infer linker flavor by linker name if it's sufficiently specific

Author: usamoi

compiler/rustc_target/src/spec/mod.rs

@@ -303,15 +303,16 @@ impl LinkerFlavor {
         }
     }
 
-    fn infer_linker_hints(linker_stem: &str) -> (Option<Cc>, Option<Lld>) {
+    fn infer_linker_hints(linker_stem: &str) -> Result<Self, (Option<Cc>, Option<Lld>)> {
         // Remove any version postfix.
         let stem = linker_stem
             .rsplit_once('-')
             .and_then(|(lhs, rhs)| rhs.chars().all(char::is_numeric).then_some(lhs))
             .unwrap_or(linker_stem);
 
-        // GCC/Clang can have an optional target prefix.
-        if stem == "emcc"
+        if stem == "llvm-bitcode-linker" {
+            Ok(Self::Llbc)
+        } else if stem == "emcc" // GCC/Clang can have an optional target prefix.
             || stem == "gcc"
             || stem.ends_with("-gcc")
             || stem == "g++"
@@ -321,19 +322,19 @@ impl LinkerFlavor {
             || stem == "clang++"
             || stem.ends_with("-clang++")
         {
-            (Some(Cc::Yes), Some(Lld::No))
+            Err((Some(Cc::Yes), Some(Lld::No)))
         } else if stem == "wasm-ld"
             || stem.ends_with("-wasm-ld")
             || stem == "ld.lld"
             || stem == "lld"
             || stem == "rust-lld"
             || stem == "lld-link"
         {
-            (Some(Cc::No), Some(Lld::Yes))
+            Err((Some(Cc::No), Some(Lld::Yes)))
         } else if stem == "ld" || stem.ends_with("-ld") || stem == "link" {
-            (Some(Cc::No), Some(Lld::No))
+            Err((Some(Cc::No), Some(Lld::No)))
         } else {
-            (None, None)
+            Err((None, None))
         }
     }
 
@@ -357,7 +358,10 @@ impl LinkerFlavor {
     }
 
     pub fn with_linker_hints(self, linker_stem: &str) -> LinkerFlavor {
-        self.with_hints(LinkerFlavor::infer_linker_hints(linker_stem))
+        match LinkerFlavor::infer_linker_hints(linker_stem) {
+            Ok(linker_flavor) => linker_flavor,
+            Err(hints) => self.with_hints(hints),
+        }
     }
 
     pub fn check_compatibility(self, cli: LinkerFlavorCli) -> Option<String> {