unset,
             'add_executable': self._cmake_add_executable,
             'add_library': self._cmake_add_library,
+            'add_custom_command': self._cmake_add_custom_command,
             'add_custom_target': self._cmake_add_custom_target,
             'set_property': self._cmake_set_property,
             'set_target_properties': self._cmake_set_target_properties
@@ -102,6 +117,14 @@ class CMakeTraceParser:
             return True
         return False
 
+    def _gen_exception(self, function: str, error: str, tline: CMakeTraceLine) -> None:
+        # Generate an exception if the parser is not in permissive mode
+
+        if self.permissive:
+            mlog.debug('CMake trace warning: {}() {}\n{}'.format(function, error, tline))
+            return None
+        raise CMakeException('CMake: {}() {}\n{}'.format(function, error, tline))
+
     def _cmake_set(self, tline: CMakeTraceLine) -> None:
         """Handler for the CMake set() function in all variaties.
 
@@ -132,7 +155,7 @@ class CMakeTraceParser:
             args.append(i)
 
         if len(args) < 1:
-            raise CMakeException('CMake: set() requires at least one argument\n{}'.format(tline))
+            return self._gen_exception('set', 'requires at least one argument', tline)
 
         # Now that we've removed extra arguments all that should be left is the
         # variable identifier and the value, join the value back together to
@@ -151,7 +174,7 @@ class CMakeTraceParser:
     def _cmake_unset(self, tline: CMakeTraceLine):
         # DOC: https://cmake.org/cmake/help/latest/command/unset.html
         if len(tline.args) < 1:
-            raise CMakeException('CMake: unset() requires at least one argument\n{}'.format(tline))
+            return self._gen_exception('unset', 'requires at least one argument', tline)
 
         if tline.args[0] in self.vars:
             del self.vars[tline.args[0]]
@@ -162,12 +185,12 @@ class CMakeTraceParser:
 
         # Make sure the exe is imported
         if 'IMPORTED' not in args:
-            raise CMakeException('CMake: add_executable() non imported executables are not supported\n{}'.format(tline))
+            return self._gen_exception('add_executable', 'non imported executables are not supported', tline)
 
         args.remove('IMPORTED')
 
         if len(args) < 1:
-            raise CMakeException('CMake: add_executable() requires at least 1 argument\n{}'.format(tline))
+            return self._gen_exception('add_executable', 'requires at least 1 argument', tline)
 
         self.targets[args[0]] = CMakeTarget(args[0], 'EXECUTABLE', {})
 
@@ -177,21 +200,82 @@ class CMakeTraceParser:
 
         # Make sure the lib is imported
         if 'IMPORTED' not in args:
-            raise CMakeException('CMake: add_library() non imported libraries are not supported\n{}'.format(tline))
+            return self._gen_exception('add_library', 'non imported libraries are not supported', tline)
 
         args.remove('IMPORTED')
 
         # No only look at the first two arguments (target_name and target_type) and ignore the rest
         if len(args) < 2:
-            raise CMakeException('CMake: add_library() requires at least 2 arguments\n{}'.format(tline))
+            return self._gen_exception('add_library', 'requires at least 2 arguments', tline)
 
         self.targets[args[0]] = CMakeTarget(args[0], args[1], {})
 
+    def _cmake_add_custom_command(self, tline: CMakeTraceLine):
+        # DOC: https://cmake.org/cmake/help/latest/command/add_custom_command.html
+        args = list(tline.args) # Make a working copy
+
+        if not args:
+            return self._gen_exception('add_custom_command', 'requires at least 1 argument', tline)
+
+        # Skip the second function signature
+        if args[0] == 'TARGET':
+            return self._gen_exception('add_custom_command', 'TARGET syntax is currently not supported', tline)
+
+        magic_keys = ['OUTPUT', 'COMMAND', 'MAIN_DEPENDENCY', 'DEPENDS', 'BYPRODUCTS',
+                      'IMPLICIT_DEPENDS', 'WORKING_DIRECTORY', 'COMMENT', 'DEPFILE',
+                      'JOB_POOL', 'VERBATIM', 'APPEND', 'USES_TERMINAL', 'COMMAND_EXPAND_LISTS']
+
+        target = CMakeGeneratorTarget()
+
+        def handle_output(key: str, target: CMakeGeneratorTarget) -> None:
+            target.outputs += [key]
+
+        def handle_command(key: str, target: CMakeGeneratorTarget) -> None:
+            if key == 'ARGS':
+                return
+            target.command[-1] += [key]
+
+        def handle_depends(key: str, target: CMakeGeneratorTarget) -> None:
+            target.depends += [key]
+
+        def handle_working_dir(key: str, target: CMakeGeneratorTarget) -> None:
+            if target.working_dir is None:
+                target.working_dir = key
+            else:
+                target.working_dir += ' '
+                target.working_dir += key
+
+        fn = None
+
+        for i in args:
+            if i in magic_keys:
+                if i == 'OUTPUT':
+                    fn = handle_output
+                elif i == 'DEPENDS':
+                    fn = handle_depends
+                elif i == 'WORKING_DIRECTORY':
+                    fn = handle_working_dir
+                elif i == 'COMMAND':
+                    fn = handle_command
+                    target.command += [[]]
+                else:
+                    fn = None
+                continue
+
+            if fn is not None:
+                fn(i, target)
+
+        target.outputs = self._guess_files(target.outputs)
+        target.depends = self._guess_files(target.depends)
+        target.command = [self._guess_files(x) for x in target.command]
+
+        self.custom_targets += [target]
+
     def _cmake_add_custom_target(self, tline: CMakeTraceLine):
         # DOC: https://cmake.org/cmake/help/latest/command/add_custom_target.html
         # We only the first parameter (the target name) is interesting
         if len(tline.args) < 1:
-            raise CMakeException('CMake: add_custom_target() requires at least one argument\n{}'.format(tline))
+            return self._gen_exception('add_custom_target', 'requires at least one argument', tline)
 
         self.targets[tline.args[0]] = CMakeTarget(tline.args[0], 'CUSTOM', {})
 
@@ -219,7 +303,7 @@ class CMakeTraceParser:
             targets.append(curr)
 
         if not args:
-            raise CMakeException('CMake: set_property() faild to parse argument list\n{}'.format(tline))
+            return self._gen_exception('set_property', 'faild to parse argument list', tline)
 
         if len(args) == 1:
             # Tries to set property to nothing so nothing has to be done
@@ -232,7 +316,7 @@ class CMakeTraceParser:
 
         for i in targets:
             if i not in self.targets:
-                raise CMakeException('CMake: set_property() TARGET {} not found\n{}'.format(i, tline))
+                return self._gen_exception('set_property', 'TARGET {} not found'.format(i), tline)
 
             if identifier not in self.targets[i].properies:
                 self.targets[i].properies[identifier] = []
@@ -284,7 +368,7 @@ class CMakeTraceParser:
         for name, value in arglist:
             for i in targets:
                 if i not in self.targets:
-                    raise CMakeException('CMake: set_target_properties() TARGET {} not found\n{}'.format(i, tline))
+                    return self._gen_exception('set_target_properties', 'TARGET {} not found'.format(i), tline)
 
                 self.targets[i].properies[name] = value
 
@@ -315,3 +399,35 @@ class CMakeTraceParser:
             args = list(map(lambda x: reg_genexp.sub('', x), args)) # Remove generator expressions
 
             yield CMakeTraceLine(file, line, func, args)
+
+    def _guess_files(self, broken_list: List[str]) -> List[str]:
+        #Try joining file paths that contain spaces
+
+        reg_start = re.compile(r'^([A-Za-z]:)?/.*/[^./]+$')
+        reg_end = re.compile(r'^.*\.[a-zA-Z]+$')
+
+        fixed_list = []  # type: List[str]
+        curr_str = None  # type: Optional[str]
+
+        for i in broken_list:
+            if curr_str is None:
+                curr_str = i
+            elif os.path.isfile(curr_str):
+                # Abort concatination if curr_str is an existing file
+                fixed_list += [curr_str]
+                curr_str = i
+            elif not reg_start.match(curr_str):
+                # Abort concatination if curr_str no longer matches the regex
+                fixed_list += [curr_str]
+                curr_str = i
+            elif reg_end.match(i):
+                # File detected
+                curr_str = '{} {}'.format(curr_str, i)
+                fixed_list += [curr_str]
+                curr_str = None
+            else:
+                curr_str = '{} {}'.format(curr_str, i)
+
+        if curr_str:
+            fixed_list += [curr_str]
+        return fixed_list