Updates to build system for upb C++ compiler.

BUILD

@@ -249,7 +249,7 @@ cc_test(
 
 upb_proto_library(
     name = "conformance_proto_upb",
-    upbc = ":upbc",
+    upbc = ":protoc-gen-upb",
     deps = [
         "@com_google_protobuf//:conformance_proto",
         "@com_google_protobuf//:test_messages_proto3_proto",
@@ -373,13 +373,33 @@ lua_test(
 # upb compiler #################################################################
 
 lua_binary(
-    name = "upbc",
+    name = "lua_upbc",
     luadeps = [
         "lua/upbc_lib",
     ],
     luamain = "tools/upbc.lua",
 )
 
+cc_library(
+    name = "upbc_generator",
+    hdrs = ["upbc/generator.h"],
+    srcs = ["upbc/generator.cc", "upbc/message_layout.h", "upbc/message_layout.cc"],
+    deps = [
+        "@com_google_protobuf//:protobuf",
+        "@com_google_protobuf//:protoc_lib",
+        "@absl//absl/strings",
+    ],
+)
+
+cc_binary(
+    name = "protoc-gen-upb",
+    srcs = ["upbc/main.cc"],
+    deps = [
+        ":upbc_generator",
+        "@com_google_protobuf//:protoc_lib",
+    ],
+)
+
 # Test the CMake build #########################################################
 
 make_shell_script(
@@ -394,6 +414,7 @@ sh_test(
     data = glob([
         "CMakeLists.txt",
         "google/**/*",
+        "upbc/**/*",
         "upb/**/*",
         "tests/**/*",
     ]) + [
@@ -458,8 +479,8 @@ genrule(
         "generated/upb/descriptor/descriptor.upbdefs.h",
         "generated/upb/descriptor/descriptor.upbdefs.c",
     ],
-    cmd = "UPBC=$$PWD/$(location :upbc); INFILE=$$PWD/$<; cd $(GENDIR)/generated && $$UPBC --generate-upbdefs $$INFILE",
-    tools = [":upbc"],
+    cmd = "UPBC=$$PWD/$(location :lua_upbc); INFILE=$$PWD/$<; cd $(GENDIR)/generated && $$UPBC --generate-upbdefs $$INFILE",
+    tools = [":lua_upbc"],
 )
 
 proto_library(
@@ -478,13 +499,16 @@ genrule(
 
 genrule(
     name = "generate_descriptor_c",
-    srcs = ["generated/google/protobuf/descriptor.pb"],
+    srcs = ["google/protobuf/descriptor.proto"],
     outs = [
         "generated/google/protobuf/descriptor.upb.h",
         "generated/google/protobuf/descriptor.upb.c",
     ],
-    cmd = "UPBC=$$PWD/$(location :upbc); INFILE=$$PWD/$<; cd $(GENDIR)/generated && $$UPBC $$INFILE",
-    tools = [":upbc"],
+    cmd = "$(location @com_google_protobuf//:protoc) $< --upb_out=$(GENDIR)/generated --plugin=protoc-gen-upb=$(location :protoc-gen-upb)",
+    tools = [
+        "@com_google_protobuf//:protoc",
+        ":protoc-gen-upb"
+    ],
 )
 
 proto_library(
@@ -506,8 +530,8 @@ genrule(
         "generated/tests/json/test.upbdefs.h",
         "generated/tests/json/test.upbdefs.c",
     ],
-    cmd = "UPBC=$$PWD/$(location :upbc); INFILE=$$PWD/$<; cd $(GENDIR)/generated && $$UPBC --generate-upbdefs $$INFILE",
-    tools = [":upbc"],
+    cmd = "UPBC=$$PWD/$(location :lua_upbc); INFILE=$$PWD/$<; cd $(GENDIR)/generated && $$UPBC --generate-upbdefs $$INFILE",
+    tools = [":lua_upbc"],
 )
 
 genrule(

WORKSPACE

@@ -23,6 +23,12 @@ git_repository(
     #tag = "conformance-build-tag",
 )
 
+git_repository(
+    name = "absl",
+    commit = "070f6e47b33a2909d039e620c873204f78809492",
+    remote = "https://github.com/abseil/abseil-cpp.git",
+)
+
 http_archive(
     name = "ragel",
     sha256 = "5f156edb65d20b856d638dd9ee2dfb43285914d9aa2b6ec779dac0270cd56c3f",

build_defs.bzl

@@ -218,31 +218,26 @@ def _remove_up(string):
     return _remove_suffix(string, ".proto")
 
 def _upb_proto_library_srcs_impl(ctx):
-    descriptors = []
+    sources = []
     outs = []
+    include_dirs = {}
     for dep in ctx.attr.deps:
         if hasattr(dep, 'proto'):
-            for desc in dep.proto.transitive_descriptor_sets:
-                descriptors.append(desc)
             for src in dep.proto.transitive_sources:
+                sources.append(src)
+                include_dirs[_remove_suffix(src.path, _remove_up(src.short_path) + "." + src.extension)] = True
                 outs.append(ctx.actions.declare_file(_remove_up(src.short_path) + ".upb.h"))
                 outs.append(ctx.actions.declare_file(_remove_up(src.short_path) + ".upb.c"))
                 outdir = _remove_suffix(outs[-1].path, _remove_up(src.short_path) + ".upb.c")
 
-    concatenated = ctx.actions.declare_file(ctx.label.name + "_concatenated_descriptor.bin")
-    descriptor_paths = [d.path for d in descriptors]
+    source_paths = [d.path for d in sources]
+    include_args = ["-I" + root for root in include_dirs.keys()]
 
-    ctx.actions.run_shell(
-        inputs = descriptors,
-        outputs = [concatenated],
-        progress_message = "Concatenating descriptors",
-        command = "cat %s > %s" % (" ".join(descriptor_paths), concatenated.path),
-    )
     ctx.actions.run(
-        inputs = [concatenated],
+        inputs = [ctx.executable.upbc] + sources,
         outputs = outs,
-        executable = ctx.executable.upbc,
-        arguments = ["--outdir", outdir, concatenated.path],
+        executable = ctx.executable.protoc,
+        arguments = ["--upb_out", outdir, "--plugin=protoc-gen-upb=" + ctx.executable.upbc.path] + include_args + source_paths,
         progress_message = "Generating upb protos",
     )
 
@@ -255,6 +250,11 @@ _upb_proto_library_srcs = rule(
             executable = True,
             cfg = "host",
         ),
+        "protoc": attr.label(
+            executable = True,
+            cfg = "host",
+            default = "@com_google_protobuf//:protoc",
+        ),
         "deps": attr.label_list(),
     }
 )

tools/make_cmakelists.py

@@ -34,7 +34,7 @@ class BuildFileFunctions(object):
     pass
 
   def cc_library(self, **kwargs):
-    if kwargs["name"] == "amalgamation":
+    if kwargs["name"] == "amalgamation" or kwargs["name"] == "upbc_generator":
       return
     files = kwargs.get("srcs", []) + kwargs.get("hdrs", [])
     self.converter.toplevel += "add_library(%s\n  %s)\n" % (