Introduce marker types for indicating variance and for opting out

of builtin bounds.

Fixes #10834.
Fixes #11385.
cc #5922.

Author: nikomatsakis

src/libarena/lib.rs

@@ -33,6 +33,7 @@ use std::cast;
 use std::cell::{Cell, RefCell};
 use std::num;
 use std::ptr;
+use std::kinds::marker;
 use std::mem;
 use std::rt::global_heap;
 use std::uint;
@@ -71,14 +72,14 @@ struct Chunk {
 // different chunks than objects without destructors. This reduces
 // overhead when initializing plain-old-data and means we don't need
 // to waste time running the destructors of POD.
-#[no_freeze]
 pub struct Arena {
     // The head is separated out from the list as a unbenchmarked
     // microoptimization, to avoid needing to case on the list to
     // access the head.
     priv head: Chunk,
     priv pod_head: Chunk,
     priv chunks: RefCell<@List<Chunk>>,
+    priv no_freeze: marker::NoFreeze,
 }
 
 impl Arena {
@@ -91,6 +92,7 @@ impl Arena {
             head: chunk(initial_size, false),
             pod_head: chunk(initial_size, true),
             chunks: RefCell::new(@Nil),
+            no_freeze: marker::NoFreeze,
         }
     }
 }

src/libextra/arc.rs

@@ -45,6 +45,7 @@ use sync;
 use sync::{Mutex, RWLock};
 
 use std::cast;
+use std::kinds::marker;
 use std::sync::arc::UnsafeArc;
 use std::task;
 
@@ -150,17 +151,19 @@ impl<T:Freeze + Send> Clone for Arc<T> {
 struct MutexArcInner<T> { lock: Mutex, failed: bool, data: T }
 
 /// An Arc with mutable data protected by a blocking mutex.
-#[no_freeze]
-pub struct MutexArc<T> { priv x: UnsafeArc<MutexArcInner<T>> }
-
+pub struct MutexArc<T> {
+    priv x: UnsafeArc<MutexArcInner<T>>,
+    priv marker: marker::NoFreeze,
+}
 
 impl<T:Send> Clone for MutexArc<T> {
     /// Duplicate a mutex-protected Arc. See arc::clone for more details.
     #[inline]
     fn clone(&self) -> MutexArc<T> {
         // NB: Cloning the underlying mutex is not necessary. Its reference
         // count would be exactly the same as the shared state's.
-        MutexArc { x: self.x.clone() }
+        MutexArc { x: self.x.clone(),
+                   marker: marker::NoFreeze, }
     }
 }
 
@@ -179,7 +182,8 @@ impl<T:Send> MutexArc<T> {
             lock: Mutex::new_with_condvars(num_condvars),
             failed: false, data: user_data
         };
-        MutexArc { x: UnsafeArc::new(data) }
+        MutexArc { x: UnsafeArc::new(data),
+                   marker: marker::NoFreeze, }
     }
 
     /**
@@ -318,16 +322,17 @@ struct RWArcInner<T> { lock: RWLock, failed: bool, data: T }
  *
  * Unlike mutex_arcs, rw_arcs are safe, because they cannot be nested.
  */
-#[no_freeze]
 pub struct RWArc<T> {
     priv x: UnsafeArc<RWArcInner<T>>,
+    priv marker: marker::NoFreeze,
 }
 
 impl<T:Freeze + Send> Clone for RWArc<T> {
     /// Duplicate a rwlock-protected Arc. See arc::clone for more details.
     #[inline]
     fn clone(&self) -> RWArc<T> {
-        RWArc { x: self.x.clone() }
+        RWArc { x: self.x.clone(),
+                marker: marker::NoFreeze, }
     }
 
 }
@@ -347,7 +352,8 @@ impl<T:Freeze + Send> RWArc<T> {
             lock: RWLock::new_with_condvars(num_condvars),
             failed: false, data: user_data
         };
-        RWArc { x: UnsafeArc::new(data), }
+        RWArc { x: UnsafeArc::new(data),
+                marker: marker::NoFreeze, }
     }
 
     /**

src/librustc/middle/lang_items.rs

@@ -273,4 +273,17 @@ lets_do_this! {
     37, ManagedHeapLangItem,             "managed_heap",            managed_heap;
     38, ExchangeHeapLangItem,            "exchange_heap",           exchange_heap;
     39, GcLangItem,                      "gc",                      gc;
+
+    40, CovariantTypeItem,               "covariant_type",          covariant_type;
+    41, ContravariantTypeItem,           "contravariant_type",      contravariant_type;
+    42, InvariantTypeItem,               "invariant_type",          invariant_type;
+
+    43, CovariantLifetimeItem,           "covariant_lifetime",      covariant_lifetime;
+    44, ContravariantLifetimeItem,       "contravariant_lifetime",  contravariant_lifetime;
+    45, InvariantLifetimeItem,           "invariant_lifetime",      invariant_lifetime;
+
+    46, NoFreezeItem,                    "no_freeze_bound",         no_freeze_bound;
+    47, NoSendItem,                      "no_send_bound",           no_send_bound;
+    48, NoPodItem,                       "no_pod_bound",            no_pod_bound;
+    49, ManagedItem,                     "managed_bound",           managed_bound;
 }

src/librustc/middle/lint.rs

@@ -957,8 +957,8 @@ static other_attrs: &'static [&'static str] = &[
     "thread_local", // for statics
     "allow", "deny", "forbid", "warn", // lint options
     "deprecated", "experimental", "unstable", "stable", "locked", "frozen", //item stability
-    "crate_map", "cfg", "doc", "export_name", "link_section", "no_freeze",
-    "no_mangle", "no_send", "static_assert", "unsafe_no_drop_flag", "packed",
+    "crate_map", "cfg", "doc", "export_name", "link_section",
+    "no_mangle", "static_assert", "unsafe_no_drop_flag", "packed",
     "simd", "repr", "deriving", "unsafe_destructor", "link", "phase",
     "macro_export", "must_use",
 

src/librustc/middle/trans/base.rs

@@ -328,7 +328,7 @@ pub fn at_box_body(bcx: &Block, body_t: ty::t, boxptr: ValueRef) -> ValueRef {
 // malloc_raw_dyn: allocates a box to contain a given type, but with a
 // potentially dynamic size.
 pub fn malloc_raw_dyn<'a>(
-                      bcx: &'a Block,
+                      bcx: &'a Block<'a>,
                       t: ty::t,
                       heap: heap,
                       size: ValueRef)
@@ -425,7 +425,7 @@ pub fn malloc_general_dyn<'a>(
     }
 }
 
-pub fn malloc_general<'a>(bcx: &'a Block, t: ty::t, heap: heap)
+pub fn malloc_general<'a>(bcx: &'a Block<'a>, t: ty::t, heap: heap)
                       -> MallocResult<'a> {
     let ty = type_of(bcx.ccx(), t);
     assert!(heap != heap_exchange);
@@ -1230,18 +1230,19 @@ pub fn make_return_pointer(fcx: &FunctionContext, output_type: ty::t)
 //
 // Be warned! You must call `init_function` before doing anything with the
 // returned function context.
-pub fn new_fn_ctxt_detailed(ccx: @CrateContext,
-                            path: ast_map::Path,
-                            llfndecl: ValueRef,
-                            id: ast::NodeId,
-                            has_env: bool,
-                            output_type: ty::t,
-                            param_substs: Option<@param_substs>,
-                            sp: Option<Span>)
-                            -> FunctionContext {
+pub fn new_fn_ctxt<'a>(ccx: @CrateContext,
+                       path: ast_map::Path,
+                       llfndecl: ValueRef,
+                       id: ast::NodeId,
+                       has_env: bool,
+                       output_type: ty::t,
+                       param_substs: Option<@param_substs>,
+                       sp: Option<Span>,
+                       block_arena: &'a TypedArena<Block<'a>>)
+                       -> FunctionContext<'a> {
     for p in param_substs.iter() { p.validate(); }
 
-    debug!("new_fn_ctxt_detailed(path={},
+    debug!("new_fn_ctxt(path={},
            id={:?}, \
            param_substs={})",
            path_str(ccx.sess, path),
@@ -1258,25 +1259,25 @@ pub fn new_fn_ctxt_detailed(ccx: @CrateContext,
     let debug_context = debuginfo::create_function_debug_context(ccx, id, param_substs, llfndecl);
 
     let mut fcx = FunctionContext {
-        llfn: llfndecl,
-        llenv: None,
-        llretptr: Cell::new(None),
-        entry_bcx: RefCell::new(None),
-        alloca_insert_pt: Cell::new(None),
-        llreturn: Cell::new(None),
-        personality: Cell::new(None),
-        caller_expects_out_pointer: uses_outptr,
-        llargs: RefCell::new(HashMap::new()),
-        lllocals: RefCell::new(HashMap::new()),
-        llupvars: RefCell::new(HashMap::new()),
-        id: id,
-        param_substs: param_substs,
-        span: sp,
-        path: path,
-        block_arena: TypedArena::new(),
-        ccx: ccx,
-        debug_context: debug_context,
-        scopes: RefCell::new(~[])
+          llfn: llfndecl,
+          llenv: None,
+          llretptr: Cell::new(None),
+          entry_bcx: RefCell::new(None),
+          alloca_insert_pt: Cell::new(None),
+          llreturn: Cell::new(None),
+          personality: Cell::new(None),
+          caller_expects_out_pointer: uses_outptr,
+          llargs: RefCell::new(HashMap::new()),
+          lllocals: RefCell::new(HashMap::new()),
+          llupvars: RefCell::new(HashMap::new()),
+          id: id,
+          param_substs: param_substs,
+          span: sp,
+          path: path,
+          block_arena: block_arena,
+          ccx: ccx,
+          debug_context: debug_context,
+          scopes: RefCell::new(~[])
     };
 
     if has_env {
@@ -1328,18 +1329,6 @@ pub fn init_function<'a>(
     }
 }
 
-pub fn new_fn_ctxt(ccx: @CrateContext,
-                   path: ast_map::Path,
-                   llfndecl: ValueRef,
-                   has_env: bool,
-                   output_type: ty::t,
-                   sp: Option<Span>)
-                   -> FunctionContext {
-    // FIXME(#11385): Do not call `init_function` here; it will typecheck
-    // but segfault.
-    new_fn_ctxt_detailed(ccx, path, llfndecl, -1, has_env, output_type, None, sp)
-}
-
 // NB: must keep 4 fns in sync:
 //
 //  - type_of_fn
@@ -1411,7 +1400,8 @@ fn copy_args_to_allocas<'a>(fcx: &FunctionContext<'a>,
 
 // Ties up the llstaticallocas -> llloadenv -> lltop edges,
 // and builds the return block.
-pub fn finish_fn(fcx: &FunctionContext, last_bcx: &Block) {
+pub fn finish_fn<'a>(fcx: &'a FunctionContext<'a>,
+                     last_bcx: &'a Block<'a>) {
     let _icx = push_ctxt("finish_fn");
 
     let ret_cx = match fcx.llreturn.get() {
@@ -1469,7 +1459,7 @@ pub fn trans_closure<'a>(ccx: @CrateContext,
                          id: ast::NodeId,
                          _attributes: &[ast::Attribute],
                          output_type: ty::t,
-                         maybe_load_env: |&'a Block<'a>| -> &'a Block<'a>) {
+                         maybe_load_env: <'b> |&'b Block<'b>| -> &'b Block<'b>) {
     ccx.stats.n_closures.set(ccx.stats.n_closures.get() + 1);
 
     let _icx = push_ctxt("trans_closure");
@@ -1483,8 +1473,16 @@ pub fn trans_closure<'a>(ccx: @CrateContext,
         _ => false
     };
 
-    let fcx = new_fn_ctxt_detailed(ccx, path, llfndecl, id, has_env, output_type,
-                                   param_substs, Some(body.span));
+    let arena = TypedArena::new();
+    let fcx = new_fn_ctxt(ccx,
+                          path,
+                          llfndecl,
+                          id,
+                          has_env,
+                          output_type,
+                          param_substs,
+                          Some(body.span),
+                          &arena);
     init_function(&fcx, false, output_type, param_substs);
 
     // cleanup scope for the incoming arguments
@@ -1626,8 +1624,16 @@ fn trans_enum_variant_or_tuple_like_struct(ccx: @CrateContext,
                  ty_to_str(ccx.tcx, ctor_ty)))
     };
 
-    let fcx = new_fn_ctxt_detailed(ccx, ~[], llfndecl, ctor_id, false,
-                                   result_ty, param_substs, None);
+    let arena = TypedArena::new();
+    let fcx = new_fn_ctxt(ccx,
+                          ~[],
+                          llfndecl,
+                          ctor_id,
+                          false,
+                          result_ty,
+                          param_substs,
+                          None,
+                          &arena);
     init_function(&fcx, false, result_ty, param_substs);
 
     let arg_tys = ty::ty_fn_args(ctor_ty);

src/librustc/middle/trans/cleanup.rs

@@ -214,7 +214,7 @@ impl<'a> CleanupMethods<'a> for FunctionContext<'a> {
         self.ccx.tcx.sess.bug("No loop scope found");
     }
 
-    fn normal_exit_block(&self,
+    fn normal_exit_block(&'a self,
                          cleanup_scope: ast::NodeId,
                          exit: uint) -> BasicBlockRef {
         /*!
@@ -226,7 +226,7 @@ impl<'a> CleanupMethods<'a> for FunctionContext<'a> {
         self.trans_cleanups_to_exit_scope(LoopExit(cleanup_scope, exit))
     }
 
-    fn return_exit_block(&self) -> BasicBlockRef {
+    fn return_exit_block(&'a self) -> BasicBlockRef {
         /*!
          * Returns a block to branch to which will perform all pending
          * cleanups and then return from this function
@@ -371,7 +371,7 @@ impl<'a> CleanupMethods<'a> for FunctionContext<'a> {
         scopes.get().iter().rev().any(|s| s.needs_invoke())
     }
 
-    fn get_landing_pad(&self) -> BasicBlockRef {
+    fn get_landing_pad(&'a self) -> BasicBlockRef {
         /*!
          * Returns a basic block to branch to in the event of a failure.
          * This block will run the failure cleanups and eventually
@@ -481,7 +481,7 @@ impl<'a> CleanupHelperMethods<'a> for FunctionContext<'a> {
         f(scopes.get().last().unwrap())
     }
 
-    fn trans_cleanups_to_exit_scope(&self,
+    fn trans_cleanups_to_exit_scope(&'a self,
                                     label: EarlyExitLabel)
                                     -> BasicBlockRef {
         /*!
@@ -641,7 +641,7 @@ impl<'a> CleanupHelperMethods<'a> for FunctionContext<'a> {
         prev_llbb
     }
 
-    fn get_or_create_landing_pad(&self) -> BasicBlockRef {
+    fn get_or_create_landing_pad(&'a self) -> BasicBlockRef {
         /*!
          * Creates a landing pad for the top scope, if one does not
          * exist.  The landing pad will perform all cleanups necessary
@@ -903,10 +903,10 @@ pub trait CleanupMethods<'a> {
                                           custom_scope: CustomScopeIndex)
                                           -> &'a Block<'a>;
     fn top_loop_scope(&self) -> ast::NodeId;
-    fn normal_exit_block(&self,
+    fn normal_exit_block(&'a self,
                          cleanup_scope: ast::NodeId,
                          exit: uint) -> BasicBlockRef;
-    fn return_exit_block(&self) -> BasicBlockRef;
+    fn return_exit_block(&'a self) -> BasicBlockRef;
     fn schedule_drop_mem(&self,
                          cleanup_scope: ScopeId,
                          val: ValueRef,
@@ -929,7 +929,7 @@ pub trait CleanupMethods<'a> {
                                     custom_scope: CustomScopeIndex,
                                     cleanup: ~Cleanup);
     fn needs_invoke(&self) -> bool;
-    fn get_landing_pad(&self) -> BasicBlockRef;
+    fn get_landing_pad(&'a self) -> BasicBlockRef;
 }
 
 trait CleanupHelperMethods<'a> {
@@ -940,10 +940,10 @@ trait CleanupHelperMethods<'a> {
     fn trans_scope_cleanups(&self,
                             bcx: &'a Block<'a>,
                             scope: &CleanupScope<'a>) -> &'a Block<'a>;
-    fn trans_cleanups_to_exit_scope(&self,
+    fn trans_cleanups_to_exit_scope(&'a self,
                                     label: EarlyExitLabel)
                                     -> BasicBlockRef;
-    fn get_or_create_landing_pad(&self) -> BasicBlockRef;
+    fn get_or_create_landing_pad(&'a self) -> BasicBlockRef;
     fn scopes_len(&self) -> uint;
     fn push_scope(&self, scope: CleanupScope<'a>);
     fn pop_scope(&self) -> CleanupScope<'a>;