Split cxx runtime and build components

.travis.yml

@@ -20,15 +20,15 @@ matrix:
       rust: nightly-x86_64-pc-windows-gnu
       before_script:
         # windows is bad at symlinks
-        - rm cmd/src/gen cmd/src/syntax gen/include macro/src/syntax src/gen src/syntax
-        - cp -r include gen; cp -r gen cmd/src; cp -r syntax cmd/src; cp -r syntax macro/src; cp -r gen src; cp -r syntax src
+        - rm gen/build/src/gen gen/build/src/syntax gen/cmd/src/gen gen/cmd/src/syntax gen/src/include macro/src/syntax
+        - cp -r include gen/src; cp -r gen/src gen/build/src/gen; cp -r gen/src gen/cmd/src/gen; cp -r syntax gen/build/src; cp -r syntax gen/cmd/src; cp -r syntax macro/src
 
     - name: Windows (msvc)
       os: windows
       rust: nightly-x86_64-pc-windows-msvc
       before_script:
-        - rm cmd/src/gen cmd/src/syntax gen/include macro/src/syntax src/gen src/syntax
-        - cp -r include gen; cp -r gen cmd/src; cp -r syntax cmd/src; cp -r syntax macro/src; cp -r gen src; cp -r syntax src
+        - rm gen/build/src/gen gen/build/src/syntax gen/cmd/src/gen gen/cmd/src/syntax gen/src/include macro/src/syntax
+        - cp -r include gen/src; cp -r gen/src gen/build/src/gen; cp -r gen/src gen/cmd/src/gen; cp -r syntax gen/build/src; cp -r syntax gen/cmd/src; cp -r syntax macro/src
 
     - name: Buck
       rust: nightly

BUCK

@@ -5,19 +5,13 @@ rust_library(
     deps = [
         ":core",
         ":macro",
-        "//third-party:anyhow",
-        "//third-party:cc",
-        "//third-party:codespan-reporting",
         "//third-party:link-cplusplus",
-        "//third-party:proc-macro2",
-        "//third-party:quote",
-        "//third-party:syn",
     ],
 )
 
 rust_binary(
     name = "codegen",
-    srcs = glob(["cmd/src/**"]),
+    srcs = glob(["gen/cmd/src/**"]),
     crate = "cxxbridge",
     visibility = ["PUBLIC"],
     deps = [
@@ -52,3 +46,17 @@ rust_library(
         "//third-party:syn",
     ],
 )
+
+rust_library(
+    name = "build",
+    srcs = glob(["gen/build/src/**"]),
+    visibility = ["PUBLIC"],
+    deps = [
+        "//third-party:anyhow",
+        "//third-party:cc",
+        "//third-party:codespan-reporting",
+        "//third-party:proc-macro2",
+        "//third-party:quote",
+        "//third-party:syn",
+    ],
+)

BUILD

@@ -3,25 +3,18 @@ load("//tools/bazel:rust.bzl", "rust_binary", "rust_library")
 rust_library(
     name = "cxx",
     srcs = glob(["src/**/*.rs"]),
-    data = ["src/gen/include/cxx.h"],
     visibility = ["//visibility:public"],
     deps = [
         ":core-lib",
         ":cxxbridge-macro",
-        "//third-party:anyhow",
-        "//third-party:cc",
-        "//third-party:codespan-reporting",
         "//third-party:link-cplusplus",
-        "//third-party:proc-macro2",
-        "//third-party:quote",
-        "//third-party:syn",
     ],
 )
 
 rust_binary(
     name = "codegen",
-    srcs = glob(["cmd/src/**/*.rs"]),
-    data = ["cmd/src/gen/include/cxx.h"],
+    srcs = glob(["gen/cmd/src/**/*.rs"]),
+    data = ["gen/cmd/src/gen/include/cxx.h"],
     visibility = ["//visibility:public"],
     deps = [
         "//third-party:anyhow",
@@ -57,3 +50,18 @@ rust_library(
         "//third-party:syn",
     ],
 )
+
+rust_library(
+    name = "build",
+    srcs = glob(["gen/build/src/**/*.rs"]),
+    data = ["gen/build/src/gen/include/cxx.h"],
+    visibility = ["//visibility:public"],
+    deps = [
+        "//third-party:anyhow",
+        "//third-party:cc",
+        "//third-party:codespan-reporting",
+        "//third-party:proc-macro2",
+        "//third-party:quote",
+        "//third-party:syn",
+    ],
+)

Cargo.toml

@@ -15,25 +15,20 @@ exclude = ["/demo-cxx", "/gen", "/syntax", "/third-party"]
 travis-ci = { repository = "dtolnay/cxx" }
 
 [dependencies]
-anyhow = "1.0"
-cc = "1.0.49"
-codespan-reporting = "0.9"
 cxxbridge-macro = { version = "=0.2.12", path = "macro" }
 link-cplusplus = "1.0"
-proc-macro2 = { version = "1.0", features = ["span-locations"] }
-quote = "1.0"
-syn = { version = "1.0", features = ["full"] }
 
 [build-dependencies]
 cc = "1.0.49"
 
 [dev-dependencies]
+cxx-build = { version = "=0.2.12", path = "gen/build" }
 cxx-test-suite = { version = "0", path = "tests/ffi" }
 rustversion = "1.0"
 trybuild = { version = "1.0.21", features = ["diff"] }
 
 [workspace]
-members = ["cmd", "demo-rs", "macro", "tests/ffi"]
+members = ["demo-rs", "gen/build", "gen/cmd", "macro", "tests/ffi"]
 
 [package.metadata.docs.rs]
 targets = ["x86_64-unknown-linux-gnu"]

README.md

@@ -219,8 +219,7 @@ set up any additional source files and compiler flags as normal.
 // build.rs
 
 fn main() {
-    cxx::Build::new()
-        .bridge("src/main.rs")  // returns a cc::Build
+    cxx_build::bridge("src/main.rs")  // returns a cc::Build
         .file("../demo-cxx/demo.cc")
         .flag("-std=c++11")
         .compile("cxxbridge-demo");

demo-rs/Cargo.toml

@@ -9,4 +9,4 @@ publish = false
 cxx = { path = ".." }
 
 [build-dependencies]
-cxx = { path = ".." }
+cxx-build = { path = "../gen/build" }

demo-rs/build.rs

@@ -1,6 +1,5 @@
 fn main() {
-    cxx::Build::new()
-        .bridge("src/main.rs")
+    cxx_build::bridge("src/main.rs")
         .file("../demo-cxx/demo.cc")
         .flag("-std=c++11")
         .compile("cxxbridge-demo");

gen/README.md

@@ -0,0 +1,4 @@
+This directory contains CXX's C++ code generator. This code generator has two
+public frontends, one a command-line application (binary) in the *cmd* directory
+and the other a library intended to be used from a build.rs in the *build*
+directory.

gen/build/Cargo.toml

@@ -0,0 +1,22 @@
+[package]
+name = "cxx-build"
+version = "0.2.12"
+authors = ["David Tolnay <dtolnay@gmail.com>"]
+edition = "2018"
+license = "MIT OR Apache-2.0"
+description = "C++ code generator for integrating `cxx` crate into a Cargo build."
+repository = "https://github.com/dtolnay/cxx"
+
+[badges]
+travis-ci = { repository = "dtolnay/cxx" }
+
+[dependencies]
+anyhow = "1.0"
+cc = "1.0.49"
+codespan-reporting = "0.9"
+proc-macro2 = { version = "1.0", features = ["span-locations"] }
+quote = "1.0"
+syn = { version = "1.0", features = ["full"] }
+
+[package.metadata.docs.rs]
+targets = ["x86_64-unknown-linux-gnu"]

gen/build/LICENSE-APACHE

@@ -0,0 +1 @@
+../../LICENSE-APACHE

gen/build/LICENSE-MIT

@@ -0,0 +1 @@
+../../LICENSE-MIT

gen/build/src/gen

@@ -0,0 +1 @@
+../../src

gen/build/src/lib.rs

@@ -0,0 +1,96 @@
+//! The CXX code generator for constructing and compiling C++ code.
+//!
+//! This is intended to be used from Cargo build scripts to execute CXX's
+//! C++ code generator, set up any additional compiler flags depending on
+//! the use case, and make the C++ compiler invocation.
+//!
+//! <br>
+//!
+//! # Example
+//!
+//! Example of a canonical Cargo build script that builds a CXX bridge:
+//!
+//! ```no_run
+//! // build.rs
+//!
+//! fn main() {
+//!     cxx_build::bridge("src/main.rs")
+//!         .file("../demo-cxx/demo.cc")
+//!         .flag("-std=c++11")
+//!         .compile("cxxbridge-demo");
+//!
+//!     println!("cargo:rerun-if-changed=src/main.rs");
+//!     println!("cargo:rerun-if-changed=../demo-cxx/demo.h");
+//!     println!("cargo:rerun-if-changed=../demo-cxx/demo.cc");
+//! }
+//! ```
+//!
+//! A runnable working setup with this build script is shown in the
+//! *demo-rs* and *demo-cxx* directories of [https://github.com/dtolnay/cxx].
+//!
+//! [https://github.com/dtolnay/cxx]: https://github.com/dtolnay/cxx
+//!
+//! <br>
+//!
+//! # Alternatives
+//!
+//! For use in non-Cargo builds like Bazel or Buck, CXX provides an
+//! alternate way of invoking the C++ code generator as a standalone command
+//! line tool. The tool is packaged as the `cxxbridge-cmd` crate.
+//!
+//! ```bash
+//! $ cargo install cxxbridge-cmd  # or build it from the repo
+//!
+//! $ cxxbridge src/main.rs --header > path/to/mybridge.h
+//! $ cxxbridge src/main.rs > path/to/mybridge.cc
+//! ```
+
+mod error;
+mod gen;
+mod paths;
+mod syntax;
+
+use crate::error::Result;
+use crate::gen::Opt;
+use anyhow::anyhow;
+use std::fs;
+use std::io::{self, Write};
+use std::path::Path;
+use std::process;
+
+/// This returns a [`cc::Build`] on which you should continue to set up any
+/// additional source files or compiler flags, and lastly call its [`compile`]
+/// method to execute the C++ build.
+///
+/// [`compile`]: https://docs.rs/cc/1.0.49/cc/struct.Build.html#method.compile
+#[must_use]
+pub fn bridge(rust_source_file: impl AsRef<Path>) -> cc::Build {
+    match try_generate_bridge(rust_source_file.as_ref()) {
+        Ok(build) => build,
+        Err(err) => {
+            let _ = writeln!(io::stderr(), "\n\ncxxbridge error: {:?}\n\n", anyhow!(err));
+            process::exit(1);
+        }
+    }
+}
+
+fn try_generate_bridge(rust_source_file: &Path) -> Result<cc::Build> {
+    let header = gen::do_generate_header(rust_source_file, Opt::default());
+    let header_path = paths::out_with_extension(rust_source_file, ".h")?;
+    fs::create_dir_all(header_path.parent().unwrap())?;
+    fs::write(&header_path, header)?;
+    paths::symlink_header(&header_path, rust_source_file);
+
+    let bridge = gen::do_generate_bridge(rust_source_file, Opt::default());
+    let bridge_path = paths::out_with_extension(rust_source_file, ".cc")?;
+    fs::write(&bridge_path, bridge)?;
+    let mut build = paths::cc_build();
+    build.file(&bridge_path);
+
+    let ref cxx_h = paths::include_dir()?.join("rust").join("cxx.h");
+    let _ = fs::create_dir_all(cxx_h.parent().unwrap());
+    let _ = fs::remove_file(cxx_h);
+    let _ = fs::write(cxx_h, gen::include::HEADER);
+
+    Ok(build)
+}

gen/build/src/syntax

@@ -0,0 +1 @@
+../../../syntax

gen/cmd/LICENSE-APACHE

@@ -0,0 +1 @@
+../../LICENSE-APACHE

gen/cmd/LICENSE-MIT

@@ -0,0 +1 @@
+../../LICENSE-MIT

gen/cmd/src/gen

@@ -0,0 +1 @@
+../../src

gen/cmd/src/syntax

@@ -0,0 +1 @@
+../../../syntax

gen/src/include

@@ -0,0 +1 @@
+../../include

macro/Cargo.toml

@@ -6,6 +6,7 @@ edition = "2018"
 license = "MIT OR Apache-2.0"
 description = "Implementation detail of the `cxx` crate."
 repository = "https://github.com/dtolnay/cxx"
+exclude = ["README.md"]
 
 [lib]
 proc-macro = true

macro/README.md

@@ -0,0 +1,3 @@
+This directory contains CXX's Rust code generator, which is a procedural macro.
+Users won't depend on this crate directly. Instead they'll invoke its macro
+through the reexport in the main `cxx` crate.