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auto merge of #11979 : FlaPer87/rust/static, r=nikomatsakis
This pull request partially addresses the 2 issues listed before. As part of the work required for this PR, `NonCopyable` was completely removed. This PR also replaces the content of `type_is_pod` with `TypeContents::is_pod`, although `type_is_content` is currently not being used anywhere. I kept it for consistency with the other functions that exist in this module. cc #10834 cc #10577 Proposed static restrictions ===================== Taken from [this](#11979 (comment)) comment. I expect some code that, at a high-level, works like this: - For each *mutable* static item, check that the **type**: - cannot own any value whose type has a dtor - cannot own any values whose type is an owned pointer - For each *immutable* static item, check that the **value**: - does not contain any ~ or box expressions (including ~[1, 2, 3] sort of things, for now) - does not contain a struct literal or call to an enum variant / struct constructor where - the type of the struct/enum is freeze - the type of the struct/enum has a dtor
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,159 @@ | ||
| // 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. | ||
|
|
||
| // Verifies that the types and values of static items | ||
| // are safe. The rules enforced by this module are: | ||
| // | ||
| // - For each *mutable* static item, it checks that its **type**: | ||
| // - doesn't have a destructor | ||
| // - doesn't own an owned pointer | ||
| // | ||
| // - For each *immutable* static item, it checks that its **value**: | ||
| // - doesn't own owned, managed pointers | ||
| // - doesn't contain a struct literal or a call to an enum variant / struct constructor where | ||
| // - the type of the struct/enum is not freeze | ||
| // - the type of the struct/enum has a dtor | ||
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|
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| use middle::ty; | ||
|
|
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| use syntax::ast; | ||
| use syntax::codemap::Span; | ||
| use syntax::visit::Visitor; | ||
| use syntax::visit; | ||
| use syntax::print::pprust; | ||
|
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| fn safe_type_for_static_mut(cx: ty::ctxt, e: &ast::Expr) -> Option<~str> { | ||
| let node_ty = ty::node_id_to_type(cx, e.id); | ||
| let tcontents = ty::type_contents(cx, node_ty); | ||
| debug!("safe_type_for_static_mut(dtor={}, managed={}, owned={})", | ||
| tcontents.has_dtor(), tcontents.owns_managed(), tcontents.owns_owned()) | ||
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| let suffix = if tcontents.has_dtor() { | ||
| "destructors" | ||
| } else if tcontents.owns_managed() { | ||
| "managed pointers" | ||
| } else if tcontents.owns_owned() { | ||
| "owned pointers" | ||
| } else { | ||
| return None; | ||
| }; | ||
|
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| Some(format!("mutable static items are not allowed to have {}", suffix)) | ||
| } | ||
|
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| struct CheckStaticVisitor { | ||
| tcx: ty::ctxt, | ||
| } | ||
|
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| pub fn check_crate(tcx: ty::ctxt, krate: &ast::Crate) { | ||
| visit::walk_crate(&mut CheckStaticVisitor { tcx: tcx }, krate, false) | ||
| } | ||
|
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| impl CheckStaticVisitor { | ||
|
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| fn report_error(&self, span: Span, result: Option<~str>) -> bool { | ||
| match result { | ||
| None => { false } | ||
| Some(msg) => { | ||
| self.tcx.sess.span_err(span, msg); | ||
| true | ||
| } | ||
| } | ||
| } | ||
| } | ||
|
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| impl Visitor<bool> for CheckStaticVisitor { | ||
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| fn visit_item(&mut self, i: &ast::Item, _is_const: bool) { | ||
| debug!("visit_item(item={})", pprust::item_to_str(i)); | ||
| match i.node { | ||
| ast::ItemStatic(_, mutability, expr) => { | ||
| match mutability { | ||
| ast::MutImmutable => { | ||
| self.visit_expr(expr, true); | ||
| } | ||
| ast::MutMutable => { | ||
| self.report_error(expr.span, safe_type_for_static_mut(self.tcx, expr)); | ||
| } | ||
| } | ||
| } | ||
| _ => { visit::walk_item(self, i, false) } | ||
| } | ||
| } | ||
|
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| /// This method is used to enforce the constraints on | ||
| /// immutable static items. It walks through the *value* | ||
| /// of the item walking down the expression and evaluating | ||
| /// every nested expression. if the expression is not part | ||
| /// of a static item, this method does nothing but walking | ||
| /// down through it. | ||
| fn visit_expr(&mut self, e: &ast::Expr, is_const: bool) { | ||
| debug!("visit_expr(expr={})", pprust::expr_to_str(e)); | ||
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| if !is_const { | ||
| return visit::walk_expr(self, e, is_const); | ||
| } | ||
|
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| match e.node { | ||
| ast::ExprField(..) | ast::ExprVec(..) | | ||
| ast::ExprBlock(..) | ast::ExprTup(..) | | ||
| ast::ExprVstore(_, ast::ExprVstoreSlice) => { | ||
| visit::walk_expr(self, e, is_const); | ||
| } | ||
| ast::ExprUnary(ast::UnBox, _) => { | ||
| self.tcx.sess.span_err(e.span, | ||
| "static items are not allowed to have managed pointers"); | ||
| } | ||
| ast::ExprBox(..) | | ||
| ast::ExprUnary(ast::UnUniq, _) | | ||
| ast::ExprVstore(_, ast::ExprVstoreUniq) => { | ||
| self.tcx.sess.span_err(e.span, | ||
| "static items are not allowed to have owned pointers"); | ||
| } | ||
| ast::ExprProc(..) => { | ||
| self.report_error(e.span, | ||
| Some(~"immutable static items must be `Freeze`")); | ||
| return; | ||
| } | ||
| ast::ExprAddrOf(mutability, _) => { | ||
| match mutability { | ||
| ast::MutMutable => { | ||
| self.report_error(e.span, | ||
| Some(~"immutable static items must be `Freeze`")); | ||
| return; | ||
| } | ||
| _ => {} | ||
| } | ||
| } | ||
| _ => { | ||
| let node_ty = ty::node_id_to_type(self.tcx, e.id); | ||
|
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| match ty::get(node_ty).sty { | ||
| ty::ty_struct(did, _) | | ||
| ty::ty_enum(did, _) => { | ||
| if ty::has_dtor(self.tcx, did) { | ||
| self.report_error(e.span, | ||
| Some(~"static items are not allowed to have destructors")); | ||
| return; | ||
| } | ||
| if Some(did) == self.tcx.lang_items.no_freeze_bound() { | ||
| self.report_error(e.span, | ||
| Some(~"immutable static items must be `Freeze`")); | ||
| return; | ||
| } | ||
| } | ||
| _ => {} | ||
| } | ||
| visit::walk_expr(self, e, is_const); | ||
| } | ||
| } | ||
| } | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,29 @@ | ||
| // 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. | ||
|
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| // Ensure that moves out of static items is forbidden | ||
|
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| use std::kinds::marker; | ||
|
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| struct Foo { | ||
| foo: int, | ||
| nopod: marker::NoPod | ||
| } | ||
|
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| static BAR: Foo = Foo{foo: 5, nopod: marker::NoPod}; | ||
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| fn test(f: Foo) { | ||
| let _f = Foo{foo: 4, ..f}; | ||
| } | ||
|
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| fn main() { | ||
| test(BAR); //~ ERROR cannot move out of static item | ||
| } |
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