Throw error if CARGO_TARGET_DIR is an empty string

src/cargo/util/config/mod.rs

@@ -450,10 +450,24 @@ impl Config {
  if let Some(dir) = &self.target_dir {
  Ok(Some(dir.clone()))
  } else if let Some(dir) = env::var_os("CARGO_TARGET_DIR") {
+ // Check if the CARGO_TARGET_DIR environment variable is set to an empty string.
+ if dir.to_string_lossy() == "" {
+ anyhow::bail!("the target directory is set to an empty string in the `CARGO_TARGET_DIR` environment variable")
+ }
+
  Ok(Some(Filesystem::new(self.cwd.join(dir))))
  } else if let Some(val) = &self.build_config()?.target_dir {
- let val = val.resolve_path(self);
- Ok(Some(Filesystem::new(val)))
+ let path = val.resolve_path(self);
+
+ // Check if the target directory is set to an empty string in the config.toml file.
+ if val.raw_value() == "" {
+ anyhow::bail!(format!(
+ "the target directory is set to an empty string in {}",
+ val.value().definition
+ ),)
+ }
+
+ Ok(Some(Filesystem::new(path)))
  } else {
  Ok(None)
  }

src/cargo/util/config/path.rs

@@ -10,6 +10,11 @@ use std::path::PathBuf;
 pub struct ConfigRelativePath(Value<String>);
 
 impl ConfigRelativePath {
+ /// Returns the underlying value.
+ pub fn value(&self) -> &Value<String> {
+ &self.0
+ }
+
  /// Returns the raw underlying configuration value for this key.
  pub fn raw_value(&self) -> &str {
  &self.0.val

tests/testsuite/config.rs

@@ -1483,3 +1483,31 @@ Caused by:
  unknown variant `invalid`, expected one of `debuginfo`, `none`, `symbols`",
  );
 }
+
+#[cargo_test]
+fn cargo_target_empty_cfg() {
+ write_config(
+ "\
+[build]
+target-dir = ''
+",
+ );
+
+ let config = new_config();
+
+ assert_error(
+ config.target_dir().unwrap_err(),
+ "the target directory is set to an empty string in [..]/.cargo/config",
+ );
+}
+
+#[cargo_test]
+fn cargo_target_empty_env() {
+ let project = project().build();
+
+ project.cargo("build")
+ .env("CARGO_TARGET_DIR", "")
+ .with_stderr("error: the target directory is set to an empty string in the `CARGO_TARGET_DIR` environment variable")
+ .with_status(101)
+ .run()
+}