Rollup merge of #36438 - jseyfried:node_ids_in_expansion, r=nrc

Assign node ids during macro expansion

After this PR,
 - The `ExtCtxt` can access `resolve`'s `Resolver` through the trait object `ext::base::Resolver`.
  - The `Resolver` trait object can load macros and replaces today's `MacroLoader` trait object.
  - The macro expander uses the `Resolver` trait object to resolve macro invocations.
 - The macro expander assigns node ids and builds the `Resolver`'s `macros_at_scope` map.
   - This is groundwork for merging import resolution and expansion.
 - Performance of expansion together with node id assignment improves by ~5%.

**EDIT:** Since Github is reordering the commits, here is `git log`:
 - b54e1e3997: Differentiate between monotonic and non-monotonic expansion and only assign node ids during monotonic expansion.
 - 78c0039878: Expand generated test harnesses and macro registries.
 - f3c2dca353: Remove scope placeholders from the crate root.
 - c86c8d41a2: Perform node id assignment and `macros_at_scope` construction during the `InvocationCollector` and `PlaceholderExpander` folds.
 - 72a636975f: Move macro resolution into `librustc_resolve`.
 - 20b43b2323: Rewrite the unit tests in `ext/expand.rs` as a `compile-fail` test.
 - a9821e1658: Refactor `ExtCtxt` to use a `Resolver` instead of a `MacroLoader`.
 - 60440b226d: Refactor `noop_fold_stmt_kind` out of `noop_fold_stmt`.
 - 50f94f6c95: Avoid needless reexpansions.

r? @nrc

src/test/compile-fail-fulldeps/qquote.rs

@@ -22,11 +22,11 @@ use syntax_pos::DUMMY_SP;
 
 fn main() {
     let ps = syntax::parse::ParseSess::new();
-    let mut loader = syntax::ext::base::DummyMacroLoader;
+    let mut resolver = syntax::ext::base::DummyResolver;
     let mut cx = syntax::ext::base::ExtCtxt::new(
         &ps, vec![],
         syntax::ext::expand::ExpansionConfig::default("qquote".to_string()),
-        &mut loader);
+        &mut resolver);
     cx.bt_push(syntax::codemap::ExpnInfo {
         call_site: DUMMY_SP,
         callee: syntax::codemap::NameAndSpan {

src/test/compile-fail/macro-expansion-tests.rs

@@ -0,0 +1,46 @@
+// Copyright 2016 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+mod macros_cant_escape_fns {
+    fn f() {
+        macro_rules! m { () => { 3 + 4 } }
+    }
+    fn g() -> i32 { m!() } //~ ERROR macro undefined
+}
+
+mod macros_cant_escape_mods {
+    mod f {
+        macro_rules! m { () => { 3 + 4 } }
+    }
+    fn g() -> i32 { m!() } //~ ERROR macro undefined
+}
+
+mod macros_can_escape_flattened_mods_test {
+    #[macro_use]
+    mod f {
+        macro_rules! m { () => { 3 + 4 } }
+    }
+    fn g() -> i32 { m!() }
+}
+
+fn macro_tokens_should_match() {
+    macro_rules! m { (a) => { 13 } }
+    m!(a);
+}
+
+// should be able to use a bound identifier as a literal in a macro definition:
+fn self_macro_parsing() {
+    macro_rules! foo { (zz) => { 287; } }
+    fn f(zz: i32) {
+        foo!(zz);
+    }
+}
+
+fn main() {}

src/test/run-fail-fulldeps/qquote.rs

@@ -25,11 +25,11 @@ use syntax_pos::DUMMY_SP;
 
 fn main() {
     let ps = syntax::parse::ParseSess::new();
-    let mut loader = syntax::ext::base::DummyMacroLoader;
+    let mut resolver = syntax::ext::base::DummyResolver;
     let mut cx = syntax::ext::base::ExtCtxt::new(
         &ps, vec![],
         syntax::ext::expand::ExpansionConfig::default("qquote".to_string()),
-        &mut loader);
+        &mut resolver);
     cx.bt_push(syntax::codemap::ExpnInfo {
         call_site: DUMMY_SP,
         callee: syntax::codemap::NameAndSpan {

src/test/run-pass-fulldeps/qquote.rs

@@ -21,11 +21,11 @@ use syntax_pos::DUMMY_SP;
 
 fn main() {
     let ps = syntax::parse::ParseSess::new();
-    let mut loader = syntax::ext::base::DummyMacroLoader;
+    let mut resolver = syntax::ext::base::DummyResolver;
     let mut cx = syntax::ext::base::ExtCtxt::new(
         &ps, vec![],
         syntax::ext::expand::ExpansionConfig::default("qquote".to_string()),
-        &mut loader);
+        &mut resolver);
     cx.bt_push(syntax::codemap::ExpnInfo {
         call_site: DUMMY_SP,
         callee: syntax::codemap::NameAndSpan {