Always emit cargo dependency information (#618)

* spirv-builder: Add more control over cargo metadata printout

* lint fix

crates/spirv-builder/src/lib.rs

@@ -86,9 +86,9 @@ impl fmt::Display for SpirvBuilderError {
                 write!(f, "Crate path {} does not exist", path.display())
             }
             SpirvBuilderError::BuildFailed => f.write_str("Build failed"),
-            SpirvBuilderError::MultiModuleWithPrintMetadata => {
-                f.write_str("Multi-module build cannot be used with print_metadata = true")
-            }
+            SpirvBuilderError::MultiModuleWithPrintMetadata => f.write_str(
+                "Multi-module build cannot be used with print_metadata = MetadataPrintout::Full",
+            ),
             SpirvBuilderError::MetadataFileMissing(_) => {
                 f.write_str("Multi-module metadata file missing")
             }
@@ -107,9 +107,21 @@ pub enum MemoryModel {
     GLSL450,
 }
 
+#[derive(Debug, PartialEq, Eq)]
+pub enum MetadataPrintout {
+    /// Print no cargo metadata.
+    None,
+    /// Print only dependency information (eg for multiple modules).
+    DependencyOnly,
+    /// Print all cargo metadata.
+    ///
+    /// Includes dependency information and spirv environment variable.
+    Full,
+}
+
 pub struct SpirvBuilder {
     path_to_crate: PathBuf,
-    print_metadata: bool,
+    print_metadata: MetadataPrintout,
     release: bool,
     target: String,
     bindless: bool,
@@ -130,7 +142,7 @@ impl SpirvBuilder {
     pub fn new(path_to_crate: impl AsRef<Path>, target: impl Into<String>) -> Self {
         Self {
             path_to_crate: path_to_crate.as_ref().to_owned(),
-            print_metadata: true,
+            print_metadata: MetadataPrintout::Full,
             release: true,
             target: target.into(),
             bindless: false,
@@ -147,8 +159,8 @@ impl SpirvBuilder {
         }
     }
 
-    /// Whether to print build.rs cargo metadata (e.g. cargo:rustc-env=var=val). Defaults to true.
-    pub fn print_metadata(mut self, v: bool) -> Self {
+    /// Whether to print build.rs cargo metadata (e.g. cargo:rustc-env=var=val). Defaults to [`MetadataPrintout::Full`].
+    pub fn print_metadata(mut self, v: MetadataPrintout) -> Self {
         self.print_metadata = v;
         self
     }
@@ -230,10 +242,10 @@ impl SpirvBuilder {
         self
     }
 
-    /// Builds the module. If `print_metadata` is true, you usually don't have to inspect the path
+    /// Builds the module. If `print_metadata` is [`MetadataPrintout::Full`], you usually don't have to inspect the path
     /// in the result, as the environment variable for the path to the module will already be set.
     pub fn build(self) -> Result<CompileResult, SpirvBuilderError> {
-        if self.print_metadata && self.multimodule {
+        if (self.print_metadata == MetadataPrintout::Full) && self.multimodule {
             return Err(SpirvBuilderError::MultiModuleWithPrintMetadata);
         }
         if !self.path_to_crate.is_dir() {
@@ -248,7 +260,7 @@ impl SpirvBuilder {
             ModuleResult::SingleModule(spirv_module) => {
                 assert!(!self.multimodule);
                 let env_var = metadata_file.file_name().unwrap().to_str().unwrap();
-                if self.print_metadata {
+                if self.print_metadata == MetadataPrintout::Full {
                     println!("cargo:rustc-env={}={}", env_var, spirv_module.display());
                 }
             }
@@ -414,8 +426,9 @@ fn invoke_rustc(builder: &SpirvBuilder) -> Result<PathBuf, SpirvBuilderError> {
     let artifact = get_last_artifact(&stdout);
 
     if build.status.success() {
-        if builder.print_metadata {
-            print_deps_of(&artifact);
+        match builder.print_metadata {
+            MetadataPrintout::Full | MetadataPrintout::DependencyOnly => print_deps_of(&artifact),
+            MetadataPrintout::None => (),
         }
         Ok(artifact)
     } else {

docs/src/writing-shader-crates.md

@@ -44,7 +44,7 @@ Paste the following into the `main` for your build script.
 ```rust,no_run
 SpirvBuilder::new(path_to_shader)
         .spirv_version(1, 0)
-        .print_metadata()
+        .print_metadata(MetadataPrintout::Full)
         .build()?;
 ```
 

examples/multibuilder/src/main.rs

@@ -1,8 +1,8 @@
-use spirv_builder::SpirvBuilder;
+use spirv_builder::{MetadataPrintout, SpirvBuilder};
 
 fn main() {
     let result = SpirvBuilder::new("../shaders/sky-shader", "spirv-unknown-spv1.3")
-        .print_metadata(false)
+        .print_metadata(MetadataPrintout::DependencyOnly)
         .multimodule(true)
         .build()
         .unwrap();

examples/runners/ash/src/main.rs

@@ -68,7 +68,7 @@ use std::{
 
 use structopt::StructOpt;
 
-use spirv_builder::SpirvBuilder;
+use spirv_builder::{MetadataPrintout, SpirvBuilder};
 
 use shared::ShaderConstants;
 
@@ -174,7 +174,7 @@ pub fn compile_shaders() -> Vec<SpvFile> {
     let spv_paths: Vec<PathBuf> =
         vec![
             SpirvBuilder::new("examples/shaders/sky-shader", "spirv-unknown-vulkan1.1")
-                .print_metadata(false)
+                .print_metadata(MetadataPrintout::None)
                 .build()
                 .unwrap()
                 .module

examples/runners/wgpu/src/lib.rs

@@ -59,7 +59,7 @@ pub enum RustGPUShader {
 fn shader_module(shader: RustGPUShader) -> wgpu::ShaderModuleDescriptor<'static> {
     #[cfg(not(any(target_os = "android", target_arch = "wasm32")))]
     {
-        use spirv_builder::{Capability, SpirvBuilder};
+        use spirv_builder::{Capability, MetadataPrintout, SpirvBuilder};
         use std::borrow::Cow;
         use std::path::PathBuf;
         // Hack: spirv_builder builds into a custom directory if running under cargo, to not
@@ -81,8 +81,8 @@ fn shader_module(shader: RustGPUShader) -> wgpu::ShaderModuleDescriptor<'static>
             .iter()
             .copied()
             .collect::<PathBuf>();
-        let mut builder =
-            SpirvBuilder::new(crate_path, "spirv-unknown-vulkan1.1").print_metadata(false);
+        let mut builder = SpirvBuilder::new(crate_path, "spirv-unknown-vulkan1.1")
+            .print_metadata(MetadataPrintout::None);
         for &cap in capabilities {
             builder = builder.capability(cap);
         }