Add global option --absolute-paths

src/bin/cargo/cli.rs

@@ -333,6 +333,7 @@ fn config_configure(
     let frozen = args.flag("frozen") || global_args.frozen;
     let locked = args.flag("locked") || global_args.locked;
     let offline = args.flag("offline") || global_args.offline;
+    let absolute_paths = args.flag("absolute-paths") || global_args.offline;
     let mut unstable_flags = global_args.unstable_flags;
     if let Some(values) = args.get_many::<String>("unstable-features") {
         unstable_flags.extend(values.cloned());
@@ -351,6 +352,7 @@ fn config_configure(
         arg_target_dir,
         &unstable_flags,
         &config_args,
+        absolute_paths,
     )?;
     Ok(())
 }
@@ -470,6 +472,7 @@ See 'cargo help <command>' for more information on a specific command.\n",
         .arg(flag("frozen", "Require Cargo.lock and cache are up to date").global(true))
         .arg(flag("locked", "Require Cargo.lock is up to date").global(true))
         .arg(flag("offline", "Run without accessing the network").global(true))
+        .arg(flag("absolute-paths", "Use absolute paths when calling rust").global(true))
         .arg(multi_opt("config", "KEY=VALUE", "Override a configuration value").global(true))
         .arg(
             Arg::new("unstable-features")

src/cargo/util/config/mod.rs

@@ -200,6 +200,8 @@ pub struct Config {
     doc_extern_map: LazyCell<RustdocExternMap>,
     progress_config: ProgressConfig,
     env_config: LazyCell<EnvConfig>,
+    /// Use absolute paths when invoking rustc
+    absolute_paths: bool,
     /// This should be false if:
     /// - this is an artifact of the rustc distribution process for "stable" or for "beta"
     /// - this is an `#[test]` that does not opt in with `enable_nightly_features`
@@ -274,6 +276,7 @@ impl Config {
             frozen: false,
             locked: false,
             offline: false,
+            absolute_paths: false,
             jobserver: unsafe {
                 if GLOBAL_JOBSERVER.is_null() {
                     None
@@ -896,6 +899,7 @@ impl Config {
         target_dir: &Option<PathBuf>,
         unstable_flags: &[String],
         cli_config: &[String],
+        absolute_paths: bool,
     ) -> CargoResult<()> {
         for warning in self
             .unstable_flags
@@ -961,6 +965,7 @@ impl Config {
                 .and_then(|n| n.offline)
                 .unwrap_or(false);
         self.target_dir = cli_target_dir;
+        self.absolute_paths = absolute_paths;
 
         self.load_unstable_flags_from_config()?;
 
@@ -1014,6 +1019,10 @@ impl Config {
         !self.frozen && !self.locked
     }
 
+    pub fn absolute_paths(&self) -> bool {
+        self.absolute_paths
+    }
+
     /// Loads configuration from the filesystem.
     pub fn load_values(&self) -> CargoResult<HashMap<String, ConfigValue>> {
         self.load_values_from(&self.cwd)

src/cargo/util/workspace.rs

@@ -116,8 +116,12 @@ pub fn path_args(ws: &Workspace<'_>, unit: &Unit) -> (PathBuf, PathBuf) {
     };
     assert!(src.is_absolute());
     if unit.pkg.package_id().source_id().is_path() {
-        if let Ok(path) = src.strip_prefix(ws_root) {
-            return (path.to_path_buf(), ws_root.to_path_buf());
+        if ws.config().absolute_paths() {
+            return (src, ws_root.to_path_buf());
+        } else {
+            if let Ok(path) = src.strip_prefix(ws_root) {
+                return (path.to_path_buf(), ws_root.to_path_buf());
+            }
         }
     }
     (src, unit.pkg.root().to_path_buf())

tests/testsuite/config.rs

@@ -90,6 +90,7 @@ impl ConfigBuilder {
             &None,
             &self.unstable,
             &self.config_args,
+            false,
         )?;
         Ok(config)
     }

tests/testsuite/paths.rs

@@ -224,3 +224,26 @@ dependencies; the dependency on `baz` was either added or\
         )
         .run();
 }
+
+#[cargo_test]
+fn absolute_path_tests() {
+    let foo = project()
+        .file(
+            "Cargo.toml",
+            r#"
+                [package]
+                name = "foo"
+                version = "0.0.1"
+                authors = []
+            "#,
+        )
+        .file("src/main.rs", "fn main() { failure }")
+        .build();
+
+    println!("{}", foo.root().to_str().unwrap());
+    foo.cargo("--absolute-paths build")
+        .with_stderr_contains("[..]--> [ROOT]/foo/src/main.rs:1:13[..]")
+        .with_stderr_contains("[COMPILING] foo v0.0.1 ([ROOT]/foo)")
+        .with_status(101)
+        .run();
+}