qapi: Replace List[str] with Sequence[str] for ifcond

It does happen to be a list (as of now), but we can describe it in more
general terms with no loss in accuracy to allow tuples and other
constructs.

In the future, we can write "ifcond: Sequence[str] = ()" as a default
parameter, which we could not do safely with a Mutable type like a List.

Signed-off-by: John Snow <jsnow@redhat.com>
Message-Id: <20210216021809.134886-2-jsnow@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
[Commit message tweaked]
Signed-off-by: Markus Armbruster <armbru@redhat.com>

5 files changed, 21 insertions, 20 deletions

diff --git a/scripts/qapi/commands.py b/scripts/qapi/commands.py
index 54af519f44..0a75a9371b 100644
--- a/scripts/qapi/commands.py
+++ b/scripts/qapi/commands.py
@@ -17,6 +17,7 @@ from typing import (
     Dict,
     List,
     Optional,
+    Sequence,
     Set,
 )
 
@@ -297,7 +298,7 @@ void %(c_prefix)sqmp_init_marshal(QmpCommandList *cmds)
     def visit_command(self,
                       name: str,
                       info: Optional[QAPISourceInfo],
-                      ifcond: List[str],
+                      ifcond: Sequence[str],
                       features: List[QAPISchemaFeature],
                       arg_type: Optional[QAPISchemaObjectType],
                       ret_type: Optional[QAPISchemaType],
diff --git a/scripts/qapi/events.py b/scripts/qapi/events.py
index 8c57deb2b8..90d2f6156d 100644
--- a/scripts/qapi/events.py
+++ b/scripts/qapi/events.py
@@ -12,7 +12,7 @@ This work is licensed under the terms of the GNU GPL, version 2.
 See the COPYING file in the top-level directory.
 """
 
-from typing import List, Optional
+from typing import List, Optional, Sequence
 
 from .common import c_enum_const, c_name, mcgen
 from .gen import QAPISchemaModularCVisitor, build_params, ifcontext
@@ -214,7 +214,7 @@ void %(event_emit)s(%(event_enum)s event, QDict *qdict);
     def visit_event(self,
                     name: str,
                     info: Optional[QAPISourceInfo],
-                    ifcond: List[str],
+                    ifcond: Sequence[str],
                     features: List[QAPISchemaFeature],
                     arg_type: Optional[QAPISchemaObjectType],
                     boxed: bool) -> None:
diff --git a/scripts/qapi/gen.py b/scripts/qapi/gen.py
index 63549cc8d4..1fa503bdbd 100644
--- a/scripts/qapi/gen.py
+++ b/scripts/qapi/gen.py
@@ -17,8 +17,8 @@ import re
 from typing import (
     Dict,
     Iterator,
-    List,
     Optional,
+    Sequence,
     Tuple,
 )
 
@@ -85,7 +85,7 @@ class QAPIGen:
                 fp.write(text)
 
 
-def _wrap_ifcond(ifcond: List[str], before: str, after: str) -> str:
+def _wrap_ifcond(ifcond: Sequence[str], before: str, after: str) -> str:
     if before == after:
         return after   # suppress empty #if ... #endif
 
@@ -127,9 +127,9 @@ def build_params(arg_type: Optional[QAPISchemaObjectType],
 class QAPIGenCCode(QAPIGen):
     def __init__(self, fname: str):
         super().__init__(fname)
-        self._start_if: Optional[Tuple[List[str], str, str]] = None
+        self._start_if: Optional[Tuple[Sequence[str], str, str]] = None
 
-    def start_if(self, ifcond: List[str]) -> None:
+    def start_if(self, ifcond: Sequence[str]) -> None:
         assert self._start_if is None
         self._start_if = (ifcond, self._body, self._preamble)
 
@@ -187,11 +187,11 @@ class QAPIGenH(QAPIGenC):
 
 
 @contextmanager
-def ifcontext(ifcond: List[str], *args: QAPIGenCCode) -> Iterator[None]:
+def ifcontext(ifcond: Sequence[str], *args: QAPIGenCCode) -> Iterator[None]:
     """
     A with-statement context manager that wraps with `start_if()` / `end_if()`.
 
-    :param ifcond: A list of conditionals, passed to `start_if()`.
+    :param ifcond: A sequence of conditionals, passed to `start_if()`.
     :param args: any number of `QAPIGenCCode`.
 
     Example::
diff --git a/scripts/qapi/types.py b/scripts/qapi/types.py
index 2bdd626847..20d572a23a 100644
--- a/scripts/qapi/types.py
+++ b/scripts/qapi/types.py
@@ -13,7 +13,7 @@ This work is licensed under the terms of the GNU GPL, version 2.
 # See the COPYING file in the top-level directory.
 """
 
-from typing import List, Optional
+from typing import List, Optional, Sequence
 
 from .common import (
     c_enum_const,
@@ -139,7 +139,7 @@ def gen_struct_members(members: List[QAPISchemaObjectTypeMember]) -> str:
     return ret
 
 
-def gen_object(name: str, ifcond: List[str],
+def gen_object(name: str, ifcond: Sequence[str],
                base: Optional[QAPISchemaObjectType],
                members: List[QAPISchemaObjectTypeMember],
                variants: Optional[QAPISchemaVariants]) -> str:
@@ -307,7 +307,7 @@ class QAPISchemaGenTypeVisitor(QAPISchemaModularCVisitor):
     def visit_enum_type(self,
                         name: str,
                         info: Optional[QAPISourceInfo],
-                        ifcond: List[str],
+                        ifcond: Sequence[str],
                         features: List[QAPISchemaFeature],
                         members: List[QAPISchemaEnumMember],
                         prefix: Optional[str]) -> None:
@@ -318,7 +318,7 @@ class QAPISchemaGenTypeVisitor(QAPISchemaModularCVisitor):
     def visit_array_type(self,
                          name: str,
                          info: Optional[QAPISourceInfo],
-                         ifcond: List[str],
+                         ifcond: Sequence[str],
                          element_type: QAPISchemaType) -> None:
         with ifcontext(ifcond, self._genh, self._genc):
             self._genh.preamble_add(gen_fwd_object_or_array(name))
@@ -328,7 +328,7 @@ class QAPISchemaGenTypeVisitor(QAPISchemaModularCVisitor):
     def visit_object_type(self,
                           name: str,
                           info: Optional[QAPISourceInfo],
-                          ifcond: List[str],
+                          ifcond: Sequence[str],
                           features: List[QAPISchemaFeature],
                           base: Optional[QAPISchemaObjectType],
                           members: List[QAPISchemaObjectTypeMember],
@@ -351,7 +351,7 @@ class QAPISchemaGenTypeVisitor(QAPISchemaModularCVisitor):
     def visit_alternate_type(self,
                              name: str,
                              info: Optional[QAPISourceInfo],
-                             ifcond: List[str],
+                             ifcond: Sequence[str],
                              features: List[QAPISchemaFeature],
                              variants: QAPISchemaVariants) -> None:
         with ifcontext(ifcond, self._genh):
diff --git a/scripts/qapi/visit.py b/scripts/qapi/visit.py
index 22e62df901..9aa0b1e11e 100644
--- a/scripts/qapi/visit.py
+++ b/scripts/qapi/visit.py
@@ -13,7 +13,7 @@ This work is licensed under the terms of the GNU GPL, version 2.
 See the COPYING file in the top-level directory.
 """
 
-from typing import List, Optional
+from typing import List, Optional, Sequence
 
 from .common import (
     c_enum_const,
@@ -337,7 +337,7 @@ class QAPISchemaGenVisitVisitor(QAPISchemaModularCVisitor):
     def visit_enum_type(self,
                         name: str,
                         info: Optional[QAPISourceInfo],
-                        ifcond: List[str],
+                        ifcond: Sequence[str],
                         features: List[QAPISchemaFeature],
                         members: List[QAPISchemaEnumMember],
                         prefix: Optional[str]) -> None:
@@ -348,7 +348,7 @@ class QAPISchemaGenVisitVisitor(QAPISchemaModularCVisitor):
     def visit_array_type(self,
                          name: str,
                          info: Optional[QAPISourceInfo],
-                         ifcond: List[str],
+                         ifcond: Sequence[str],
                          element_type: QAPISchemaType) -> None:
         with ifcontext(ifcond, self._genh, self._genc):
             self._genh.add(gen_visit_decl(name))
@@ -357,7 +357,7 @@ class QAPISchemaGenVisitVisitor(QAPISchemaModularCVisitor):
     def visit_object_type(self,
                           name: str,
                           info: Optional[QAPISourceInfo],
-                          ifcond: List[str],
+                          ifcond: Sequence[str],
                           features: List[QAPISchemaFeature],
                           base: Optional[QAPISchemaObjectType],
                           members: List[QAPISchemaObjectTypeMember],
@@ -379,7 +379,7 @@ class QAPISchemaGenVisitVisitor(QAPISchemaModularCVisitor):
     def visit_alternate_type(self,
                              name: str,
                              info: Optional[QAPISourceInfo],
-                             ifcond: List[str],
+                             ifcond: Sequence[str],
                              features: List[QAPISchemaFeature],
                              variants: QAPISchemaVariants) -> None:
         with ifcontext(ifcond, self._genh, self._genc):