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Make expr_is_lval more robust

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Previously it also tried to find out the best way to translate the
expression, which could ICE during type-checking.

Fixes #23173
Fixes #24322
Fixes #25757
This commit is contained in:
Ariel Ben-Yehuda 2015-06-21 22:29:13 +03:00
parent a38e7585fc
commit 59be753544
5 changed files with 256 additions and 140 deletions
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157
src/librustc/middle/ty.rs
View File

@ -20,7 +20,6 @@ pub use self::Variance::*;
pub use self::AutoAdjustment::*;
pub use self::Representability::*;
pub use self::AutoRef::*;
pub use self::ExprKind::*;
pub use self::DtorKind::*;
pub use self::ExplicitSelfCategory::*;
pub use self::FnOutput::*;
@ -87,7 +86,7 @@ use syntax::abi;
use syntax::ast::{CrateNum, DefId, ItemImpl, ItemTrait, LOCAL_CRATE};
use syntax::ast::{MutImmutable, MutMutable, Name, NamedField, NodeId};
use syntax::ast::{StmtExpr, StmtSemi, StructField, UnnamedField, Visibility};
use syntax::ast_util::{self, is_local, lit_is_str, local_def};
use syntax::ast_util::{self, is_local, local_def};
use syntax::attr::{self, AttrMetaMethods, SignedInt, UnsignedInt};
use syntax::codemap::Span;
use syntax::parse::token::{self, InternedString, special_idents};
@ -5106,96 +5105,27 @@ pub fn resolve_expr(tcx: &ctxt, expr: &ast::Expr) -> def::Def {
}
}
pub fn expr_is_lval(tcx: &ctxt, e: &ast::Expr) -> bool {
match expr_kind(tcx, e) {
LvalueExpr => true,
RvalueDpsExpr | RvalueDatumExpr | RvalueStmtExpr => false
}
}
/// We categorize expressions into three kinds. The distinction between
/// lvalue/rvalue is fundamental to the language. The distinction between the
/// two kinds of rvalues is an artifact of trans which reflects how we will
/// generate code for that kind of expression. See trans/expr.rs for more
/// information.
#[derive(Copy, Clone)]
pub enum ExprKind {
LvalueExpr,
RvalueDpsExpr,
RvalueDatumExpr,
RvalueStmtExpr
}
pub fn expr_kind(tcx: &ctxt, expr: &ast::Expr) -> ExprKind {
if tcx.method_map.borrow().contains_key(&MethodCall::expr(expr.id)) {
// Overloaded operations are generally calls, and hence they are
// generated via DPS, but there are a few exceptions:
return match expr.node {
// `a += b` has a unit result.
ast::ExprAssignOp(..) => RvalueStmtExpr,
// the deref method invoked for `*a` always yields an `&T`
ast::ExprUnary(ast::UnDeref, _) => LvalueExpr,
// the index method invoked for `a[i]` always yields an `&T`
ast::ExprIndex(..) => LvalueExpr,
// in the general case, result could be any type, use DPS
_ => RvalueDpsExpr
};
}
match expr.node {
pub fn expr_is_lval(tcx: &ctxt, expr: &ast::Expr) -> bool {
match expr.node {
ast::ExprPath(..) => {
match resolve_expr(tcx, expr) {
def::DefVariant(tid, vid, _) => {
let variant_info = enum_variant_with_id(tcx, tid, vid);
if !variant_info.args.is_empty() {
// N-ary variant.
RvalueDatumExpr
} else {
// Nullary variant.
RvalueDpsExpr
}
// We can't use resolve_expr here, as this needs to run on broken
// programs. We don't need to through - associated items are all
// rvalues.
match tcx.def_map.borrow().get(&expr.id) {
Some(&def::PathResolution {
base_def: def::DefStatic(..), ..
}) | Some(&def::PathResolution {
base_def: def::DefUpvar(..), ..
}) | Some(&def::PathResolution {
base_def: def::DefLocal(..), ..
}) => {
true
}
def::DefStruct(_) => {
match tcx.node_types.borrow().get(&expr.id) {
Some(ty) => match ty.sty {
TyBareFn(..) => RvalueDatumExpr,
_ => RvalueDpsExpr
},
// See ExprCast below for why types might be missing.
None => RvalueDatumExpr
}
}
Some(..) => false,
// Special case: A unit like struct's constructor must be called without () at the
// end (like `UnitStruct`) which means this is an ExprPath to a DefFn. But in case
// of unit structs this is should not be interpreted as function pointer but as
// call to the constructor.
def::DefFn(_, true) => RvalueDpsExpr,
// Fn pointers are just scalar values.
def::DefFn(..) | def::DefMethod(..) => RvalueDatumExpr,
// Note: there is actually a good case to be made that
// DefArg's, particularly those of immediate type, ought to
// considered rvalues.
def::DefStatic(..) |
def::DefUpvar(..) |
def::DefLocal(..) => LvalueExpr,
def::DefConst(..) |
def::DefAssociatedConst(..) => RvalueDatumExpr,
def => {
tcx.sess.span_bug(
expr.span,
&format!("uncategorized def for expr {}: {:?}",
expr.id,
def));
}
None => tcx.sess.span_bug(expr.span, &format!(
"no def for path {}", expr.id))
}
}
@ -5203,7 +5133,7 @@ pub fn expr_kind(tcx: &ctxt, expr: &ast::Expr) -> ExprKind {
ast::ExprField(..) |
ast::ExprTupField(..) |
ast::ExprIndex(..) => {
LvalueExpr
true
}
ast::ExprCall(..) |
@ -5216,25 +5146,7 @@ pub fn expr_kind(tcx: &ctxt, expr: &ast::Expr) -> ExprKind {
ast::ExprClosure(..) |
ast::ExprBlock(..) |
ast::ExprRepeat(..) |
ast::ExprVec(..) => {
RvalueDpsExpr
}
ast::ExprIfLet(..) => {
tcx.sess.span_bug(expr.span, "non-desugared ExprIfLet");
}
ast::ExprWhileLet(..) => {
tcx.sess.span_bug(expr.span, "non-desugared ExprWhileLet");
}
ast::ExprForLoop(..) => {
tcx.sess.span_bug(expr.span, "non-desugared ExprForLoop");
}
ast::ExprLit(ref lit) if lit_is_str(&**lit) => {
RvalueDpsExpr
}
ast::ExprVec(..) |
ast::ExprBreak(..) |
ast::ExprAgain(..) |
ast::ExprRet(..) |
@ -5242,34 +5154,21 @@ pub fn expr_kind(tcx: &ctxt, expr: &ast::Expr) -> ExprKind {
ast::ExprLoop(..) |
ast::ExprAssign(..) |
ast::ExprInlineAsm(..) |
ast::ExprAssignOp(..) => {
RvalueStmtExpr
}
ast::ExprLit(_) | // Note: LitStr is carved out above
ast::ExprAssignOp(..) |
ast::ExprLit(_) |
ast::ExprUnary(..) |
ast::ExprBox(None, _) |
ast::ExprBox(..) |
ast::ExprAddrOf(..) |
ast::ExprBinary(..) |
ast::ExprCast(..) => {
RvalueDatumExpr
false
}
ast::ExprBox(Some(ref place), _) => {
// Special case `Box<T>` for now:
let def_id = match tcx.def_map.borrow().get(&place.id) {
Some(def) => def.def_id(),
None => panic!("no def for place"),
};
if tcx.lang_items.exchange_heap() == Some(def_id) {
RvalueDatumExpr
} else {
RvalueDpsExpr
}
}
ast::ExprParen(ref e) => expr_kind(tcx, &**e),
ast::ExprParen(ref e) => expr_is_lval(tcx, e),
ast::ExprIfLet(..) |
ast::ExprWhileLet(..) |
ast::ExprForLoop(..) |
ast::ExprMac(..) => {
tcx.sess.span_bug(
expr.span,

176
src/librustc_trans/trans/expr.rs
View File

@ -188,15 +188,15 @@ pub fn trans_into<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
false);
bcx.fcx.push_ast_cleanup_scope(cleanup_debug_loc);
let kind = ty::expr_kind(bcx.tcx(), expr);
let kind = expr_kind(bcx.tcx(), expr);
bcx = match kind {
ty::LvalueExpr | ty::RvalueDatumExpr => {
ExprKind::Lvalue | ExprKind::RvalueDatum => {
trans_unadjusted(bcx, expr).store_to_dest(dest, expr.id)
}
ty::RvalueDpsExpr => {
ExprKind::RvalueDps => {
trans_rvalue_dps_unadjusted(bcx, expr, dest)
}
ty::RvalueStmtExpr => {
ExprKind::RvalueStmt => {
trans_rvalue_stmt_unadjusted(bcx, expr)
}
};
@ -582,8 +582,8 @@ fn trans_unadjusted<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
debuginfo::set_source_location(bcx.fcx, expr.id, expr.span);
return match ty::expr_kind(bcx.tcx(), expr) {
ty::LvalueExpr | ty::RvalueDatumExpr => {
return match expr_kind(bcx.tcx(), expr) {
ExprKind::Lvalue | ExprKind::RvalueDatum => {
let datum = unpack_datum!(bcx, {
trans_datum_unadjusted(bcx, expr)
});
@ -591,12 +591,12 @@ fn trans_unadjusted<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
DatumBlock {bcx: bcx, datum: datum}
}
ty::RvalueStmtExpr => {
ExprKind::RvalueStmt => {
bcx = trans_rvalue_stmt_unadjusted(bcx, expr);
nil(bcx, expr_ty(bcx, expr))
}
ty::RvalueDpsExpr => {
ExprKind::RvalueDps => {
let ty = expr_ty(bcx, expr);
if type_is_zero_size(bcx.ccx(), ty) {
bcx = trans_rvalue_dps_unadjusted(bcx, expr, Ignore);
@ -1531,11 +1531,13 @@ pub fn trans_adt<'a, 'blk, 'tcx>(mut bcx: Block<'blk, 'tcx>,
// Second, trans the base to the dest.
assert_eq!(discr, 0);
match ty::expr_kind(bcx.tcx(), &*base.expr) {
ty::RvalueDpsExpr | ty::RvalueDatumExpr if !bcx.fcx.type_needs_drop(ty) => {
match expr_kind(bcx.tcx(), &*base.expr) {
ExprKind::RvalueDps | ExprKind::RvalueDatum if !bcx.fcx.type_needs_drop(ty) => {
bcx = trans_into(bcx, &*base.expr, SaveIn(addr));
},
ty::RvalueStmtExpr => bcx.tcx().sess.bug("unexpected expr kind for struct base expr"),
ExprKind::RvalueStmt => {
bcx.tcx().sess.bug("unexpected expr kind for struct base expr")
}
_ => {
let base_datum = unpack_datum!(bcx, trans_to_lvalue(bcx, &*base.expr, "base"));
for &(i, t) in &base.fields {
@ -2592,3 +2594,155 @@ fn with_overflow_check<'blk, 'tcx>(bcx: Block<'blk, 'tcx>, oop: OverflowOp, info
(bcx, res)
}
}
/// We categorize expressions into three kinds. The distinction between
/// lvalue/rvalue is fundamental to the language. The distinction between the
/// two kinds of rvalues is an artifact of trans which reflects how we will
/// generate code for that kind of expression. See trans/expr.rs for more
/// information.
#[derive(Copy, Clone)]
enum ExprKind {
Lvalue,
RvalueDps,
RvalueDatum,
RvalueStmt
}
fn expr_kind(tcx: &ty::ctxt, expr: &ast::Expr) -> ExprKind {
if tcx.method_map.borrow().contains_key(&MethodCall::expr(expr.id)) {
// Overloaded operations are generally calls, and hence they are
// generated via DPS, but there are a few exceptions:
return match expr.node {
// `a += b` has a unit result.
ast::ExprAssignOp(..) => ExprKind::RvalueStmt,
// the deref method invoked for `*a` always yields an `&T`
ast::ExprUnary(ast::UnDeref, _) => ExprKind::Lvalue,
// the index method invoked for `a[i]` always yields an `&T`
ast::ExprIndex(..) => ExprKind::Lvalue,
// in the general case, result could be any type, use DPS
_ => ExprKind::RvalueDps
};
}
match expr.node {
ast::ExprPath(..) => {
match ty::resolve_expr(tcx, expr) {
def::DefStruct(_) | def::DefVariant(..) => {
if let ty::TyBareFn(..) = ty::node_id_to_type(tcx, expr.id).sty {
// ctor function
ExprKind::RvalueDatum
} else {
ExprKind::RvalueDps
}
}
// Special case: A unit like struct's constructor must be called without () at the
// end (like `UnitStruct`) which means this is an ExprPath to a DefFn. But in case
// of unit structs this is should not be interpreted as function pointer but as
// call to the constructor.
def::DefFn(_, true) => ExprKind::RvalueDps,
// Fn pointers are just scalar values.
def::DefFn(..) | def::DefMethod(..) => ExprKind::RvalueDatum,
// Note: there is actually a good case to be made that
// DefArg's, particularly those of immediate type, ought to
// considered rvalues.
def::DefStatic(..) |
def::DefUpvar(..) |
def::DefLocal(..) => ExprKind::Lvalue,
def::DefConst(..) |
def::DefAssociatedConst(..) => ExprKind::RvalueDatum,
def => {
tcx.sess.span_bug(
expr.span,
&format!("uncategorized def for expr {}: {:?}",
expr.id,
def));
}
}
}
ast::ExprUnary(ast::UnDeref, _) |
ast::ExprField(..) |
ast::ExprTupField(..) |
ast::ExprIndex(..) => {
ExprKind::Lvalue
}
ast::ExprCall(..) |
ast::ExprMethodCall(..) |
ast::ExprStruct(..) |
ast::ExprRange(..) |
ast::ExprTup(..) |
ast::ExprIf(..) |
ast::ExprMatch(..) |
ast::ExprClosure(..) |
ast::ExprBlock(..) |
ast::ExprRepeat(..) |
ast::ExprVec(..) => {
ExprKind::RvalueDps
}
ast::ExprIfLet(..) => {
tcx.sess.span_bug(expr.span, "non-desugared ExprIfLet");
}
ast::ExprWhileLet(..) => {
tcx.sess.span_bug(expr.span, "non-desugared ExprWhileLet");
}
ast::ExprForLoop(..) => {
tcx.sess.span_bug(expr.span, "non-desugared ExprForLoop");
}
ast::ExprLit(ref lit) if ast_util::lit_is_str(&**lit) => {
ExprKind::RvalueDps
}
ast::ExprBreak(..) |
ast::ExprAgain(..) |
ast::ExprRet(..) |
ast::ExprWhile(..) |
ast::ExprLoop(..) |
ast::ExprAssign(..) |
ast::ExprInlineAsm(..) |
ast::ExprAssignOp(..) => {
ExprKind::RvalueStmt
}
ast::ExprLit(_) | // Note: LitStr is carved out above
ast::ExprUnary(..) |
ast::ExprBox(None, _) |
ast::ExprAddrOf(..) |
ast::ExprBinary(..) |
ast::ExprCast(..) => {
ExprKind::RvalueDatum
}
ast::ExprBox(Some(ref place), _) => {
// Special case `Box<T>` for now:
let def_id = match tcx.def_map.borrow().get(&place.id) {
Some(def) => def.def_id(),
None => panic!("no def for place"),
};
if tcx.lang_items.exchange_heap() == Some(def_id) {
ExprKind::RvalueDatum
} else {
ExprKind::RvalueDps
}
}
ast::ExprParen(ref e) => expr_kind(tcx, &**e),
ast::ExprMac(..) => {
tcx.sess.span_bug(
expr.span,
"macro expression remains after expansion");
}
}
}

17
src/test/compile-fail/issue-23173.rs Normal file
View File

@ -0,0 +1,17 @@
// Copyright 2015 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.
enum Token { LeftParen, RightParen, Plus, Minus, /* etc */ }
fn use_token(token: &Token) { unimplemented!() }
fn main() {
use_token(&Token::Homura); //~ ERROR no associated item named
}

19
src/test/compile-fail/issue-24322.rs Normal file
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@ -0,0 +1,19 @@
// Copyright 2015 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.
struct B;
impl B {
fn func(&self) -> u32 { 42 }
}
fn main() {
let x: &fn(&B) -> u32 = &B::func; //~ ERROR mismatched types
}

27
src/test/run-pass/issue-25757.rs Normal file
View File

@ -0,0 +1,27 @@
// Copyright 2015 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.
struct Foo {
a: u32
}
impl Foo {
fn x(&mut self) {
self.a = 5;
}
}
const FUNC: &'static Fn(&mut Foo) -> () = &Foo::x;
fn main() {
let mut foo = Foo { a: 137 };
FUNC(&mut foo); //~ ERROR bad
assert_eq!(foo.a, 5);
}