Control building from feature flag

Properly skips optional dependencies pending rust-lang/cargo#7914
More extensible for addition of new platforms

.gitignore

@@ -1,4 +1,5 @@
 /target
 **/*.rs.bk
 Cargo.lock
-.cargo/config
+.cargo/config
+glslang_actual_builder/glslang/

.gitmodules

@@ -1,3 +1,3 @@
 [submodule "glslang"]
-	path = glslang
+	path = glslang_actual_builder/glslang
 	url = https://github.com/KhronosGroup/glslang.git

Cargo.toml

@@ -5,11 +5,23 @@ authors = ["Pierre Krieger <pierre.krieger1708@gmail.com>", "The vulkano contrib
 description = "Deprecated. This crate is a temporary measure until native rust shader compilation like https://github.com/gfx-rs/naga lands."
 repository = "https://github.com/cart/glsl-to-spirv"
 license = "MIT/Apache-2.0"
-build = "build/build.rs"
 categories = ["rendering::graphics-api"]
 edition = "2018"
-links = "glslang"
 
-[build-dependencies]
-cmake = "0.1.45"
-cc = { version = "1.0.66", features = ["parallel"] }
+[target.x86_64-pc-windows-msvc.dependencies]
+glslang_actual_builder = { path = "glslang_actual_builder", default-features = false }
+
+[target.x86_64-unknown-linux-gnu.dependencies]
+glslang_actual_builder = { path = "glslang_actual_builder", default-features = false }
+
+[target.x86_64-apple-darwin.dependencies]
+glslang_actual_builder = { path = "glslang_actual_builder", default-features = false }
+
+[target.aarch64-linux-android.dependencies]
+glslang_actual_builder = { path = "glslang_actual_builder", default-features = false }
+
+[target.armv7-linux-androideabi.dependencies]
+glslang_actual_builder = { path = "glslang_actual_builder", default-features = false }
+
+[target.i686-pc-windows-msvc.dependencies]
+glslang_actual_builder = { path = "glslang_actual_builder", features = ["build-from-source"] }

glslang_actual_builder/Cargo.toml

@@ -0,0 +1,18 @@
+[package]
+name = "glslang_actual_builder"
+version = "0.1.0"
+authors = ["Pierre Krieger <pierre.krieger1708@gmail.com>", "The vulkano contributors", "Carter Anderson <mcanders1@gmail.com>", "Nicholas Rishel <rishel.nick@gmail.com>", "Martin Krisnanto Putra <grygrflzr@hotmail.com>"]
+description = "Internal builder"
+repository = "https://github.com/cart/glsl-to-spirv"
+license = "MIT/Apache-2.0"
+build = "build.rs"
+categories = ["rendering::graphics-api"]
+edition = "2018"
+
+[features]
+default = []
+build-from-source = ["cmake", "cc"]
+
+[build-dependencies]
+cmake = { version = "0.1.45", optional = true }
+cc = { version = "1.0.66", features = ["parallel"], optional = true }

glslang_actual_builder/build.rs

@@ -0,0 +1,110 @@
+use std::path::Path;
+
+fn main() {
+    let target: &str = &std::env::var("TARGET").unwrap();
+    let cargo_dir = Path::new(env!("CARGO_MANIFEST_DIR"));
+    let bin_dir = match target {
+        "x86_64-pc-windows-msvc" => cargo_dir.join("build/windows"),
+        "x86_64-unknown-linux-gnu" => cargo_dir.join("build/linux"),
+        "x86_64-apple-darwin" => cargo_dir.join("build/osx"),
+        "aarch64-linux-android" => cargo_dir.join("build/android-arm64-v8a"),
+        "armv7-linux-androideabi" => cargo_dir.join("build/android-armeabi-v7a"),
+        "i686-pc-windows-msvc" => build::build_libraries(),
+        _ => panic!("Unsupported target {}", target),
+    };
+
+    // Link order matters, make sure dependants are linked before their dependencies.
+    println!("cargo:rustc-link-search={}", bin_dir.to_str().unwrap());
+    println!("cargo:rustc-link-lib=glslang.glsltospirv");
+    println!("cargo:rustc-link-lib=HLSL.glsltospirv");
+    println!("cargo:rustc-link-lib=OGLCompiler.glsltospirv");
+    println!("cargo:rustc-link-lib=OSDependent.glsltospirv");
+    println!("cargo:rustc-link-lib=SPIRV.glsltospirv");
+    println!("cargo:rustc-link-lib=SPVRemapper.glsltospirv");
+    if target.contains("x86_64-unknown-linux-gnu") || target.contains("x86_64-apple-darwin") {
+        println!("cargo:rustc-link-lib=SPIRV-Tools-opt.glsltospirv");
+        println!("cargo:rustc-link-lib=SPIRV-Tools.glsltospirv");
+    }
+    if target.contains("android") {
+        println!("cargo:rustc-link-lib=c++_shared");
+    }
+}
+
+#[cfg(feature = "build-from-source")]
+mod build {
+    extern crate cmake;
+
+    use std::path::Path;
+    use std::path::PathBuf;
+
+    const COMMON_FILES: &[&str] = &[
+        "glslang",
+        "HLSL",
+        "OGLCompiler",
+        "OSDependent",
+        "SPIRV",
+        "SPVRemapper",
+    ];
+
+    /// Build target libraries if required,
+    /// and returns the location of library files
+    pub fn build_libraries() -> PathBuf {
+        // Prepare directories
+        let cargo_dir = Path::new(env!("CARGO_MANIFEST_DIR"));
+        let source_dir = cargo_dir.join("glslang");
+
+        let out_dir_env = std::env::var("OUT_DIR").unwrap().clone();
+        let out_dir = Path::new(&out_dir_env);
+        let install_dir = out_dir.join("install");
+        let library_dir = install_dir.join("lib");
+
+        // Re-use libraries if they exist
+        if library_dir.exists() {
+            return library_dir;
+        }
+
+        // Check glslang folder is initialized
+        let cmakelists = source_dir.join("CMakeLists.txt");
+        if !cmakelists.exists() {
+            panic!("Please make sure the glslang submodule is initialized");
+        }
+
+        // Set up "install" subdirectory
+        match std::fs::create_dir_all(&install_dir) {
+            Ok(_) => {}
+            Err(err) => panic!("Unable to create directory: {:?}", err),
+        }
+
+        // Configure and run build
+        cmake::Config::new(&source_dir)
+            .define("CMAKE_INSTALL_PREFIX", &install_dir)
+            .define("ENABLE_GLSLANG_BINARIES", "OFF")
+            .profile("Release")
+            .build_target("install")
+            .build();
+
+        // Rename library files
+        COMMON_FILES.iter().for_each(|file| {
+            match std::fs::copy(
+                library_dir.join(file).with_extension("lib"),
+                library_dir.join(file).with_extension("glsltospirv.lib"),
+            ) {
+                Ok(_) => {}
+                Err(err) => panic!("Error renaming glslang libaries: {}", err),
+            }
+        });
+
+        return library_dir;
+    }
+}
+
+#[cfg(not(feature = "build-from-source"))]
+mod build {
+    use std::path::PathBuf;
+
+    /// Build target libraries if required,
+    /// and returns the location of library files
+    pub fn build_libraries() -> PathBuf {
+        panic!("This platform must build glslang from source.");
+    }
+}