Unify message(), format() and fstring formatting

Share a common function to convert objects to display strings for
consistency.

While at it, also add support for formatting user options.

3 files changed, 37 insertions, 9 deletions

diff --git a/mesonbuild/interpreterbase/__init__.py b/mesonbuild/interpreterbase/__init__.py
index f0c2002..3cb9530 100644
--- a/mesonbuild/interpreterbase/__init__.py
+++ b/mesonbuild/interpreterbase/__init__.py
@@ -35,6 +35,7 @@ __all__ = [
     'default_resolve_key',
     'flatten',
     'resolve_second_level_holders',
+    'stringifyUserArguments',
 
     'noPosargs',
     'noKwargs',
@@ -134,6 +135,11 @@ from .exceptions import (
 )
 
 from .disabler import Disabler, is_disabled
-from .helpers import default_resolve_key, flatten, resolve_second_level_holders
+from .helpers import (
+    default_resolve_key,
+    flatten,
+    resolve_second_level_holders,
+    stringifyUserArguments,
+)
 from .interpreterbase import InterpreterBase
 from .operator import MesonOperator
diff --git a/mesonbuild/interpreterbase/helpers.py b/mesonbuild/interpreterbase/helpers.py
index 2196b4e..f2ee1b1 100644
--- a/mesonbuild/interpreterbase/helpers.py
+++ b/mesonbuild/interpreterbase/helpers.py
@@ -14,13 +14,15 @@
 from __future__ import annotations
 
 from .. import mesonlib, mparser
-from .exceptions import InterpreterException
+from .exceptions import InterpreterException, InvalidArguments
+from ..coredata import UserOption
+
 
 import collections.abc
 import typing as T
 
 if T.TYPE_CHECKING:
-    from .baseobjects import TYPE_var, TYPE_kwargs
+    from .baseobjects import TYPE_var, TYPE_kwargs, SubProject
 
 def flatten(args: T.Union['TYPE_var', T.List['TYPE_var']]) -> T.List['TYPE_var']:
     if isinstance(args, mparser.StringNode):
@@ -54,3 +56,22 @@ def default_resolve_key(key: mparser.BaseNode) -> str:
     if not isinstance(key, mparser.IdNode):
         raise InterpreterException('Invalid kwargs format.')
     return key.value
+
+def stringifyUserArguments(args: TYPE_var, subproject: SubProject, quote: bool = False) -> str:
+    if isinstance(args, str):
+        return f"'{args}'" if quote else args
+    elif isinstance(args, bool):
+        return 'true' if args else 'false'
+    elif isinstance(args, int):
+        return str(args)
+    elif isinstance(args, list):
+        return '[%s]' % ', '.join([stringifyUserArguments(x, subproject, True) for x in args])
+    elif isinstance(args, dict):
+        l = ['{} : {}'.format(stringifyUserArguments(k, subproject, True),
+                              stringifyUserArguments(v, subproject, True)) for k, v in args.items()]
+        return '{%s}' % ', '.join(l)
+    elif isinstance(args, UserOption):
+        from .decorators import FeatureNew
+        FeatureNew.single_use('User option in string format', '1.3.0', subproject)
+        return stringifyUserArguments(args.printable_value(), subproject)
+    raise InvalidArguments('Value other than strings, integers, bools, options, dictionaries and lists thereof.')
diff --git a/mesonbuild/interpreterbase/interpreterbase.py b/mesonbuild/interpreterbase/interpreterbase.py
index 9aff5b9..d23a23d 100644
--- a/mesonbuild/interpreterbase/interpreterbase.py
+++ b/mesonbuild/interpreterbase/interpreterbase.py
@@ -40,7 +40,7 @@ from .exceptions import (
 
 from .decorators import FeatureNew
 from .disabler import Disabler, is_disabled
-from .helpers import default_resolve_key, flatten, resolve_second_level_holders
+from .helpers import default_resolve_key, flatten, resolve_second_level_holders, stringifyUserArguments
 from .operator import MesonOperator
 from ._unholder import _unholder
 
@@ -433,11 +433,12 @@ class InterpreterBase:
             var = str(match.group(1))
             try:
                 val = _unholder(self.variables[var])
-                if not isinstance(val, (str, int, float, bool)):
-                    raise InvalidCode(f'Identifier "{var}" does not name a formattable variable ' +
-                                      '(has to be an integer, a string, a floating point number or a boolean).')
-
-                return str(val)
+                if isinstance(val, (list, dict)):
+                    FeatureNew.single_use('List or dictionary in f-string', '1.3.0', self.subproject, location=self.current_node)
+                try:
+                    return stringifyUserArguments(val, self.subproject)
+                except InvalidArguments as e:
+                    raise InvalidArguments(f'f-string: {str(e)}')
             except KeyError:
                 raise InvalidCode(f'Identifier "{var}" does not name a variable.')