Allow LTO for dylibs

1 files changed, 4 insertions, 13 deletions

diff --git a/compiler/rustc_codegen_llvm/src/back/lto.rs b/compiler/rustc_codegen_llvm/src/back/lto.rs
index cef7bf1e803..fb58d5f7df2 100644
--- a/compiler/rustc_codegen_llvm/src/back/lto.rs
+++ b/compiler/rustc_codegen_llvm/src/back/lto.rs
@@ -32,8 +32,8 @@ pub const THIN_LTO_KEYS_INCR_COMP_FILE_NAME: &str = "thin-lto-past-keys.bin";
 
 pub fn crate_type_allows_lto(crate_type: CrateType) -> bool {
     match crate_type {
-        CrateType::Executable | CrateType::Staticlib | CrateType::Cdylib => true,
-        CrateType::Dylib | CrateType::Rlib | CrateType::ProcMacro => false,
+        CrateType::Executable | CrateType::Dylib | CrateType::Staticlib | CrateType::Cdylib => true,
+        CrateType::Rlib | CrateType::ProcMacro => false,
     }
 }
 
@@ -73,17 +73,6 @@ fn prepare_lto(
     // with either fat or thin LTO
     let mut upstream_modules = Vec::new();
     if cgcx.lto != Lto::ThinLocal {
-        if cgcx.opts.cg.prefer_dynamic {
-            diag_handler
-                .struct_err("cannot prefer dynamic linking when performing LTO")
-                .note(
-                    "only 'staticlib', 'bin', and 'cdylib' outputs are \
-                               supported with LTO",
-                )
-                .emit();
-            return Err(FatalError);
-        }
-
         // Make sure we actually can run LTO
         for crate_type in cgcx.crate_types.iter() {
             if !crate_type_allows_lto(*crate_type) {
@@ -92,6 +81,8 @@ fn prepare_lto(
                                             static library outputs",
                 );
                 return Err(e);
+            } else if *crate_type == CrateType::Dylib {
+                diag_handler.warn("LTO with dylibs may not be as effective");
             }
         }