build(rust): vendor googletest crate

third_party/crates/autocfg-1.5.1/src/rustc.rs

@@ -0,0 +1,89 @@
+use std::env;
+use std::ffi::OsString;
+use std::path::PathBuf;
+use std::process::Command;
+
+use super::error::Error;
+use super::version::Version;
+
+#[derive(Clone, Debug)]
+pub struct Rustc {
+    rustc: PathBuf,
+    rustc_wrapper: Option<PathBuf>,
+    rustc_workspace_wrapper: Option<PathBuf>,
+}
+
+impl Rustc {
+    pub fn new() -> Self {
+        Rustc {
+            rustc: env::var_os("RUSTC")
+                .unwrap_or_else(|| "rustc".into())
+                .into(),
+            rustc_wrapper: get_rustc_wrapper(false),
+            rustc_workspace_wrapper: get_rustc_wrapper(true),
+        }
+    }
+
+    /// Build the command with possible wrappers.
+    pub fn command(&self) -> Command {
+        let mut rustc = self
+            .rustc_wrapper
+            .iter()
+            .chain(self.rustc_workspace_wrapper.iter())
+            .chain(Some(&self.rustc));
+        let mut command = Command::new(rustc.next().unwrap());
+        for arg in rustc {
+            command.arg(arg);
+        }
+        command
+    }
+
+    /// Try to get the `rustc` version.
+    pub fn version(&self) -> Result<Version, Error> {
+        // Some wrappers like clippy-driver don't pass through version commands,
+        // so we try to fall back to combinations without each wrapper.
+        macro_rules! try_version {
+            ($command:expr) => {
+                if let Ok(value) = Version::from_command($command) {
+                    return Ok(value);
+                }
+            };
+        }
+
+        let rustc = &self.rustc;
+        if let Some(ref rw) = self.rustc_wrapper {
+            if let Some(ref rww) = self.rustc_workspace_wrapper {
+                try_version!(Command::new(rw).args(&[rww, rustc]));
+            }
+            try_version!(Command::new(rw).arg(rustc));
+        }
+        if let Some(ref rww) = self.rustc_workspace_wrapper {
+            try_version!(Command::new(rww).arg(rustc));
+        }
+        Version::from_command(&mut Command::new(rustc))
+    }
+}
+
+fn get_rustc_wrapper(workspace: bool) -> Option<PathBuf> {
+    // We didn't really know whether the workspace wrapper is applicable until Cargo started
+    // deliberately setting or unsetting it in rust-lang/cargo#9601. We'll use the encoded
+    // rustflags as a proxy for that change for now, but we could instead check version 1.55.
+    if workspace && env::var_os("CARGO_ENCODED_RUSTFLAGS").is_none() {
+        return None;
+    }
+
+    let name = if workspace {
+        "RUSTC_WORKSPACE_WRAPPER"
+    } else {
+        "RUSTC_WRAPPER"
+    };
+
+    if let Some(wrapper) = env::var_os(name) {
+        // NB: `OsStr` didn't get `len` or `is_empty` until 1.9.
+        if wrapper != OsString::new() {
+            return Some(wrapper.into());
+        }
+    }
+
+    None
+}