Auto merge of #33532 - jseyfried:mutable_lowering_context, r=nrc

Clean up `hir::lowering`

Clean up `hir::lowering`:
 - give lowering functions mutable access to the lowering context
 - refactor the `lower_*` functions and other functions that take a lowering context into methods
 - simplify the API that `hir::lowering` exposes to `driver`
 - other miscellaneous cleanups

r? @nrc

src/librustc_driver/driver.rs

@@ -37,7 +37,7 @@
 use rustc_privacy;
 use rustc_plugin::registry::Registry;
 use rustc_plugin as plugin;
-use rustc::hir::lowering::{lower_crate, LoweringContext};
+use rustc::hir::lowering::lower_crate;
 use rustc_passes::{no_asm, loops, consts, rvalues, static_recursion};
 use rustc_const_eval::check_match;
 use super::Compilation;
@@ -816,8 +816,7 @@ pub fn lower_and_resolve<'a>(sess: &Session,
 
         // Lower ast -> hir.
         let hir_forest = time(sess.time_passes(), "lowering ast -> hir", || {
-            let lcx = LoweringContext::new(sess, Some(krate), &mut resolver);
-            hir_map::Forest::new(lower_crate(&lcx, krate), dep_graph)
+            hir_map::Forest::new(lower_crate(krate, sess, &mut resolver), dep_graph)
         });
 
         (ty::CrateAnalysis {

src/librustc_metadata/astencode.rs

@@ -57,7 +57,7 @@
 #[cfg(test)] use syntax::parse;
 #[cfg(test)] use syntax::ast::NodeId;
 #[cfg(test)] use rustc::hir::print as pprust;
-#[cfg(test)] use rustc::hir::lowering::{lower_item, LoweringContext, DummyResolver};
+#[cfg(test)] use rustc::hir::lowering::{LoweringContext, DummyResolver};
 
 struct DecodeContext<'a, 'b, 'tcx: 'a> {
     tcx: TyCtxt<'a, 'tcx, 'tcx>,
@@ -1319,11 +1319,11 @@ fn mk_ctxt() -> parse::ParseSess {
 }
 
 #[cfg(test)]
-fn with_testing_context<T, F: FnOnce(LoweringContext) -> T>(f: F) -> T {
+fn with_testing_context<T, F: FnOnce(&mut LoweringContext) -> T>(f: F) -> T {
     let assigner = FakeNodeIdAssigner;
     let mut resolver = DummyResolver;
-    let lcx = LoweringContext::new(&assigner, None, &mut resolver);
-    f(lcx)
+    let mut lcx = LoweringContext::testing_context(&assigner, &mut resolver);
+    f(&mut lcx)
 }
 
 #[cfg(test)]
@@ -1340,7 +1340,7 @@ fn roundtrip(in_item: hir::Item) {
 fn test_basic() {
     let cx = mk_ctxt();
     with_testing_context(|lcx| {
-        roundtrip(lower_item(&lcx, &quote_item!(&cx,
+        roundtrip(lcx.lower_item(&quote_item!(&cx,
             fn foo() {}
         ).unwrap()));
     });
@@ -1350,7 +1350,7 @@ fn foo() {}
 fn test_smalltalk() {
     let cx = mk_ctxt();
     with_testing_context(|lcx| {
-        roundtrip(lower_item(&lcx, &quote_item!(&cx,
+        roundtrip(lcx.lower_item(&quote_item!(&cx,
             fn foo() -> isize { 3 + 4 } // first smalltalk program ever executed.
         ).unwrap()));
     });
@@ -1360,7 +1360,7 @@ fn foo() -> isize { 3 + 4 } // first smalltalk program ever executed.
 fn test_more() {
     let cx = mk_ctxt();
     with_testing_context(|lcx| {
-        roundtrip(lower_item(&lcx, &quote_item!(&cx,
+        roundtrip(lcx.lower_item(&quote_item!(&cx,
             fn foo(x: usize, y: usize) -> usize {
                 let z = x + y;
                 return z;
@@ -1380,10 +1380,10 @@ fn eq_int(a: isize, b: isize) -> bool { a == b }
     ).unwrap();
     let cx = mk_ctxt();
     with_testing_context(|lcx| {
-        let hir_item = lower_item(&lcx, &item);
+        let hir_item = lcx.lower_item(&item);
         let item_in = InlinedItemRef::Item(&hir_item);
         let item_out = simplify_ast(item_in);
-        let item_exp = InlinedItem::Item(P(lower_item(&lcx, &quote_item!(&cx,
+        let item_exp = InlinedItem::Item(P(lcx.lower_item(&quote_item!(&cx,
             fn new_int_alist<B>() -> alist<isize, B> {
                 return alist {eq_fn: eq_int, data: Vec::new()};
             }

src/librustdoc/test.rs

@@ -28,7 +28,7 @@
 use rustc::session::{self, config};
 use rustc::session::config::{get_unstable_features_setting, OutputType};
 use rustc::session::search_paths::{SearchPaths, PathKind};
-use rustc::hir::lowering::{lower_crate, LoweringContext, DummyResolver};
+use rustc::hir::lowering::{lower_crate, DummyResolver};
 use rustc_back::dynamic_lib::DynamicLibrary;
 use rustc_back::tempdir::TempDir;
 use rustc_driver::{driver, Compilation};
@@ -98,8 +98,7 @@ pub fn run(input: &str,
     let defs = &RefCell::new(hir_map::collect_definitions(&krate));
 
     let mut dummy_resolver = DummyResolver;
-    let lcx = LoweringContext::new(&sess, Some(&krate), &mut dummy_resolver);
-    let krate = lower_crate(&lcx, &krate);
+    let krate = lower_crate(&krate, &sess, &mut dummy_resolver);
 
     let opts = scrape_test_config(&krate);