refactor: remove obsolete tranform let_x_uninitialized (#1613)

`let_x_uninitialized` is obsolete since the transpiler now initializes
everything. This is also an old transform, using the deprecated
`mem::uninitialized` instead of `MaybeUninit`, and not wrapping it in
`unsafe` either. Furthermore, the `let_x_uninitialized.rs` test didn't
compile since the variables were untyped.

Author: kkysen

c2rust-refactor/src/transform/vars.rs

@@ -15,34 +15,12 @@ use crate::ast_manip::{MutVisit, MutVisitNodes, fold_blocks, visit_nodes};
 use crate::command::{CommandState, DriverCommand, Registry};
 use crate::driver::{Phase};
 use crate::match_or;
-use crate::matcher::{MatchCtxt, Subst, mut_visit_match_with, replace_stmts};
+use crate::matcher::{MatchCtxt, Subst, mut_visit_match_with};
 use crate::reflect::reflect_tcx_ty;
 use crate::transform::Transform;
 use crate::RefactorCtxt;
 
 
-/// # `let_x_uninitialized` Command
-///
-/// Obsolete - the translator now does this automatically.
-///
-/// Usage: `let_x_uninitialized`
-///
-/// For each local variable that is uninitialized (`let x;`), add
-/// `mem::uninitialized()` as an initializer expression.
-pub struct LetXUninitialized;
-
-impl Transform for LetXUninitialized {
-    fn transform(&self, krate: &mut Crate, st: &CommandState, cx: &RefactorCtxt) {
-        replace_stmts(st, cx, krate,
-                                  "let __pat;",
-                                  "let __pat = ::std::mem::uninitialized();");
-        replace_stmts(st, cx, krate,
-                                  "let __pat: __ty;",
-                                  "let __pat: __ty = ::std::mem::uninitialized();");
-    }
-}
-
-
 /// # `sink_lets` Command
 ///
 /// Usage: `sink_lets`
@@ -570,7 +548,6 @@ fn expand_local_ptr_tys(st: &CommandState, cx: &RefactorCtxt) {
 pub fn register_commands(reg: &mut Registry) {
     use super::mk;
 
-    reg.register("let_x_uninitialized", |_args| mk(LetXUninitialized));
     reg.register("sink_lets", |_args| mk(SinkLets));
     reg.register("fold_let_assign", |_args| mk(FoldLetAssign));
     reg.register("uninit_to_default", |_args| mk(UninitToDefault));

c2rust-refactor/tests/snapshots.rs

@@ -82,6 +82,7 @@ impl<'a> RefactorTest<'a> {
         }
     }
 
+    #[allow(unused)] // TODO remove when used
     pub fn expect_compile_error(self, expect_error: bool) -> Self {
         self.old_expect_compile_error(expect_error)
             .new_expect_compile_error(expect_error)
@@ -249,13 +250,6 @@ fn test_fold_let_assign() {
     refactor("fold_let_assign").test();
 }
 
-#[test]
-fn test_let_x_uninitialized() {
-    refactor("let_x_uninitialized")
-        .expect_compile_error(true)
-        .test();
-}
-
 #[test]
 fn test_reconstruct_while() {
     refactor("reconstruct_while").test();