Remove broken smallvec dependency

tests/test_precedence.rs

@@ -15,7 +15,6 @@
 //! 5. Compare the expressions with one another, if they are not equal fail.
 
 extern crate rustc_data_structures;
-extern crate smallvec;
 extern crate syntax;
 extern crate syntax_pos;
 
@@ -24,7 +23,6 @@ mod features;
 use quote::quote;
 use rayon::iter::{IntoParallelIterator, ParallelIterator};
 use regex::Regex;
-use smallvec::smallvec;
 use syntax::ast;
 use syntax::ptr::P;
 use syntax_pos::edition::Edition;
@@ -211,16 +209,57 @@ fn libsyntax_parse_and_rewrite(input: &str) -> Option<P<ast::Expr>> {
 /// This method operates on libsyntax objects.
 fn libsyntax_brackets(mut libsyntax_expr: P<ast::Expr>) -> Option<P<ast::Expr>> {
     use rustc_data_structures::thin_vec::ThinVec;
-    use smallvec::SmallVec;
     use std::mem;
-    use syntax::ast::{Expr, ExprKind, Field, Mac, Pat, Stmt, StmtKind, Ty};
-    use syntax::mut_visit::{noop_visit_expr, MutVisitor};
+    use syntax::ast::{Block, Expr, ExprKind, Field, Mac, Pat, Stmt, StmtKind, Ty};
+    use syntax::mut_visit::MutVisitor;
+    use syntax::util::map_in_place::MapInPlace;
     use syntax_pos::DUMMY_SP;
 
     struct BracketsVisitor {
         failed: bool,
     };
 
+    fn flat_map_field<T: MutVisitor>(mut f: Field, vis: &mut T) -> Vec<Field> {
+        if f.is_shorthand {
+            noop_visit_expr(&mut f.expr, vis);
+        } else {
+            vis.visit_expr(&mut f.expr);
+        }
+        vec![f]
+    }
+
+    fn flat_map_stmt<T: MutVisitor>(stmt: Stmt, vis: &mut T) -> Vec<Stmt> {
+        let kind = match stmt.kind {
+            // Don't wrap toplevel expressions in statements.
+            StmtKind::Expr(mut e) => {
+                noop_visit_expr(&mut e, vis);
+                StmtKind::Expr(e)
+            }
+            StmtKind::Semi(mut e) => {
+                noop_visit_expr(&mut e, vis);
+                StmtKind::Semi(e)
+            }
+            s => s,
+        };
+
+        vec![Stmt { kind, ..stmt }]
+    }
+
+    fn noop_visit_expr<T: MutVisitor>(e: &mut Expr, vis: &mut T) {
+        use syntax::mut_visit::{noop_visit_expr, visit_opt, visit_thin_attrs};
+        match &mut e.kind {
+            ExprKind::Struct(path, fields, expr) => {
+                vis.visit_path(path);
+                fields.flat_map_in_place(|field| flat_map_field(field, vis));
+                visit_opt(expr, |expr| vis.visit_expr(expr));
+                vis.visit_id(&mut e.id);
+                vis.visit_span(&mut e.span);
+                visit_thin_attrs(&mut e.attrs, vis);
+            }
+            _ => noop_visit_expr(e, vis),
+        }
+    }
+
     impl MutVisitor for BracketsVisitor {
         fn visit_expr(&mut self, e: &mut P<Expr>) {
             noop_visit_expr(e, self);
@@ -241,13 +280,10 @@ fn libsyntax_brackets(mut libsyntax_expr: P<ast::Expr>) -> Option<P<ast::Expr>>
             }
         }
 
-        fn flat_map_field(&mut self, mut f: Field) -> SmallVec<[Field; 1]> {
-            if f.is_shorthand {
-                noop_visit_expr(&mut f.expr, self);
-            } else {
-                self.visit_expr(&mut f.expr);
-            }
-            SmallVec::from([f])
+        fn visit_block(&mut self, block: &mut P<Block>) {
+            self.visit_id(&mut block.id);
+            block.stmts.flat_map_in_place(|stmt| flat_map_stmt(stmt, self));
+            self.visit_span(&mut block.span);
         }
 
         // We don't want to look at expressions that might appear in patterns or
@@ -261,23 +297,6 @@ fn libsyntax_brackets(mut libsyntax_expr: P<ast::Expr>) -> Option<P<ast::Expr>>
             let _ = ty;
         }
 
-        fn flat_map_stmt(&mut self, stmt: Stmt) -> SmallVec<[Stmt; 1]> {
-            let kind = match stmt.kind {
-                // Don't wrap toplevel expressions in statements.
-                StmtKind::Expr(mut e) => {
-                    noop_visit_expr(&mut e, self);
-                    StmtKind::Expr(e)
-                }
-                StmtKind::Semi(mut e) => {
-                    noop_visit_expr(&mut e, self);
-                    StmtKind::Semi(e)
-                }
-                s => s,
-            };
-
-            smallvec![Stmt { kind, ..stmt }]
-        }
-
         fn visit_mac(&mut self, mac: &mut Mac) {
             // By default when folding over macros, libsyntax panics. This is
             // because it's usually not what you want, you want to run after