do not emit #[no_mangle] on extern functions

Author: fw-immunant

c2rust-transpile/src/translator/mod.rs

@@ -403,7 +403,11 @@ pub fn stmts_block(mut stmts: Vec<Stmt>) -> P<Block> {
 // values.
 fn mk_linkage(in_extern_block: bool, new_name: &str, old_name: &str) -> Builder {
     if new_name == old_name {
-        mk() // Don't touch my name Rust!
+        if in_extern_block {
+            mk() // There is no mangling by default in extern blocks anymore
+        } else {
+            mk().single_attr("no_mangle") // Don't touch my name Rust!
+        }
     } else if in_extern_block {
         mk().str_attr("link_name", old_name) // Look for this name
     } else {

tests/items/src/test_fn_attrs.rs

@@ -52,6 +52,6 @@ pub fn test_fn_attrs() {
 
     if cfg!(not(target_os = "macos")) {
         // aliased_fn is aliased to the inline_extern function
-        assert!(src.contains("#[no_mangle]\n    #[link_name = \"inline_extern\"]\n    fn aliased_fn();"));
+        assert!(src.contains("extern \"C\" {\n    #[link_name = \"inline_extern\"]\n    fn aliased_fn();"));
     }
 }

tests/statics/src/test_sections.rs

@@ -50,6 +50,6 @@ pub fn test_sectioned_used_static() {
 
         // This static is pub, but we want to ensure it has attributes applied
         assert!(src.contains("#[link_section = \"fb\"]\npub static mut rust_initialized_extern: libc::c_int = 1 as libc::c_int;"));
-        assert!(src.contains("#[no_mangle]\n    #[link_name = \"no_attrs\"]\n    static mut rust_aliased_static: libc::c_int;"))
+        assert!(src.contains("extern \"C\" {\n    #[link_name = \"no_attrs\"]\n    static mut rust_aliased_static: libc::c_int;"))
     }
 }