Merge pull request #10332 from xclaesse/std-opt

c_std, cpp_std: Change to a list of desired versions in preference order

1 files changed, 63 insertions, 13 deletions

diff --git a/mesonbuild/coredata.py b/mesonbuild/coredata.py
index b0dad13..4b0f9af 100644
--- a/mesonbuild/coredata.py
+++ b/mesonbuild/coredata.py
@@ -248,23 +248,17 @@ class UserComboOption(UserOption[str]):
 
 class UserArrayOption(UserOption[T.List[str]]):
     def __init__(self, description: str, value: T.Union[str, T.List[str]],
-                 split_args: bool = False, user_input: bool = False,
+                 split_args: bool = False,
                  allow_dups: bool = False, yielding: bool = DEFAULT_YIELDING,
                  choices: T.Optional[T.List[str]] = None,
                  deprecated: T.Union[bool, str, T.Dict[str, str], T.List[str]] = False):
         super().__init__(description, choices if choices is not None else [], yielding, deprecated)
         self.split_args = split_args
         self.allow_dups = allow_dups
-        self.value = self.validate_value(value, user_input=user_input)
-
-    def listify(self, value: T.Union[str, T.List[str]], user_input: bool = True) -> T.List[str]:
-        # User input is for options defined on the command line (via -D
-        # options). Users can put their input in as a comma separated
-        # string, but for defining options in meson_options.txt the format
-        # should match that of a combo
-        if not user_input and isinstance(value, str) and not value.startswith('['):
-            raise MesonException('Value does not define an array: ' + value)
+        self.set_value(value)
 
+    @staticmethod
+    def listify_value(value: T.Union[str, T.List[str]], shlex_split_args: bool = False) -> T.List[str]:
         if isinstance(value, str):
             if value.startswith('['):
                 try:
@@ -274,7 +268,7 @@ class UserArrayOption(UserOption[T.List[str]]):
             elif value == '':
                 newvalue = []
             else:
-                if self.split_args:
+                if shlex_split_args:
                     newvalue = split_args(value)
                 else:
                     newvalue = [v.strip() for v in value.split(',')]
@@ -284,8 +278,11 @@ class UserArrayOption(UserOption[T.List[str]]):
             raise MesonException(f'"{value}" should be a string array, but it is not')
         return newvalue
 
-    def validate_value(self, value: T.Union[str, T.List[str]], user_input: bool = True) -> T.List[str]:
-        newvalue = self.listify(value, user_input)
+    def listify(self, value: T.Any) -> T.List[T.Any]:
+        return self.listify_value(value, self.split_args)
+
+    def validate_value(self, value: T.Union[str, T.List[str]]) -> T.List[str]:
+        newvalue = self.listify(value)
 
         if not self.allow_dups and len(set(newvalue)) != len(newvalue):
             msg = 'Duplicated values in array option is deprecated. ' \
@@ -324,6 +321,59 @@ class UserFeatureOption(UserComboOption):
     def is_auto(self) -> bool:
         return self.value == 'auto'
 
+class UserStdOption(UserComboOption):
+    '''
+    UserOption specific to c_std and cpp_std options. User can set a list of
+    STDs in preference order and it selects the first one supported by current
+    compiler.
+
+    For historical reasons, some compilers (msvc) allowed setting a GNU std and
+    silently fell back to C std. This is now deprecated. Projects that support
+    both GNU and MSVC compilers should set e.g. c_std=gnu11,c11.
+
+    This is not using self.deprecated mechanism we already have for project
+    options because we want to print a warning if ALL values are deprecated, not
+    if SOME values are deprecated.
+    '''
+    def __init__(self, lang: str, all_stds: T.List[str]) -> None:
+        self.lang = lang.lower()
+        self.all_stds = ['none'] + all_stds
+        # Map a deprecated std to its replacement. e.g. gnu11 -> c11.
+        self.deprecated_stds: T.Dict[str, str] = {}
+        super().__init__(f'{lang} language standard to use', ['none'], 'none')
+
+    def set_versions(self, versions: T.List[str], gnu: bool = False, gnu_deprecated: bool = False) -> None:
+        assert all(std in self.all_stds for std in versions)
+        self.choices += versions
+        if gnu:
+            gnu_stds_map = {f'gnu{std[1:]}': std for std in versions}
+            if gnu_deprecated:
+                self.deprecated_stds.update(gnu_stds_map)
+            else:
+                self.choices += gnu_stds_map.keys()
+
+    def validate_value(self, value: T.Union[str, T.List[str]]) -> str:
+        candidates = UserArrayOption.listify_value(value)
+        unknown = [std for std in candidates if std not in self.all_stds]
+        if unknown:
+            raise MesonException(f'Unknown {self.lang.upper()} std {unknown}. Possible values are {self.all_stds}.')
+        # Check first if any of the candidates are not deprecated
+        for std in candidates:
+            if std in self.choices:
+                return std
+        # Fallback to a deprecated std if any
+        for std in candidates:
+            newstd = self.deprecated_stds.get(std)
+            if newstd is not None:
+                mlog.deprecation(
+                    f'None of the values {candidates} are supported by the {self.lang} compiler.\n' +
+                    f'However, the deprecated {std} std currently falls back to {newstd}.\n' +
+                    'This will be an error in the future.\n' +
+                    'If the project supports both GNU and MSVC compilers, a value such as\n' +
+                    '"c_std=gnu11,c11" specifies that GNU is prefered but it can safely fallback to plain c11.')
+                return newstd
+        raise MesonException(f'None of values {candidates} are supported by the {self.lang.upper()} compiler. ' +
+                             f'Possible values are {self.choices}')
 
 class DependencyCacheType(enum.Enum):