feat: display valid values in --crate-type

Author: malezjaa

compiler/rustc_session/src/config.rs

@@ -13,7 +13,6 @@ use std::path::{Path, PathBuf};
 use std::str::{self, FromStr};
 use std::sync::LazyLock;
 use std::{cmp, fmt, fs, iter};
-
 use rustc_data_structures::fx::{FxHashSet, FxIndexMap};
 use rustc_data_structures::stable_hasher::{StableOrd, ToStableHashKey};
 use rustc_errors::emitter::HumanReadableErrorType;
@@ -1296,6 +1295,29 @@ impl CrateType {
             CrateType::Executable | CrateType::Cdylib | CrateType::Staticlib => false,
         }
     }
+
+    pub fn shorthand(&self) -> &'static str {
+        match *self {
+            CrateType::Executable => "bin",
+            CrateType::Dylib => "dylib",
+            CrateType::Rlib => "rlib",
+            CrateType::Staticlib => "lib",
+            CrateType::Cdylib => "cdylib",
+            CrateType::ProcMacro => "proc-macro",
+        }
+    }
+
+    fn shorthands_display() -> String {
+        format!(
+            "`{}`, `{}`, `{}`, `{}`, `{}`, `{}`",
+            CrateType::Executable.shorthand(),
+            CrateType::Dylib.shorthand(),
+            CrateType::Rlib.shorthand(),
+            CrateType::Staticlib.shorthand(),
+            CrateType::Cdylib.shorthand(),
+            CrateType::ProcMacro.shorthand(),
+        )
+    }
 }
 
 #[derive(Clone, Hash, Debug, PartialEq, Eq)]
@@ -2678,7 +2700,7 @@ pub fn parse_crate_types_from_list(list_list: Vec<String>) -> Result<Vec<CrateTy
                 "cdylib" => CrateType::Cdylib,
                 "bin" => CrateType::Executable,
                 "proc-macro" => CrateType::ProcMacro,
-                _ => return Err(format!("unknown crate type: `{part}`")),
+                _ => return Err(format!("unknown crate type: `{part}` - expected one of: {display}", display = CrateType::shorthands_display())),
             };
             if !crate_types.contains(&new_part) {
                 crate_types.push(new_part)