Re: [PATCH v1 1/9] qapi: golang: Generate qapi's enum types in Go

[John Snow]

On Wed, Sep 27, 2023 at 7:25 AM Victor Toso <victortoso@redhat.com> wrote:
>
> This patch handles QAPI enum types and generates its equivalent in Go.
>
> Basically, Enums are being handled as strings in Golang.
>
> 1. For each QAPI enum, we will define a string type in Go to be the
>    assigned type of this specific enum.
>
> 2. Naming: CamelCase will be used in any identifier that we want to
>    export [0], which is everything.
>
> [0] https://go.dev/ref/spec#Exported_identifiers
>
> Example:
>
> qapi:
>   | { 'enum': 'DisplayProtocol',
>   |   'data': [ 'vnc', 'spice' ] }
>
> go:
>   | type DisplayProtocol string
>   |
>   | const (
>   |     DisplayProtocolVnc   DisplayProtocol = "vnc"
>   |     DisplayProtocolSpice DisplayProtocol = "spice"
>   | )
>
> Signed-off-by: Victor Toso <victortoso@redhat.com>
> ---
>  scripts/qapi/golang.py | 140 +++++++++++++++++++++++++++++++++++++++++
>  scripts/qapi/main.py   |   2 +
>  2 files changed, 142 insertions(+)
>  create mode 100644 scripts/qapi/golang.py
>
> diff --git a/scripts/qapi/golang.py b/scripts/qapi/golang.py
> new file mode 100644
> index 0000000000..87081cdd05
> --- /dev/null
> +++ b/scripts/qapi/golang.py
> @@ -0,0 +1,140 @@
> +"""
> +Golang QAPI generator
> +"""
> +# Copyright (c) 2023 Red Hat Inc.
> +#
> +# Authors:
> +#  Victor Toso <victortoso@redhat.com>
> +#
> +# This work is licensed under the terms of the GNU GPL, version 2.
> +# See the COPYING file in the top-level directory.
> +
> +# due QAPISchemaVisitor interface
> +# pylint: disable=too-many-arguments
> +
> +# Just for type hint on self
> +from __future__ import annotations
> +
> +import os
> +from typing import List, Optional
> +
> +from .schema import (
> +    QAPISchema,
> +    QAPISchemaType,
> +    QAPISchemaVisitor,
> +    QAPISchemaEnumMember,
> +    QAPISchemaFeature,
> +    QAPISchemaIfCond,
> +    QAPISchemaObjectType,
> +    QAPISchemaObjectTypeMember,
> +    QAPISchemaVariants,
> +)
> +from .source import QAPISourceInfo
> +
> +TEMPLATE_ENUM = '''
> +type {name} string
> +const (
> +{fields}
> +)
> +'''
> +
> +
> +def gen_golang(schema: QAPISchema,
> +               output_dir: str,
> +               prefix: str) -> None:
> +    vis = QAPISchemaGenGolangVisitor(prefix)
> +    schema.visit(vis)
> +    vis.write(output_dir)
> +
> +
> +def qapi_to_field_name_enum(name: str) -> str:
> +    return name.title().replace("-", "")
> +
> +
> +class QAPISchemaGenGolangVisitor(QAPISchemaVisitor):
> +
> +    def __init__(self, _: str):
> +        super().__init__()
> +        types = ["enum"]
> +        self.target = {name: "" for name in types}
> +        self.schema = None
> +        self.golang_package_name = "qapi"
> +
> +    def visit_begin(self, schema):
> +        self.schema = schema
> +
> +        # Every Go file needs to reference its package name
> +        for target in self.target:
> +            self.target[target] = f"package {self.golang_package_name}\n"
> +
> +    def visit_end(self):
> +        self.schema = None
> +
> +    def visit_object_type(self: QAPISchemaGenGolangVisitor,
> +                          name: str,
> +                          info: Optional[QAPISourceInfo],
> +                          ifcond: QAPISchemaIfCond,
> +                          features: List[QAPISchemaFeature],
> +                          base: Optional[QAPISchemaObjectType],
> +                          members: List[QAPISchemaObjectTypeMember],
> +                          variants: Optional[QAPISchemaVariants]
> +                          ) -> None:
> +        pass
> +
> +    def visit_alternate_type(self: QAPISchemaGenGolangVisitor,
> +                             name: str,
> +                             info: Optional[QAPISourceInfo],
> +                             ifcond: QAPISchemaIfCond,
> +                             features: List[QAPISchemaFeature],
> +                             variants: QAPISchemaVariants
> +                             ) -> None:
> +        pass
> +
> +    def visit_enum_type(self: QAPISchemaGenGolangVisitor,
> +                        name: str,
> +                        info: Optional[QAPISourceInfo],
> +                        ifcond: QAPISchemaIfCond,
> +                        features: List[QAPISchemaFeature],
> +                        members: List[QAPISchemaEnumMember],
> +                        prefix: Optional[str]
> +                        ) -> None:
> +
> +        value = qapi_to_field_name_enum(members[0].name)

Unsure if this was addressed on the mailing list yet, but in our call
we discussed how this call was vestigial and was causing the QAPI
tests to fail. Actually, I can't quite run "make check-qapi-schema"
and see the failure, I'm seeing it when I run "make check" and I'm not
sure how to find the failure more efficiently/quickly:

jsnow@scv ~/s/q/build (review)> make
[1/60] Generating subprojects/dtc/version_gen.h with a custom command
[2/60] Generating qemu-version.h with a custom command (wrapped by
meson to capture output)
[3/44] Generating tests/Test QAPI files with a custom command
FAILED: tests/qapi-builtin-types.c tests/qapi-builtin-types.h
tests/qapi-builtin-visit.c tests/qapi-builtin-visit.h
tests/test-qapi-commands-sub-sub-module.c
tests/test-qapi-commands-sub-sub-module.h tests/test-qapi-commands.c
tests/test-qapi-commands.h tests/test-qapi-emit-events.c
tests/test-qapi-emit-events.h tests/test-qapi-events-sub-sub-module.c
tests/test-qapi-events-sub-sub-module.h tests/test-qapi-events.c
tests/test-qapi-events.h tests/test-qapi-init-commands.c
tests/test-qapi-init-commands.h tests/test-qapi-introspect.c
tests/test-qapi-introspect.h tests/test-qapi-types-sub-sub-module.c
tests/test-qapi-types-sub-sub-module.h tests/test-qapi-types.c
tests/test-qapi-types.h tests/test-qapi-visit-sub-sub-module.c
tests/test-qapi-visit-sub-sub-module.h tests/test-qapi-visit.c
tests/test-qapi-visit.h
/home/jsnow/src/qemu/build/pyvenv/bin/python3
/home/jsnow/src/qemu/scripts/qapi-gen.py -o
/home/jsnow/src/qemu/build/tests -b -p test-
../tests/qapi-schema/qapi-schema-test.json --suppress-tracing
Traceback (most recent call last):
  File "/home/jsnow/src/qemu/scripts/qapi-gen.py", line 19, in <module>
    sys.exit(main.main())
             ^^^^^^^^^^^
  File "/home/jsnow/src/qemu/scripts/qapi/main.py", line 96, in main
    generate(args.schema,
  File "/home/jsnow/src/qemu/scripts/qapi/main.py", line 58, in generate
    gen_golang(schema, output_dir, prefix)
  File "/home/jsnow/src/qemu/scripts/qapi/golang.py", line 46, in gen_golang
    schema.visit(vis)
  File "/home/jsnow/src/qemu/scripts/qapi/schema.py", line 1227, in visit
    mod.visit(visitor)
  File "/home/jsnow/src/qemu/scripts/qapi/schema.py", line 209, in visit
    entity.visit(visitor)
  File "/home/jsnow/src/qemu/scripts/qapi/schema.py", line 346, in visit
    visitor.visit_enum_type(
  File "/home/jsnow/src/qemu/scripts/qapi/golang.py", line 102, in
visit_enum_type
    value = qapi_to_field_name_enum(members[0].name)
                                    ~~~~~~~^^^
IndexError: list index out of range
ninja: build stopped: subcommand failed.
make: *** [Makefile:162: run-ninja] Error 1


For the rest of my review, I commented this line out and continued on.

> +        fields = ""
> +        for member in members:
> +            value = qapi_to_field_name_enum(member.name)
> +            fields += f'''\t{name}{value} {name} = "{member.name}"\n'''
> +
> +        self.target["enum"] += TEMPLATE_ENUM.format(name=name, 
> fields=fields[:-1])
> +
> +    def visit_array_type(self, name, info, ifcond, element_type):
> +        pass
> +
> +    def visit_command(self,
> +                      name: str,
> +                      info: Optional[QAPISourceInfo],
> +                      ifcond: QAPISchemaIfCond,
> +                      features: List[QAPISchemaFeature],
> +                      arg_type: Optional[QAPISchemaObjectType],
> +                      ret_type: Optional[QAPISchemaType],
> +                      gen: bool,
> +                      success_response: bool,
> +                      boxed: bool,
> +                      allow_oob: bool,
> +                      allow_preconfig: bool,
> +                      coroutine: bool) -> None:
> +        pass
> +
> +    def visit_event(self, name, info, ifcond, features, arg_type, boxed):
> +        pass
> +
> +    def write(self, output_dir: str) -> None:
> +        for module_name, content in self.target.items():
> +            go_module = module_name + "s.go"
> +            go_dir = "go"
> +            pathname = os.path.join(output_dir, go_dir, go_module)
> +            odir = os.path.dirname(pathname)
> +            os.makedirs(odir, exist_ok=True)
> +
> +            with open(pathname, "w", encoding="ascii") as outfile:
> +                outfile.write(content)
> diff --git a/scripts/qapi/main.py b/scripts/qapi/main.py
> index 316736b6a2..cdbb3690fd 100644
> --- a/scripts/qapi/main.py
> +++ b/scripts/qapi/main.py
> @@ -15,6 +15,7 @@
>  from .common import must_match
>  from .error import QAPIError
>  from .events import gen_events
> +from .golang import gen_golang
>  from .introspect import gen_introspect
>  from .schema import QAPISchema
>  from .types import gen_types
> @@ -54,6 +55,7 @@ def generate(schema_file: str,
>      gen_events(schema, output_dir, prefix)
>      gen_introspect(schema, output_dir, prefix, unmask)
>
> +    gen_golang(schema, output_dir, prefix)
>
>  def main() -> int:
>      """
> --
> 2.41.0
>