librustc: Ensure that type parameters are in the right positions in paths.

This removes the stacking of type parameters that occurs when invoking
trait methods, and fixes all places in the standard library that were
relying on it. It is somewhat awkward in places; I think we'll probably
want something like the `Foo::<for T>::new()` syntax.

2 files changed, 49 insertions, 9 deletions

diff --git a/src/libsyntax/ext/build.rs b/src/libsyntax/ext/build.rs
index a62a1d121e2..21d67493cbf 100644
--- a/src/libsyntax/ext/build.rs
+++ b/src/libsyntax/ext/build.rs
@@ -74,6 +74,13 @@ pub trait AstBuilder {
     // statements
     fn stmt_expr(&self, expr: @ast::expr) -> @ast::stmt;
     fn stmt_let(&self, sp: span, mutbl: bool, ident: ast::ident, ex: @ast::expr) -> @ast::stmt;
+    fn stmt_let_typed(&self,
+                      sp: span,
+                      mutbl: bool,
+                      ident: ast::ident,
+                      typ: ast::Ty,
+                      ex: @ast::expr)
+                      -> @ast::stmt;
 
     // blocks
     fn block(&self, span: span, stmts: ~[@ast::stmt], expr: Option<@ast::expr>) -> ast::Block;
@@ -241,8 +248,8 @@ impl AstBuilder for @ExtCtxt {
                 types: ~[ast::Ty])
                 -> ast::Path {
         let last_identifier = idents.pop();
-        let mut segments: ~[ast::PathSegment] = idents.consume_iter()
-                                                      .transform(|ident| {
+        let mut segments: ~[ast::PathSegment] = idents.move_iter()
+                                                      .map(|ident| {
             ast::PathSegment {
                 identifier: ident,
                 lifetime: None,
@@ -400,6 +407,26 @@ impl AstBuilder for @ExtCtxt {
         @respan(sp, ast::stmt_decl(@decl, self.next_id()))
     }
 
+    fn stmt_let_typed(&self,
+                      sp: span,
+                      mutbl: bool,
+                      ident: ast::ident,
+                      typ: ast::Ty,
+                      ex: @ast::expr)
+                      -> @ast::stmt {
+        let pat = self.pat_ident(sp, ident);
+        let local = @ast::Local {
+            is_mutbl: mutbl,
+            ty: typ,
+            pat: pat,
+            init: Some(ex),
+            id: self.next_id(),
+            span: sp,
+        };
+        let decl = respan(sp, ast::decl_local(local));
+        @respan(sp, ast::stmt_decl(@decl, self.next_id()))
+    }
+
     fn block(&self, span: span, stmts: ~[@ast::stmt], expr: Option<@expr>) -> ast::Block {
         self.block_all(span, ~[], stmts, expr)
     }
diff --git a/src/libsyntax/ext/deriving/rand.rs b/src/libsyntax/ext/deriving/rand.rs
index e55a96f77ff..9f86fe7d7f2 100644
--- a/src/libsyntax/ext/deriving/rand.rs
+++ b/src/libsyntax/ext/deriving/rand.rs
@@ -76,24 +76,34 @@ fn rand_substructure(cx: @ExtCtxt, span: span, substr: &Substructure) -> @expr {
 
             let variant_count = cx.expr_uint(span, variants.len());
 
-            // need to specify the uint-ness of the random number
-            let uint_ty = cx.ty_ident(span, cx.ident_of("uint"));
             let r_ty = cx.ty_ident(span, cx.ident_of("R"));
             let rand_name = cx.path_all(span,
                                         true,
                                         rand_ident.clone(),
                                         None,
-                                        ~[ uint_ty, r_ty ]);
+                                        ~[]);
             let rand_name = cx.expr_path(rand_name);
 
-            // ::std::rand::Rand::rand::<uint>(rng)
+            // ::std::rand::Rand::rand(rng)
             let rv_call = cx.expr_call(span,
                                        rand_name,
                                        ~[ rng[0].duplicate(cx) ]);
 
+            // need to specify the uint-ness of the random number
+            let uint_ty = cx.ty_ident(span, cx.ident_of("uint"));
+            let value_ident = cx.ident_of("__value");
+            let let_statement = cx.stmt_let_typed(span,
+                                                  false,
+                                                  value_ident,
+                                                  uint_ty,
+                                                  rv_call);
+
             // rand() % variants.len()
-            let rand_variant = cx.expr_binary(span, ast::rem,
-                                              rv_call, variant_count);
+            let value_ref = cx.expr_ident(span, value_ident);
+            let rand_variant = cx.expr_binary(span,
+                                              ast::rem,
+                                              value_ref,
+                                              variant_count);
 
             let mut arms = do variants.iter().enumerate().map |(i, id_sum)| {
                 let i_expr = cx.expr_uint(span, i);
@@ -111,7 +121,10 @@ fn rand_substructure(cx: @ExtCtxt, span: span, substr: &Substructure) -> @expr {
             // _ => {} at the end. Should never occur
             arms.push(cx.arm_unreachable(span));
 
-            cx.expr_match(span, rand_variant, arms)
+            let match_expr = cx.expr_match(span, rand_variant, arms);
+
+            let block = cx.block(span, ~[ let_statement ], Some(match_expr));
+            cx.expr_block(block)
         }
         _ => cx.bug("Non-static method in `deriving(Rand)`")
     };