This makes the file layout a bit more consistent with the `protos ->
protos_generator` pattern. I also replaced the `upbc` namespace with
`upb::generator`.
PiperOrigin-RevId: 569264372
This separate helper for upb dependencies no longer makes sense now that upb
has been merged into the protobuf repo. This change deletes that helper and
moves the upb-specific dependencies into the `protobuf_deps()` function.
I noticed that the Python package deps need to be updated to reflect our
current support level, but I will fix that in a followup CL.
PiperOrigin-RevId: 568997625
This change moves almost everything in the `upb/` directory up one level, so
that for example `upb/upb/generated_code_support.h` becomes just
`upb/generated_code_support.h`. The only exceptions I made to this were that I
left `upb/cmake` and `upb/BUILD` where they are, mostly because that avoids
conflict with other files and the current locations seem reasonable for now.
The `python/` directory is a little bit of a challenge because we had to merge
the existing directory there with `upb/python/`. I made `upb/python/BUILD` into
the BUILD file for the merged directory, and it effectively loads the contents
of the other BUILD file via `python/build_targets.bzl`, but I plan to clean
this up soon.
PiperOrigin-RevId: 568651768
If there is no local Python installation then the contents of this glob will be
empty. We want the build to succeed in that scenario, so this change will allow
that to happen.
PiperOrigin-RevId: 559407373
This flag was added to Protobuf and submitted separately due to version skew between repos.
This attempts to fix the following error from local and release settings both matching.
```
ERROR: /workspace/_build/out/external/upb/python/dist/BUILD.bazel:251:9: Illegal ambiguous match on configurable attribute "platform" in @upb//python/dist:binary_wheel:
@upb//python/dist:linux_x86_64_local
@upb//python/dist:windows_x86_64
Multiple matches are not allowed unless one is unambiguously more specialized or they resolve to the same value. See https://bazel.build/reference/be/functions#select.
```
PiperOrigin-RevId: 553226261
This special `proto_library` behavior is known as an *alias library*:
https://bazel.build/reference/be/protocol-buffer#proto_library_args
Without this CL, the compilation of the added test fails with:
```
test_import_empty_srcs.upb.c:12:10: error:
module :test_import_empty_srcs_proto.upb does not depend on a
module exporting 'test.upb.h'
```
PiperOrigin-RevId: 545153380
This fixes cases where the interpreter cannot be executed, as there is no indication about how to execute it.
Fixes#1212Closes#1336
COPYBARA_INTEGRATE_REVIEW=https://github.com/protocolbuffers/upb/pull/1336 from vthib:1212-python-interpreter-shebang 956482d9665c15f4781b16d7fa3da45a6615aa54
PiperOrigin-RevId: 541927182
"Thunks" are .c files with definitions for the inline functions in the gencode C
API. They are meant to be used from statically compiled languages that cannot
use inline C functions such as Rust.
Experimental, do not use. Our current plan is to delete this code in the order
of months. Without any prior warning.
PiperOrigin-RevId: 516522823
This was already broken, but wasn't caught in tests because `python3` wasn't defined on our windows machines. To prevent it from breaking the entire downstream Bazel workspace when `python3` exists, we mark it unsupported.
PiperOrigin-RevId: 506318286
This CL changes the upb compiler to no longer depend on C++ protobuf libraries. upb now uses its own reflection libraries to implement its code generator.
# Key Benefits
1. upb can now use its own reflection libraries throughout the compiler. This makes upb more consistent and principled, and gives us more chances to dogfood our own C++ reflection API. This highlighted several parts of the C++ reflection API that were incomplete.
2. This CL removes code duplication that previously existed in the compiler. The upb reflection library has code to build MiniDescriptors and MiniTables out of descriptors, but prior to this CL the upb compiler could not use it. The upb compiler had a separate copy of this logic, and the compiler's copy of this logic was especially tricky and hard to maintain. This CL removes the separate copy of that logic.
3. This CL (mostly) removes upb's dependency on the C++ protobuf library. We still depend on `protoc` (the binary), but the runtime and compiler no longer link against C++'s libraries. This opens up the possibility of speeding up some builds significantly if we can use a prebuilt `protoc` binary.
# Bootstrap Stages
To bootstrap, we check in a copy of our generated code for `descriptor.proto` and `plugin.proto`. This allows the compiler to depend on the generated code for these two protos without creating a circular dependency. This code is checked in to the `stage0` directory.
The bootstrapping process is divided into a few stages. All `cc_library()`, `upb_proto_library()`, and `cc_binary()` targets that would otherwise be circular participate in this staging process. That currently includes:
* `//third_party/upb:descriptor_upb_proto`
* `//third_party/upb:plugin_upb_proto`
* `//third_party/upb:reflection`
* `//third_party/upb:reflection_internal`
* `//third_party/upbc:common`
* `//third_party/upbc:file_layout`
* `//third_party/upbc:plugin`
* `//third_party/upbc:protoc-gen-upb`
For each of these targets, we produce a rule for each stage (the logic for this is nicely encapsulated in Blaze/Bazel macros like `bootstrap_cc_library()` and `bootstrap_upb_proto_library()`, so the `BUILD` file remains readable). For example:
* `//third_party/upb:descriptor_upb_proto_stage0`
* `//third_party/upb:descriptor_upb_proto_stage1`
* `//third_party/upb:descriptor_upb_proto`
The stages are:
1. `stage0`: This uses the checked-in version of the generated code. The stage0 compiler is correct and outputs the same code as all other compilers, but it is unnecessarily slow because its protos were compiled in bootstrap mode. The stage0 compiler is used to generate protos for stage1.
2. `stage1`: The stage1 compiler is correct and fast, and therefore we use it in almost all cases (eg. `upb_proto_library()`). However its own protos were not generated using `upb_proto_library()`, so its `cc_library()` targets cannot be safely mixed with `upb_proto_library()`, as this would lead to duplicate symbols.
3. final (no stage): The final compiler is identical to the `stage1` compiler. The only difference is that its protos were built with `upb_proto_library()`. This doesn't matter very much for the compiler binary, but for the `cc_library()` targets like `//third_party/upb:reflection`, only the final targets can be safely linked in by other applications.
# "Bootstrap Mode" Protos
The checked-in generated code is generated in a special "bootstrap" mode that is a bit different than normal generated code. Bootstrap mode avoids depending on the internal representation of MiniTables or the messages, at the cost of slower runtime performance.
Bootstrap mode only interacts with MiniTables and messages using public APIs such as `upb_MiniTable_Build()`, `upb_Message_GetInt32()`, etc. This is very important as it allows us to change the internal representation without needing to regenerate our bootstrap protos. This will make it far easier to write CLs that change the internal representation, because it avoids the awkward dance of trying to regenerate the bootstrap protos when the compiler itself is broken due to bootstrap protos being out of date.
The bootstrap generated code does have two downsides:
1. The accessors are less efficient, because they look up MiniTable fields by number instead of hard-coding the MiniTableField into the generated code.
2. It requires runtime initialization of the MiniTables, which costs CPU cycles at startup, and also allocates memory which is never freed. Per google3 rules this is not really a leak, since this memory is still reachable via static variables, but it is undesirable in many contexts. We could fix this part by introducing the equivalent of `google::protobuf::ShutdownProtobufLibrary()`).
These downsides are fine for the bootstrapping process, but they are reason enough not to enable bootstrap mode in general for all protos.
# Bootstrapping Always Uses OSS Protos
To enable smooth syncing between Google3 and OSS, we always use an OSS version of the checked in generated code for `stage0`, even in google3.
This requires that the google3 code can be switched to reference the OSS proto names using a preprocessor define. We introduce the `UPB_DESC(xyz)` macro for this, which will expand into either `proto2_xyz` or `google_protobuf_xyz`. Any libraries used in `stage0` must use `UPB_DESC(xyz)` rather than refer to the symbol names directly.
PiperOrigin-RevId: 501458451
This simplifies the code generation by making output agnostic to whether fasttables will be used or not.
This grows the generated code in the common case, but when fasttables are not being used the preprocessor will strip away the unused tables.
PiperOrigin-RevId: 499340805
Adam Cozzette
Joshua Haberman
Richard Levasseur
Sandy Zhang
Nevena Kotlaja
Mike Kruskal
Protobuf Team Bot
Vincent Thiberville
Jie Luo
Deanna Garcia
Thomas Van Lenten
Marcel Hlopko