Refactor host and target config table loads to deduplicate logic.

src/cargo/util/config/target.rs

@@ -66,45 +66,31 @@ pub(super) fn load_target_cfgs(config: &Config) -> CargoResult<Vec<(String, Targ
 
 /// Loads a single `[host]` table for the given triple.
 pub(super) fn load_host_triple(config: &Config, triple: &str) -> CargoResult<TargetConfig> {
-    // This needs to get each field individually because it cannot fetch the
-    // struct all at once due to `links_overrides`. Can't use `serde(flatten)`
-    // because it causes serde to use `deserialize_map` which means the config
-    // deserializer does not know which keys to deserialize, which means
-    // environment variables would not work.
     let host_triple_key = ConfigKey::from_str(&format!("host.{}", triple));
     let host_prefix = match config.get_cv(&host_triple_key)? {
         Some(_) => format!("host.{}", triple),
         None => "host".to_string(),
     };
-    let runner: OptValue<PathAndArgs> = config.get(&format!("{}.runner", host_prefix))?;
-    let rustflags: OptValue<StringList> = config.get(&format!("{}.rustflags", host_prefix))?;
-    let linker: OptValue<ConfigRelativePath> = config.get(&format!("{}.linker", host_prefix))?;
-    // Links do not support environment variables.
-    let target_key = ConfigKey::from_str(&host_prefix);
-    let links_overrides = match config.get_table(&target_key)? {
-        Some(links) => parse_links_overrides(&target_key, links.val, config)?,
-        None => BTreeMap::new(),
-    };
-    Ok(TargetConfig {
-        runner,
-        rustflags,
-        linker,
-        links_overrides,
-    })
+    load_config_table(config, &host_prefix)
 }
 
 /// Loads a single `[target]` table for the given triple.
 pub(super) fn load_target_triple(config: &Config, triple: &str) -> CargoResult<TargetConfig> {
+    load_config_table(config, &format!("target.{}", triple))
+}
+
+/// Loads a single table for the given prefix.
+fn load_config_table(config: &Config, prefix: &str) -> CargoResult<TargetConfig> {
     // This needs to get each field individually because it cannot fetch the
     // struct all at once due to `links_overrides`. Can't use `serde(flatten)`
     // because it causes serde to use `deserialize_map` which means the config
     // deserializer does not know which keys to deserialize, which means
     // environment variables would not work.
-    let runner: OptValue<PathAndArgs> = config.get(&format!("target.{}.runner", triple))?;
-    let rustflags: OptValue<StringList> = config.get(&format!("target.{}.rustflags", triple))?;
-    let linker: OptValue<ConfigRelativePath> = config.get(&format!("target.{}.linker", triple))?;
+    let runner: OptValue<PathAndArgs> = config.get(&format!("{}.runner", prefix))?;
+    let rustflags: OptValue<StringList> = config.get(&format!("{}.rustflags", prefix))?;
+    let linker: OptValue<ConfigRelativePath> = config.get(&format!("{}.linker", prefix))?;
     // Links do not support environment variables.
-    let target_key = ConfigKey::from_str(&format!("target.{}", triple));
+    let target_key = ConfigKey::from_str(prefix);
     let links_overrides = match config.get_table(&target_key)? {
         Some(links) => parse_links_overrides(&target_key, links.val, config)?,
         None => BTreeMap::new(),