auto merge of #16933 : nick29581/rust/dst-rvalue, r=nikomatsakis

Closes #16813 

r? @nikomatsakis I feel like I should be checking more things in check_rvalues, but not sure what - I don't properly understand expr_use_visitor

Author: bors

src/librustc/diagnostics.rs

@@ -169,5 +169,6 @@ register_diagnostics!(
     E0157,
     E0158,
     E0159,
-    E0160
+    E0160,
+    E0161
 )

src/librustc/driver/driver.rs

@@ -404,6 +404,9 @@ pub fn phase_3_run_analysis_passes(sess: Session,
     time(time_passes, "borrow checking", (), |_|
          middle::borrowck::check_crate(&ty_cx, krate));
 
+    time(time_passes, "rvalue checking", (), |_|
+         middle::check_rvalues::check_crate(&ty_cx, krate));
+
     time(time_passes, "kind checking", (), |_|
          kind::check_crate(&ty_cx, krate));
 

src/librustc/lib.rs

@@ -80,6 +80,7 @@ pub mod middle {
     pub mod check_const;
     pub mod check_loop;
     pub mod check_match;
+    pub mod check_rvalues;
     pub mod check_static;
     pub mod const_eval;
     pub mod dataflow;

src/librustc/middle/check_rvalues.rs

@@ -0,0 +1,86 @@
+// 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.
+
+// Checks that all rvalues in a crate have statically known size. check_crate
+// is the public starting point.
+
+use middle::expr_use_visitor as euv;
+use middle::mem_categorization as mc;
+use middle::ty;
+use util::ppaux::ty_to_string;
+
+use syntax::ast;
+use syntax::codemap::Span;
+use syntax::visit;
+
+pub fn check_crate(tcx: &ty::ctxt,
+                   krate: &ast::Crate) {
+    let mut rvcx = RvalueContext { tcx: tcx };
+    visit::walk_crate(&mut rvcx, krate, ());
+}
+
+struct RvalueContext<'a> {
+    tcx: &'a ty::ctxt
+}
+
+impl<'a> visit::Visitor<()> for RvalueContext<'a> {
+    fn visit_fn(&mut self,
+                _: &visit::FnKind,
+                fd: &ast::FnDecl,
+                b: &ast::Block,
+                _: Span,
+                _: ast::NodeId,
+                _: ()) {
+        let mut euv = euv::ExprUseVisitor::new(self, self.tcx);
+        euv.walk_fn(fd, b);
+    }
+}
+
+impl<'a> euv::Delegate for RvalueContext<'a> {
+    fn consume(&mut self,
+               _: ast::NodeId,
+               span: Span,
+               cmt: mc::cmt,
+               _: euv::ConsumeMode) {
+        debug!("consume; cmt: {:?}; type: {}", *cmt, ty_to_string(self.tcx, cmt.ty));
+        if !ty::type_is_sized(self.tcx, cmt.ty) {
+            span_err!(self.tcx.sess, span, E0161,
+                "cannot move a value of type {0}: the size of {0} cannot be statically determined",
+                ty_to_string(self.tcx, cmt.ty));
+        }
+    }
+
+    fn consume_pat(&mut self,
+                   _consume_pat: &ast::Pat,
+                   _cmt: mc::cmt,
+                   _mode: euv::ConsumeMode) {
+    }
+
+    fn borrow(&mut self,
+              _borrow_id: ast::NodeId,
+              _borrow_span: Span,
+              _cmt: mc::cmt,
+              _loan_region: ty::Region,
+              _bk: ty::BorrowKind,
+              _loan_cause: euv::LoanCause) {
+    }
+
+    fn decl_without_init(&mut self,
+                         _id: ast::NodeId,
+                         _span: Span) {
+    }
+
+    fn mutate(&mut self,
+              _assignment_id: ast::NodeId,
+              _assignment_span: Span,
+              _assignee_cmt: mc::cmt,
+              _mode: euv::MutateMode) {
+    }
+}

src/librustc/middle/mem_categorization.rs

@@ -150,7 +150,7 @@ pub enum MutabilityCategory {
 // like `*x`, the type of this deref node is the deref'd type (`T`),
 // but in a pattern like `@x`, the `@x` pattern is again a
 // dereference, but its type is the type *before* the dereference
-// (`@T`). So use `cmt.type` to find the type of the value in a consistent
+// (`@T`). So use `cmt.ty` to find the type of the value in a consistent
 // fashion. For more details, see the method `cat_pattern`
 #[deriving(Clone, PartialEq)]
 pub struct cmt_ {

src/test/compile-fail/dst-bad-assign-2.rs

@@ -43,4 +43,5 @@ pub fn main() {
     let f5: &mut Fat<ToBar> = &mut Fat { f1: 5, f2: "some str", ptr: Bar1 {f :42} };
     let z: Box<ToBar> = box Bar1 {f: 36};
     f5.ptr = *z;  //~ ERROR dynamically sized type on lhs of assignment
+    //~^ ERROR E0161
 }

src/test/compile-fail/dst-bad-deep.rs

@@ -22,4 +22,5 @@ pub fn main() {
     let g: &Fat<[int]> = &f;
     let h: &Fat<Fat<[int]>> = &Fat { ptr: *g };
     //~^ ERROR trying to initialise a dynamically sized struct
+    //~^^ ERROR E0161
 }

src/test/compile-fail/dst-rvalue.rs

@@ -0,0 +1,20 @@
+// 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 dynamically sized rvalues are forbidden
+
+pub fn main() {
+    let _x: Box<str> = box *"hello world";
+    //~^ ERROR E0161
+
+    let array: &[int] = &[1, 2, 3];
+    let _x: Box<[int]> = box *array;
+    //~^ ERROR E0161
+}

src/test/compile-fail/issue-5883.rs

@@ -17,6 +17,8 @@ struct Struct {
 fn new_struct(r: A+'static) -> Struct {
     //~^ ERROR variable `r` has dynamically sized type
     Struct { r: r } //~ ERROR trying to initialise a dynamically sized struct
+    //~^ ERROR E0161
+    //~^^ ERROR E0161
 }
 
 trait Curve {}

src/test/compile-fail/unsized3.rs

@@ -51,8 +51,10 @@ fn f8<Sized? X>(x1: &S<X>, x2: &S<X>) {
 
 // Test some tuples.
 fn f9<Sized? X>(x1: Box<S<X>>, x2: Box<E<X>>) {
-    f5(&(*x1, 34i)); //~ERROR instantiating a type parameter with an incompatible type `(S<X>,int)`,
-    f5(&(32i, *x2)); //~ERROR instantiating a type parameter with an incompatible type `(int,E<X>)`,
+    f5(&(*x1, 34i)); //~ERROR E0161
+    //~^ ERROR instantiating a type parameter with an incompatible type
+    f5(&(32i, *x2)); //~ERROR E0161
+    //~^ ERROR instantiating a type parameter with an incompatible type
 }
 
 // I would like these to fail eventually.

src/test/compile-fail/unsized6.rs

@@ -30,11 +30,13 @@ fn f3<Sized? X>(x1: Box<X>, x2: Box<X>, x3: Box<X>) {
     let y: X = *x1; //~ERROR variable `y` has dynamically sized type `X`
     let y = *x2; //~ERROR variable `y` has dynamically sized type `X`
     let (y, z) = (*x3, 4i); //~ERROR variable `y` has dynamically sized type `X`
+    //~^ ERROR E0161
 }
 fn f4<Sized? X: T>(x1: Box<X>, x2: Box<X>, x3: Box<X>) {
     let y: X = *x1;         //~ERROR variable `y` has dynamically sized type `X`
     let y = *x2;            //~ERROR variable `y` has dynamically sized type `X`
     let (y, z) = (*x3, 4i); //~ERROR variable `y` has dynamically sized type `X`
+    //~^ ERROR E0161
 }
 
 fn g1<Sized? X>(x: X) {} //~ERROR variable `x` has dynamically sized type `X`