[bazel] Correctly handle proto files under _virtual_imports

This can happen if:
  1. `proto_library` contains at least one of `import_prefix/strip_import_prefix`, or
  2. (for Bazel >= 1.0) at least one of `proto_library`'s `srcs` is generated.

Fixes #1094

examples/proto/examplepb/BUILD.bazel

@@ -4,20 +4,23 @@ load("@grpc_ecosystem_grpc_gateway//protoc-gen-swagger:defs.bzl", "protoc_gen_sw
 
 package(default_visibility = ["//visibility:public"])
 
+# TODO(yannic): Add examples/tests that use import_prefix/strip_import_prefix.
+
 # gazelle:exclude a_bit_of_everything.pb.gw.go
 # gazelle:exclude echo_service.pb.gw.go
 # gazelle:exclude flow_combination.pb.gw.go
+# gazelle:exclude generated_input.proto
 # gazelle:exclude non_standard_names.pb.gw.go
+# gazelle:exclude response_body_service.pb.gw.go
 # gazelle:exclude stream.pb.gw.go
 # gazelle:exclude use_go_template.pb.gw.go
 # gazelle:exclude wrappers.pb.gw.go
-# gazelle:exclude response_body_service.pb.gw.go
 
 genrule(
     name = "generated_proto",
     srcs = ["generated_input.proto"],
     outs = ["generated_output.proto"],
-    cmd = "cp $< $@", # A simple copy simulates a generated proto file.
+    cmd = "cp $< $@",  # A simple copy simulates a generated proto file.
 )
 
 proto_library(

protoc-gen-swagger/defs.bzl

@@ -4,133 +4,163 @@ Reads the the api spec in protobuf format and generate an open-api spec.
 Optionally applies settings from the grpc-service configuration.
 """
 
-def _collect_includes(gen_dir, srcs):
-    """Build an include path mapping.
-
-    It is important to not just collect unique dirnames, to also support
-    proto files of the same name from different packages.
-
-    The implementation below is similar to what bazel does in its
-    ProtoCompileActionBuilder.java
+# TODO(yannic): Replace with |proto_common.direct_source_infos| when
+# https://github.com/bazelbuild/rules_proto/pull/22 lands.
+def _direct_source_infos(proto_info, provided_sources = []):
+    """Returns sequence of `ProtoFileInfo` for `proto_info`'s direct sources.
+
+    Files that are both in `proto_info`'s direct sources and in
+    `provided_sources` are skipped. This is useful, e.g., for well-known
+    protos that are already provided by the Protobuf runtime.
+
+    Args:
+      proto_info: An instance of `ProtoInfo`.
+      provided_sources: Optional. A sequence of files to ignore.
+          Usually, these files are already provided by the
+          Protocol Buffer runtime (e.g. Well-Known protos).
+
+    Returns: A sequence of `ProtoFileInfo` containing information about
+        `proto_info`'s direct sources.
     """
-    includes = []
-    for src in srcs:
-        ref_path = src.path
 
-        if ref_path.startswith(gen_dir):
-            ref_path = ref_path[len(gen_dir):].lstrip("/")
+    source_root = proto_info.proto_source_root
+    if "." == source_root:
+        return [struct(file = src, import_path = src.path) for src in proto_info.direct_sources]
+
+    offset = len(source_root) + 1  # + '/'.
+
+    infos = []
+    for src in proto_info.direct_sources:
+        # TODO(yannic): Remove this hack when we drop support for Bazel < 1.0.
+        local_offset = offset
+        if src.root.path and not source_root.startswith(src.root.path):
+            # Before Bazel 1.0, `proto_source_root` wasn't guaranteed to be a
+            # prefix of `src.path`. This could happend, e.g., if `file` was
+            # generated (https://github.com/bazelbuild/bazel/issues/9215).
+            local_offset += len(src.root.path) + 1  # + '/'.
+        infos.append(struct(file = src, import_path = src.path[local_offset:]))
+
+    return infos
+
+def _run_proto_gen_swagger(
+        actions,
+        proto_info,
+        target_name,
+        transitive_proto_srcs,
+        protoc,
+        protoc_gen_swagger,
+        grpc_api_configuration,
+        single_output,
+        json_names_for_fields):
+    args = actions.args()
+
+    args.add("--plugin", "protoc-gen-swagger=%s" % protoc_gen_swagger.path)
+
+    args.add("--swagger_opt", "logtostderr=true")
+    args.add("--swagger_opt", "allow_repeated_fields_in_body=true")
+
+    extra_inputs = []
+    if grpc_api_configuration:
+        extra_inputs.append(grpc_api_configuration)
+        args.add("--swagger_opt", "grpc_api_configuration=%s" % grpc_api_configuration.path)
 
-        if src.owner.workspace_root:
-            workspace_root = src.owner.workspace_root
-            ref_path = ref_path[len(workspace_root):].lstrip("/")
+    if json_names_for_fields:
+        args.add("--swagger_opt", "json_names_for_fields=true")
 
-        include = ref_path + "=" + src.path
-        if include not in includes:
-            includes.append(include)
+    proto_file_infos = _direct_source_infos(proto_info)
 
-    return includes
+    # TODO(yannic): Use |proto_info.transitive_descriptor_sets| when
+    # https://github.com/bazelbuild/bazel/issues/9337 is fixed.
+    args.add_all(proto_info.transitive_proto_path, format_each = "--proto_path=%s")
 
-def _run_proto_gen_swagger(ctx, direct_proto_srcs, transitive_proto_srcs, actions, protoc, protoc_gen_swagger, grpc_api_configuration, single_output, json_names_for_fields):
-    swagger_files = []
+    if single_output:
+        args.add("--swagger_opt", "allow_merge=true")
+        args.add("--swagger_opt", "merge_file_name=%s" % target_name)
 
-    inputs = direct_proto_srcs + transitive_proto_srcs
-    tools = [protoc_gen_swagger]
+        swagger_file = actions.declare_file("%s.swagger.json" % target_name)
+        args.add("--swagger_out", swagger_file.dirname)
 
-    options = ["logtostderr=true", "allow_repeated_fields_in_body=true"]
-    if grpc_api_configuration:
-        options.append("grpc_api_configuration=%s" % grpc_api_configuration.path)
-        inputs.append(grpc_api_configuration)
+        args.add_all([f.import_path for f in proto_file_infos])
 
-    if json_names_for_fields:
-        options.append("json_names_for_fields=true")
+        actions.run(
+            executable = protoc,
+            tools = [protoc_gen_swagger],
+            inputs = depset(
+                direct = extra_inputs,
+                transitive = [transitive_proto_srcs],
+            ),
+            outputs = [swagger_file],
+            arguments = [args],
+        )
 
-    includes = _collect_includes(ctx.genfiles_dir.path, direct_proto_srcs + transitive_proto_srcs)
+        return [swagger_file]
 
-    if single_output:
+    # TODO(yannic): We may be able to generate all files in a single action,
+    # but that will change at least the semantics of `use_go_template.proto`.
+    swagger_files = []
+    for proto_file_info in proto_file_infos:
+        # TODO(yannic): This probably doesn't work as expected: we only add this
+        # option after we have seen it, so `.proto` sources that happen to be
+        # in the list of `.proto` files before `use_go_template.proto` will be
+        # compiled without this option, and all sources that get compiled after
+        # `use_go_template.proto` will have this option on.
+        if proto_file_info.file.basename == "use_go_template.proto":
+            args.add("--swagger_opt", "use_go_templates=true")
+
+        file_name = "%s.swagger.json" % proto_file_info.import_path[:-len(".proto")]
         swagger_file = actions.declare_file(
-            "%s.swagger.json" % ctx.attr.name,
-            sibling = direct_proto_srcs[0],
+            "_virtual_imports/%s/%s" % (target_name, file_name),
         )
-        output_dir = ctx.bin_dir.path
-        if direct_proto_srcs[0].owner.workspace_root:
-            output_dir = "/".join([output_dir, direct_proto_srcs[0].owner.workspace_root])
 
-        output_dir = "/".join([output_dir, direct_proto_srcs[0].dirname])
-        options.append("allow_merge=true")
-        options.append("merge_file_name=%s" % ctx.attr.name)
+        file_args = actions.args()
+
+        offset = len(file_name) + 1  # + '/'.
+        file_args.add("--swagger_out", swagger_file.path[:-offset])
 
-        args = actions.args()
-        args.add("--plugin=protoc-gen-swagger=%s" % protoc_gen_swagger.path)
-        args.add("--swagger_out=%s:%s" % (",".join(options), output_dir))
-        args.add_all(["-I%s" % include for include in includes])
-        args.add_all([src.path for src in direct_proto_srcs])
+        file_args.add(proto_file_info.import_path)
 
         actions.run(
             executable = protoc,
-            inputs = inputs,
-            tools = tools,
+            tools = [protoc_gen_swagger],
+            inputs = depset(
+                direct = extra_inputs,
+                transitive = [transitive_proto_srcs],
+            ),
             outputs = [swagger_file],
-            arguments = [args],
+            arguments = [args, file_args],
         )
-
         swagger_files.append(swagger_file)
-    else:
-        for proto in direct_proto_srcs:
-            if proto.basename == "use_go_template.proto":
-                options.append("use_go_templates=true")
-
-            swagger_file = actions.declare_file(
-                "%s.swagger.json" % proto.basename[:-len(".proto")],
-                sibling = proto,
-            )
-
-            output_dir = ctx.bin_dir.path
-            if proto.owner.workspace_root:
-                output_dir = "/".join([output_dir, proto.owner.workspace_root])
-
-            args = actions.args()
-            args.add("--plugin=protoc-gen-swagger=%s" % protoc_gen_swagger.path)
-            args.add("--swagger_out=%s:%s" % (",".join(options), output_dir))
-            args.add_all(["-I%s" % include for include in includes])
-            args.add(proto.path)
-
-            actions.run(
-                executable = protoc,
-                inputs = inputs,
-                tools = tools,
-                outputs = [swagger_file],
-                arguments = [args],
-            )
-            swagger_files.append(swagger_file)
 
     return swagger_files
 
 def _proto_gen_swagger_impl(ctx):
     proto = ctx.attr.proto[ProtoInfo]
-    grpc_api_configuration = ctx.file.grpc_api_configuration
-
-    return [DefaultInfo(
-        files = depset(
-            _run_proto_gen_swagger(
-                ctx,
-                direct_proto_srcs = proto.direct_sources,
-                transitive_proto_srcs = ctx.files._well_known_protos + proto.transitive_sources.to_list(),
-                actions = ctx.actions,
-                protoc = ctx.executable._protoc,
-                protoc_gen_swagger = ctx.executable._protoc_gen_swagger,
-                grpc_api_configuration = grpc_api_configuration,
-                single_output = ctx.attr.single_output,
-                json_names_for_fields = ctx.attr.json_names_for_fields,
+    return [
+        DefaultInfo(
+            files = depset(
+                _run_proto_gen_swagger(
+                    actions = ctx.actions,
+                    proto_info = proto,
+                    target_name = ctx.attr.name,
+                    transitive_proto_srcs = depset(
+                        direct = ctx.files._well_known_protos,
+                        transitive = [proto.transitive_sources],
+                    ),
+                    protoc = ctx.executable._protoc,
+                    protoc_gen_swagger = ctx.executable._protoc_gen_swagger,
+                    grpc_api_configuration = ctx.file.grpc_api_configuration,
+                    single_output = ctx.attr.single_output,
+                    json_names_for_fields = ctx.attr.json_names_for_fields,
+                ),
             ),
         ),
-    )]
+    ]
 
 protoc_gen_swagger = rule(
     attrs = {
         "proto": attr.label(
-            allow_rules = ["proto_library"],
             mandatory = True,
-            providers = ["proto"],
+            providers = [ProtoInfo],
         ),
         "grpc_api_configuration": attr.label(
             allow_single_file = True,