stop hashing nested items, and add a test

src/librustc_incremental/calculate_svh.rs

@@ -182,7 +182,6 @@ mod svh_visitor {
         SawMod,
         SawForeignItem,
         SawItem,
-        SawDecl,
         SawTy,
         SawGenerics,
         SawFn,
@@ -285,24 +284,13 @@ mod svh_visitor {
     /// SawStmtComponent is analogous to SawExprComponent, but for statements.
     #[derive(Hash)]
     pub enum SawStmtComponent {
-        SawStmtDecl,
         SawStmtExpr,
         SawStmtSemi,
     }
 
-    fn saw_stmt(node: &Stmt_) -> SawStmtComponent {
-        match *node {
-            StmtDecl(..) => SawStmtDecl,
-            StmtExpr(..) => SawStmtExpr,
-            StmtSemi(..) => SawStmtSemi,
-        }
-    }
-
     impl<'a, 'tcx> Visitor<'a> for StrictVersionHashVisitor<'a, 'tcx> {
-        fn visit_nested_item(&mut self, item: ItemId) {
-            let def_path = self.tcx.map.def_path_from_id(item.id).unwrap();
-            debug!("visit_nested_item: def_path={:?} st={:?}", def_path, self.st);
-            self.hash_def_path(&def_path);
+        fn visit_nested_item(&mut self, _: ItemId) {
+            // Each item is hashed independently; ignore nested items.
         }
 
         fn visit_variant_data(&mut self, s: &'a VariantData, name: Name,
@@ -362,7 +350,20 @@ mod svh_visitor {
 
         fn visit_stmt(&mut self, s: &'a Stmt) {
             debug!("visit_stmt: st={:?}", self.st);
-            SawStmt(saw_stmt(&s.node)).hash(self.st); visit::walk_stmt(self, s)
+
+            // We don't want to modify the hash for decls, because
+            // they might be item decls (if they are local decls,
+            // we'll hash that fact in visit_local); but we do want to
+            // remember if this was a StmtExpr or StmtSemi (the later
+            // had an explicit semi-colon; this affects the typing
+            // rules).
+            match s.node {
+                StmtDecl(..) => (),
+                StmtExpr(..) => SawStmt(SawStmtExpr).hash(self.st),
+                StmtSemi(..) => SawStmt(SawStmtSemi).hash(self.st),
+            }
+
+            visit::walk_stmt(self, s)
         }
 
         fn visit_foreign_item(&mut self, i: &'a ForeignItem) {
@@ -390,11 +391,6 @@ mod svh_visitor {
             SawMod.hash(self.st); visit::walk_mod(self, m, n)
         }
 
-        fn visit_decl(&mut self, d: &'a Decl) {
-            debug!("visit_decl: st={:?}", self.st);
-            SawDecl.hash(self.st); visit::walk_decl(self, d)
-        }
-
         fn visit_ty(&mut self, t: &'a Ty) {
             debug!("visit_ty: st={:?}", self.st);
             SawTy.hash(self.st); visit::walk_ty(self, t)

src/test/incremental/ich_nested_items.rs

@@ -0,0 +1,36 @@
+// Copyright 2014 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.
+
+// Check that the hash of `foo` doesn't change just because we ordered
+// the nested items (or even added new ones).
+
+// revisions: rpass1 rpass2
+
+#![feature(rustc_attrs)]
+
+#[cfg(rpass1)]
+fn foo() {
+    fn bar() { }
+    fn baz() { }
+}
+
+#[cfg(rpass2)]
+#[rustc_clean(label="Hir", cfg="rpass2")]
+fn foo() {
+    #[rustc_clean(label="Hir", cfg="rpass2")]
+    fn baz() { } // order is different...
+
+    #[rustc_clean(label="Hir", cfg="rpass2")]
+    fn bar() { } // but that doesn't matter.
+
+    fn bap() { } // neither does adding a new item
+}
+
+fn main() { }