eliminate build dependency on installed protoc, re-export prost::Message

candle-onnx/Cargo.toml

@@ -14,8 +14,9 @@ candle = { path = "../candle-core", package = "candle-core", version = "0.9.1" }
 candle-nn = { path = "../candle-nn", version = "0.9.1" }
 prost = "0.12.1"
 
-[build-dependencies]
-prost-build = "0.12.1"
+# [build-dependencies]
+# prost-build = "0.12.1"
+# protobuf-src = "2.1.1"
 
 [dev-dependencies]
 anyhow = { version = "1", features = ["backtrace"] }

candle-onnx/README.md

@@ -1,21 +1,3 @@
 # candle-onnx
 
 This crate adds ONNX support to candle
-
-## FAQ
-
-#### Missing protoc installation when compiling candle-onnx
-
-The candle-onnx dependency prost-build no longer comes bundled with prost
-binaries. This could cause the following error when attempting to compile
-candle-onnx:
-
-```
-error: failed to run custom build command for `candle-onnx`
-Caused by: // (...)
-  Could not find `protoc` installation and this build crate cannot proceed without this knowledge.
-```
-
-To fix this issue install protoc on your system and make it available in your
-system `PATH`. See the [protoc
-documentation](https://grpc.io/docs/protoc-installation/) for more information.

candle-onnx/build.rs

@@ -1,6 +1,7 @@
 use std::io::Result;
 
 fn main() -> Result<()> {
+    std::env::set_var("PROTOC", protobuf_src::protoc());
     prost_build::compile_protos(&["src/onnx.proto3"], &["src/"])?;
     Ok(())
 }

candle-onnx/src/lib.rs

@@ -1,4 +1,5 @@
 use candle::Result;
+pub use prost;
 use prost::Message;
 
 pub mod onnx {