[nextest-runner] fix order of cli config and env parsing

See inline comments for more.

nextest-runner/src/cargo_config/discovery.rs

@@ -77,9 +77,14 @@ impl CargoConfigs {
     pub(crate) fn discovered_configs(
         &self,
     ) -> impl Iterator<Item = DiscoveredConfig<'_>> + DoubleEndedIterator + '_ {
-        // TODO/NOTE: https://github.com/rust-lang/cargo/issues/10992 means that currently
-        // environment variables are privileged over files passed in over the CLI. Once this
-        // behavior is fixed in upstream cargo, it should also be fixed here.
+        // NOTE: The order is:
+        // 1. --config k=v
+        // 2. --config <file>
+        // 3. Environment variables
+        // 4. .cargo/configs.
+        //
+        // 2 and 3 used to be reversed in older versions of Rust, but this has been fixed as of Rust
+        // 1.68 (https://github.com/rust-lang/cargo/pull/11077).
         let cli_option_iter = self.cli_configs.iter().filter_map(|(source, config)| {
             matches!(source, CargoConfigSource::CliOption)
                 .then(|| DiscoveredConfig::CliOption { config, source })
@@ -96,8 +101,8 @@ impl CargoConfigs {
             .map(|(source, config)| DiscoveredConfig::File { config, source });
 
         cli_option_iter
-            .chain(std::iter::once(DiscoveredConfig::Env))
             .chain(cli_file_iter)
+            .chain(std::iter::once(DiscoveredConfig::Env))
             .chain(cargo_config_file_iter)
     }
 }

nextest-runner/src/cargo_config/target_triple.rs

@@ -301,8 +301,10 @@ mod tests {
             })
         );
 
-        // --config <path> should be parsed correctly. Config files currently come after
-        // keys and values passed in via --config, and after the environment.
+        // --config <path> should be parsed correctly. Config files passed in via --config currently
+        // come after keys and values passed in via --config, and before the environment (this
+        // didn't used to be the case in older versions of Rust, but is now the case as of Rust 1.68
+        // with https://github.com/rust-lang/cargo/pull/11077).
         assert_eq!(
             find_target_triple(&["extra-config.toml"], None, &dir_foo_path, &dir_path),
             Some(TargetTriple {
@@ -320,8 +322,10 @@ mod tests {
                 &dir_path
             ),
             Some(TargetTriple {
-                platform: platform("aarch64-pc-windows-msvc"),
-                source: TargetTripleSource::Env,
+                platform: platform("aarch64-unknown-linux-gnu"),
+                source: TargetTripleSource::CargoConfig {
+                    source: CargoConfigSource::File(dir_foo_path.join("extra-config.toml")),
+                },
             })
         );
         assert_eq!(