logs: Prepend current subproject name to all messages

Meson used to prepend '|' for each nested subproject to distinguish in
the logs where a subproject start and ends. It is more useful to print
the current subproject name.

Also print the call stack when starting a new subproject to better see
which subproject chain leads to to.

mesonbuild/interpreter.py

@@ -2912,8 +2912,9 @@ external dependencies (including libraries) must go to "dependencies".''')
         self.global_args_frozen = True
 
         mlog.log()
-        with mlog.nested():
-            mlog.log('Executing subproject', mlog.bold(subp_name), 'method', mlog.bold(method), '\n')
+        with mlog.nested(subp_name):
+            stack = ':'.join(self.subproject_stack + [subp_name])
+            mlog.log('Executing subproject', mlog.bold(stack), 'method', mlog.bold(method), '\n')
         try:
             if method == 'meson':
                 return self._do_subproject_meson(subp_name, subdir, default_options, kwargs)
@@ -2926,7 +2927,7 @@ external dependencies (including libraries) must go to "dependencies".''')
             raise
         except Exception as e:
             if not required:
-                with mlog.nested():
+                with mlog.nested(subp_name):
                     # Suppress the 'ERROR:' prefix because this exception is not
                     # fatal and VS CI treat any logs with "ERROR:" as fatal.
                     mlog.exception(e, prefix=mlog.yellow('Exception:'))
@@ -2938,7 +2939,7 @@ external dependencies (including libraries) must go to "dependencies".''')
                              ast: T.Optional[mparser.CodeBlockNode] = None,
                              build_def_files: T.Optional[T.List[str]] = None,
                              is_translated: bool = False) -> SubprojectHolder:
-        with mlog.nested():
+        with mlog.nested(subp_name):
             new_build = self.build.copy()
             subi = Interpreter(new_build, self.backend, subp_name, subdir, self.subproject_dir,
                                self.modules, default_options, ast=ast, is_translated=is_translated)
@@ -2975,7 +2976,7 @@ external dependencies (including libraries) must go to "dependencies".''')
         return self.subprojects[subp_name]
 
     def _do_subproject_cmake(self, subp_name, subdir, subdir_abs, default_options, kwargs):
-        with mlog.nested():
+        with mlog.nested(subp_name):
             new_build = self.build.copy()
             prefix = self.coredata.options[OptionKey('prefix')].value
 
@@ -2995,7 +2996,7 @@ external dependencies (including libraries) must go to "dependencies".''')
             ast = cm_int.pretend_to_be_meson(options.target_options)
 
             mlog.log()
-            with mlog.nested():
+            with mlog.nested('cmake-ast'):
                 mlog.log('Processing generated meson AST')
 
                 # Debug print the generated meson file

mesonbuild/mlog.py

@@ -69,7 +69,7 @@ def setup_console() -> None:
 log_dir = None               # type: T.Optional[str]
 log_file = None              # type: T.Optional[T.TextIO]
 log_fname = 'meson-log.txt'  # type: str
-log_depth = 0                # type: int
+log_depth = []               # type: T.List[str]
 log_timestamp_start = None   # type: T.Optional[float]
 log_fatal_warnings = False   # type: bool
 log_disable_stdout = False   # type: bool
@@ -209,8 +209,8 @@ def force_print(*args: str, **kwargs: T.Any) -> None:
     print(*args, **kwargs)
 
     raw = iostr.getvalue()
-    if log_depth > 0:
-        prepend = '|' * log_depth
+    if log_depth:
+        prepend = log_depth[-1] + '|'
         raw = prepend + raw.replace('\n', '\n' + prepend, raw.count('\n') - 1)
 
     # _Something_ is going to get printed.
@@ -370,10 +370,10 @@ def format_list(input_list: T.List[str]) -> str:
         return ''
 
 @contextmanager
-def nested() -> T.Generator[None, None, None]:
+def nested(name: str = '') -> T.Generator[None, None, None]:
     global log_depth
-    log_depth += 1
+    log_depth.append(name)
     try:
         yield
     finally:
-        log_depth -= 1
+        log_depth.pop()