Almost fix i686

Author: mati865

compiler/rustc_codegen_llvm/src/back/archive.rs

@@ -164,7 +164,7 @@ impl<'a> ArchiveBuilder<'a> for LlvmArchiveBuilder<'a> {
             .iter()
             .map(|import: &DllImport| {
                 if self.config.sess.target.arch == "x86" {
-                    LlvmArchiveBuilder::i686_decorated_name(import).into_string().unwrap()
+                    LlvmArchiveBuilder::i686_decorated_name(import, true).into_string().unwrap()
                 } else {
                     import.name.to_string()
                 }
@@ -320,13 +320,17 @@ impl<'a> LlvmArchiveBuilder<'a> {
         }
     }
 
-    fn i686_decorated_name(import: &DllImport) -> CString {
+    fn i686_decorated_name(import: &DllImport, mingw: bool) -> CString {
         let name = import.name;
+        // MinGW doesn't want `_` prefix for `.def` file
+        let prefix = if mingw { "" } else { "_" };
         // We verified during construction that `name` does not contain any NULL characters, so the
         // conversion to CString is guaranteed to succeed.
         CString::new(match import.calling_convention {
-            DllCallingConvention::C => format!("_{}", name),
-            DllCallingConvention::Stdcall(arg_list_size) => format!("_{}@{}", name, arg_list_size),
+            DllCallingConvention::C => format!("{}{}", prefix, name),
+            DllCallingConvention::Stdcall(arg_list_size) => {
+                format!("{}{}@{}", prefix, name, arg_list_size)
+            }
             DllCallingConvention::Fastcall(arg_list_size) => format!("@{}@{}", name, arg_list_size),
             DllCallingConvention::Vectorcall(arg_list_size) => {
                 format!("{}@@{}", name, arg_list_size)

src/test/run-make/raw-dylib-alt-calling-convention/Makefile

@@ -1,12 +1,12 @@
 # Test the behavior of #[link(.., kind = "raw-dylib")] with alternative calling conventions.
 
-# only-i686-pc-windows-msvc
+# only-i686-pc-windows-gnu
 
 -include ../../run-make-fulldeps/tools.mk
 
 all:
 	$(call COMPILE_OBJ,"$(TMPDIR)"/extern.obj,extern.c)
-	$(CC) "$(TMPDIR)"/extern.obj -link -dll -out:"$(TMPDIR)"/extern.dll
+	$(CC) "$(TMPDIR)"/extern.obj -shared -o "$(TMPDIR)"/extern.dll
 	$(RUSTC) --crate-type lib --crate-name raw_dylib_alt_calling_convention_test lib.rs
 	$(RUSTC) --crate-type bin driver.rs -L "$(TMPDIR)"
 	"$(TMPDIR)"/driver > "$(TMPDIR)"/output.txt