Merge #670

670: Implement `Cross.toml` deserialization using `serde` r=Emilgardis a=mntns

This PR implements the deserialization of the `Cross.toml` config using `serde`. It can therefore be seen as some preliminary work on the issues #657, #664, and is related to #532 on #624.

I added some basic documentation as module-level documentation, although I'm not sure whether this is the best place for that. Ideally it should be documentated in the `README.md` at some point. Furthermore, `CrossToml` lives in its own module, but a more suitable place might be the `config` module.

Co-authored-by: Niklas Kunz <[email protected]>

CHANGELOG.md

@@ -5,6 +5,7 @@ This project adheres to [Semantic Versioning](http://semver.org/).
 
 ## [Unreleased]
 
+- #670 - Use serde for deserialization of Cross.toml
 - Change rust edition to 2021 and bump MSRV for the cross binary to 1.58.1
 - #654 - Use color-eyre for error reporting
 - #658 - Upgrade dependencies

Cargo.toml

@@ -19,6 +19,7 @@ rustc_version = "0.4"
 toml = "0.5"
 which = { version = "4", default_features = false }
 shell-escape = "0.1"
+serde = { version = "1", features = ["derive"] }
 serde_json = "1"
 
 [target.'cfg(not(windows))'.dependencies]

README.md

@@ -83,7 +83,8 @@ $ cross rustc --target powerpc-unknown-linux-gnu --release -- -C lto
 ## Configuration
 
 You can place a `Cross.toml` file in the root of your Cargo project or use a
-`CROSS_CONFIG` environment variable to tweak `cross`'s behavior:
+`CROSS_CONFIG` environment variable to tweak `cross`'s behavior. The format
+of `Cross.toml` is documented in [docs/cross_toml.md](docs/cross_toml.md).
 
 ### Custom Docker images
 

docs/cross_toml.md

@@ -0,0 +1,32 @@
+The `cross` configuration in the `Cross.toml` file, can contain the following elements:
+
+# `build`
+The `build` key allows you to set global variables, e.g.:
+
+```toml
+[build]
+xargo = true
+```
+
+# `build.env`
+With the `build.env` key you can globally set volumes that should be mounted
+in the Docker container or environment variables that should be passed through.
+For example:
+
+```toml
+[build.env]
+volumes = ["VOL1_ARG", "VOL2_ARG"]
+passthrough = ["IMPORTANT_ENV_VARIABLES"]
+```
+
+# `target.TARGET`
+The `target` key allows you to specify parameters for specific compilation targets.
+
+```toml
+[target.aarch64-unknown-linux-gnu]
+volumes = ["VOL1_ARG", "VOL2_ARG"]
+passthrough = ["VAR1", "VAR2"]
+xargo = false
+image = "test-image"
+runner = "custom-runner"
+```

src/config.rs

@@ -1,4 +1,4 @@
-use crate::{Result, Target, Toml};
+use crate::{CrossToml, Result, Target};
 
 use crate::errors::*;
 use std::collections::HashMap;
@@ -101,27 +101,27 @@ fn split_to_cloned_by_ws(string: &str) -> Vec<String> {
 
 #[derive(Debug)]
 pub struct Config {
-    toml: Option<Toml>,
+    toml: Option<CrossToml>,
     env: Environment,
 }
 
 impl Config {
-    pub fn new(toml: Option<Toml>) -> Self {
+    pub fn new(toml: Option<CrossToml>) -> Self {
         Config {
             toml,
             env: Environment::new(None),
         }
     }
 
     #[cfg(test)]
-    fn new_with(toml: Option<Toml>, env: Environment) -> Self {
+    fn new_with(toml: Option<CrossToml>, env: Environment) -> Self {
         Config { toml, env }
     }
 
     pub fn xargo(&self, target: &Target) -> Result<Option<bool>> {
         let (build_xargo, target_xargo) = self.env.xargo(target)?;
         let (toml_build_xargo, toml_target_xargo) = if let Some(ref toml) = self.toml {
-            toml.xargo(target)?
+            toml.xargo(target)
         } else {
             (None, None)
         };
@@ -145,15 +145,17 @@ impl Config {
         if let Some(env_value) = env_value {
             return Ok(Some(env_value));
         }
-        self.toml.as_ref().map_or(Ok(None), |t| t.image(target))
+        self.toml.as_ref().map_or(Ok(None), |t| Ok(t.image(target)))
     }
 
     pub fn runner(&self, target: &Target) -> Result<Option<String>> {
         let env_value = self.env.runner(target);
         if let Some(env_value) = env_value {
             return Ok(Some(env_value));
         }
-        self.toml.as_ref().map_or(Ok(None), |t| t.runner(target))
+        self.toml
+            .as_ref()
+            .map_or(Ok(None), |t| Ok(t.runner(target)))
     }
 
     pub fn env_passthrough(&self, target: &Target) -> Result<Vec<String>> {
@@ -179,15 +181,15 @@ impl Config {
         Ok(collected)
     }
 
-    fn sum_of_env_toml_values<'a>(
-        toml_getter: impl FnOnce() -> Option<Result<Vec<&'a str>>>,
+    fn sum_of_env_toml_values(
+        toml_getter: impl FnOnce() -> Option<Vec<String>>,
         env_values: Option<Vec<String>>,
     ) -> Result<Vec<String>> {
         let mut collect = vec![];
         if let Some(mut vars) = env_values {
             collect.append(&mut vars);
         } else if let Some(toml_values) = toml_getter() {
-            collect.extend(toml_values?.into_iter().map(|v| v.to_string()));
+            collect.extend(toml_values.into_iter());
         }
 
         Ok(collect)
@@ -277,13 +279,8 @@ mod tests {
         use super::*;
         use std::matches;
 
-        fn toml(content: &str) -> Result<crate::Toml> {
-            Ok(crate::Toml {
-                table: match content.parse().wrap_err("couldn't parse toml")? {
-                    toml::Value::Table(table) => table,
-                    _ => eyre::bail!("couldn't parse toml as TOML table"),
-                },
-            })
+        fn toml(content: &str) -> Result<crate::CrossToml> {
+            Ok(CrossToml::from_str(content).wrap_err("couldn't parse toml")?)
         }
 
         #[test]