SHADERC_STATIC="./here/"

README.md

@@ -16,14 +16,7 @@ code that happens to be owned by Google.
 Usage
 -----
 
-This library uses [`build.rs`](build/build.rs) to automatically check out
-and compile a copy of native C++ shaderc and link to the generated artifacts,
-which requires `git`, `cmake`, and `python` existing in the `PATH`.
-
-To turn off this feature, specify `--no-default-features` when building.
-But then you will need to place a copy of the `shaderc_combined` static library
-to the location (printed out in the warning message) that is scanned by the
-linker.
+The included shaderc-sys crate uses [`build.rs`](shaderc-sys/build/build.rs) to discover or build a copy of libshaderc. See Setup section.
 
 First add to your `Cargo.toml`:
 
@@ -80,7 +73,19 @@ assert!(text_result.as_text().starts_with("; SPIR-V\n"));
 Setup
 -----
 
-To build the shaderc-rs crate, the following tools must be installed and available on `PATH`:
+Building the underlying libshaderc from source takes a while. You can provide it or use system libraries by setting the `SHADERC_STATIC` path. On Linux, the build script also checks for independent libglslang and libSPIRV and includes them only if found.
+
+`--no-default-features` still works on shaderc-rs, but shaderc-sys implements this behavior in a deprecated manner. Prefer `SHADERC_STATIC="../path/to/libshaderc/and/glsang/etc/"`. This method only works with a monolithic **libshaderc_combined.a**.
+
+If you need to prefer building libshaderc from source to override system libraries etc, explicitly enable the build-from-source feature:
+```
+cargo build --features=build-from-source
+```
+
+The shaderc-sys [`build.rs`](shaderc-sys/build/build.rs) will automatically check out and compile a copy of native C++ shaderc and link to the generated artifacts,
+which requires `git`, `cmake`, and `python` existing in the `PATH`.
+
+To build your own libshaderc for the shaderc-sys crate, the following tools must be installed and available on `PATH`:
 - [CMake](https://cmake.org/)
 - [Git](https://git-scm.com/)
 - [Python](https://www.python.org/) (works with both Python 2.x and 3.x, on windows the executable must be named `python.exe`)
@@ -132,6 +137,8 @@ For example on ubuntu:
 sudo apt-get install build-essential git python cmake
 ```
 
+On Arch linux, the [shaderc package](https://www.archlinux.org/packages/extra/x86_64/shaderc/) will include glsang and SPIRV libs in a detectable location.
+
 ### macOS Example Setup
 
 Assuming Homebrew:

shaderc-sys/Cargo.toml

@@ -17,6 +17,7 @@ name = "shaderc_sys"
 [features]
 check-passthrough = []
 dont-use-deprecated = []
+build-from-source = []
 
 [dependencies]
 libc = "0.2"

shaderc-sys/build/build.rs

@@ -15,8 +15,13 @@
 mod cmd_finder;
 
 use std::env;
+use std::env::consts;
 use std::path::{Path, PathBuf};
 
+static COMBINED_LIB: &str = "shaderc_combined";
+static COMBINED_LIB_FILE: &str = "libshaderc_combined.a";
+static SPIRV_LIB: &str = "libSPIRV.a";
+
 fn build_shaderc(shaderc_dir: &PathBuf, use_ninja: bool) -> PathBuf {
  let mut config = cmake::Config::new(shaderc_dir);
  config
@@ -55,6 +60,7 @@ fn build_shaderc_msvc(shaderc_dir: &PathBuf, use_ninja: bool) -> PathBuf {
 }
 
 fn main() {
+ // Deprecated --no-defaults path inhereted from before shaderc-rs & shaderc-sys split
  if env::var("CARGO_FEATURE_CHECK_PASSTHROUGH").is_ok()
  && env::var("CARGO_FEATURE_DONT_USE_DEPRECATED").is_err()
  {
@@ -67,9 +73,93 @@ fn main() {
  );
  println!("cargo:rustc-link-search=native={}", out_dir);
  println!("cargo:rustc-link-lib=static=shaderc_combined");
+ emit_stdc_link();
  return;
  }
 
+ // Explicit overrides first
+ let mut search_dir = if let Ok(lib_dir) = env::var("SHADERC_LIB_DIR") {
+ println!("cargo:warning=Using specified pre-built libshaderc");
+ Some(lib_dir)
+ } else if let Ok(lib_path) = env::var("SHADERC_LIB_PATH") {
+ println!("cargo:warning=Using specified pre-built libshaderc");
+ Some(lib_path)
+ } else if let Ok(lib_path) = env::var("SHADERC_STATIC") {
+ println!("cargo:warning=Using specified pre-built libshaderc");
+ Some(lib_path)
+ } else {
+ None
+ };
+
+ let target_os = env::var("CARGO_CFG_TARGET_OS").unwrap();
+ let target_env = env::var("CARGO_CFG_TARGET_ENV").unwrap();
+
+ // Guess linux path for system library unless requested to do source build
+ if search_dir.is_none()
+ && target_os == "linux"
+ && env::var("CARGO_FEATURE_BUILD_FROM_SOURCE").is_err()
+ {
+ println!("cargo:warning=Checking for system installed libraries");
+ search_dir = Some("/usr/lib/".to_owned());
+ }
+
+ // Try to build with the static lib if a path was received or chosen
+ if let Some(search_dir) = search_dir {
+ let search_path = Path::new(&search_dir);
+ let combined_lib_path = search_path.join(COMBINED_LIB_FILE);
+ let dylib_name = format!("{}shaderc{}", consts::DLL_PREFIX, consts::DLL_SUFFIX);
+ let dylib_path = search_path.join(dylib_name.clone());
+
+ if let Some((lib_dir, lib_name)) = {
+ if combined_lib_path.exists() {
+ Some((search_dir.clone(), COMBINED_LIB.to_owned()))
+ } else if dylib_path.exists() {
+ Some((search_dir.clone(), dylib_name))
+ } else {
+ None
+ }
+ } {
+ match (target_os.as_str(), target_env.as_str()) {
+ ("linux", _) => {
+ println!("cargo:rustc-link-search=native={}", lib_dir);
+ let spirv_path = search_path.join(SPIRV_LIB);
+ if spirv_path.exists() {
+ println!("cargo:warning=Found SPIRV. Linking SPIRV & glslang");
+ println!("cargo:rustc-link-lib=static=SPIRV");
+ println!("cargo:rustc-link-lib=static=SPIRV-Tools-opt");
+ println!("cargo:rustc-link-lib=static=SPIRV-Tools");
+ println!("cargo:rustc-link-lib=static=glslang");
+ } else {
+ println!("cargo:warning=Only libshaderc library found. Assuming SPIRV & glslang included.");
+ }
+ println!("cargo:rustc-link-lib=static={}", lib_name);
+ println!("cargo:rustc-link-lib=dylib=stdc++");
+ return;
+ }
+ ("windows", "gnu") => {
+ println!("cargo:warning=Windows MinGW static builds experimental");
+ println!("cargo:rustc-link-search=native={}", lib_dir);
+ println!("cargo:rustc-link-lib=static={}", lib_name);
+ println!("cargo:rustc-link-lib=dylib=stdc++");
+ return;
+ }
+ ("macos", _) => {
+ println!("cargo:warning=MacOS static builds experimental");
+ println!("cargo:rustc-link-search=native={}", lib_dir);
+ println!("cargo:rustc-link-lib=static={}", lib_name);
+ println!("cargo:rustc-link-lib=dylib=c++");
+ return;
+ }
+ (_, _) => {
+ println!("cargo:warning=Platform unsupported for pre-built libshaderc");
+ }
+ }
+ } else {
+ println!("cargo:warning=pre-built library not found");
+ }
+ }
+
+ println!("cargo:warning=Falling back to from-source build");
  let mut finder = cmd_finder::CommandFinder::new();
 
  finder.must_have("cmake");
@@ -78,9 +168,6 @@ fn main() {
 
  let has_ninja = finder.maybe_have("ninja").is_some();
 
- let target_os = env::var("CARGO_CFG_TARGET_OS").unwrap();
- let target_env = env::var("CARGO_CFG_TARGET_ENV").unwrap();
-
  let manifest_dir = env::var("CARGO_MANIFEST_DIR").unwrap();
  let shaderc_dir = Path::new(&manifest_dir).join("build");
 
@@ -91,10 +178,16 @@ fn main() {
  };
 
  lib_path.push("lib");
-
  println!("cargo:rustc-link-search=native={}", lib_path.display());
  println!("cargo:rustc-link-lib=static=shaderc_combined");
 
+ emit_stdc_link();
+}
+
+fn emit_stdc_link() {
+ let target_os = env::var("CARGO_CFG_TARGET_OS").unwrap();
+ let target_env = env::var("CARGO_CFG_TARGET_ENV").unwrap();
+
  match (target_os.as_str(), target_env.as_str()) {
  ("linux", _) | ("windows", "gnu") => println!("cargo:rustc-link-lib=dylib=stdc++"),
  ("macos", _) => println!("cargo:rustc-link-lib=dylib=c++"),