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stop using MatchCheckCtxt to hold the param-env for check_match

This commit is contained in:
Ariel Ben-Yehuda 2016-09-30 00:37:19 +03:00
parent e313d8b290
commit 37418b850f
2 changed files with 160 additions and 134 deletions
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18
src/librustc_const_eval/_match.rs
View File

@ -155,7 +155,6 @@ impl<'a, 'tcx> FromIterator<Vec<&'a Pattern<'tcx>>> for Matrix<'a, 'tcx> {
//NOTE: appears to be the only place other then InferCtxt to contain a ParamEnv
pub struct MatchCheckCtxt<'a, 'tcx: 'a> {
pub tcx: TyCtxt<'a, 'tcx, 'tcx>,
pub param_env: ty::ParameterEnvironment<'tcx>,
/// A wild pattern with an error type - it exists to avoid having to normalize
/// associated types to get field types.
pub wild_pattern: &'a Pattern<'tcx>,
@ -165,7 +164,6 @@ pub struct MatchCheckCtxt<'a, 'tcx: 'a> {
impl<'a, 'tcx> MatchCheckCtxt<'a, 'tcx> {
pub fn create_and_enter<F, R>(
tcx: TyCtxt<'a, 'tcx, 'tcx>,
param_env: ty::ParameterEnvironment<'tcx>,
f: F) -> R
where F: for<'b> FnOnce(MatchCheckCtxt<'b, 'tcx>) -> R
{
@ -179,7 +177,6 @@ impl<'a, 'tcx> MatchCheckCtxt<'a, 'tcx> {
f(MatchCheckCtxt {
tcx: tcx,
param_env: param_env,
wild_pattern: &wild_pattern,
pattern_arena: &pattern_arena,
})
@ -675,18 +672,3 @@ fn specialize<'a, 'tcx>(
head
})
}
pub fn is_refutable<'a, 'tcx, A, F>(
cx: &MatchCheckCtxt<'a, 'tcx>,
pat: &'a Pattern<'tcx>,
refutable: F)
-> Option<A> where
F: FnOnce(&Witness) -> A,
{
let pats = Matrix(vec![vec![pat]]);
match is_useful(cx, &pats, &[cx.wild_pattern], ConstructWitness) {
UsefulWithWitness(pats) => Some(refutable(&pats[0])),
NotUseful => None,
Useful => bug!()
}
}

276
src/librustc_const_eval/check_match.rs
View File

@ -8,7 +8,7 @@
// option. This file may not be copied, modified, or distributed
// except according to those terms.
use _match::{MatchCheckCtxt, Matrix, lower_pat, is_refutable, is_useful};
use _match::{MatchCheckCtxt, Matrix, lower_pat, is_useful};
use _match::{DUMMY_WILD_PAT};
use _match::Usefulness::*;
use _match::WitnessPreference::*;
@ -44,23 +44,47 @@ use syntax::ptr::P;
use syntax::util::move_map::MoveMap;
use syntax_pos::Span;
impl<'a, 'tcx, 'v> Visitor<'v> for MatchCheckCtxt<'a, 'tcx> {
fn visit_expr(&mut self, ex: &hir::Expr) {
check_expr(self, ex);
struct OuterVisitor<'a, 'tcx: 'a> { tcx: TyCtxt<'a, 'tcx, 'tcx> }
impl<'a, 'v, 'tcx> Visitor<'v> for OuterVisitor<'a, 'tcx> {
fn visit_expr(&mut self, _expr: &hir::Expr) {
return // const, static and N in [T; N] - shouldn't contain anything
}
fn visit_local(&mut self, l: &hir::Local) {
check_local(self, l);
fn visit_trait_item(&mut self, item: &hir::TraitItem) {
if let hir::ConstTraitItem(..) = item.node {
return // nothing worth match checking in a constant
} else {
intravisit::walk_trait_item(self, item);
}
}
fn visit_impl_item(&mut self, item: &hir::ImplItem) {
if let hir::ImplItemKind::Const(..) = item.node {
return // nothing worth match checking in a constant
} else {
intravisit::walk_impl_item(self, item);
}
}
fn visit_fn(&mut self, fk: FnKind<'v>, fd: &'v hir::FnDecl,
b: &'v hir::Block, s: Span, n: ast::NodeId) {
check_fn(self, fk, fd, b, s, n);
b: &'v hir::Block, s: Span, id: ast::NodeId) {
if let FnKind::Closure(..) = fk {
span_bug!(s, "check_match: closure outside of function")
}
MatchVisitor {
tcx: self.tcx,
param_env: &ty::ParameterEnvironment::for_item(self.tcx, id)
}.visit_fn(fk, fd, b, s, id);
}
}
impl<'a, 'tcx> OuterVisitor<'a, 'tcx> {
}
pub fn check_crate<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>) {
MatchCheckCtxt::create_and_enter(tcx, tcx.empty_parameter_environment(), |mut cx| {
tcx.visit_all_items_in_krate(DepNode::MatchCheck, &mut cx);
});
tcx.visit_all_items_in_krate(DepNode::MatchCheck, &mut OuterVisitor { tcx: tcx });
tcx.sess.abort_if_errors();
}
@ -68,65 +92,108 @@ fn create_e0004<'a>(sess: &'a Session, sp: Span, error_message: String) -> Diagn
struct_span_err!(sess, sp, E0004, "{}", &error_message)
}
fn check_expr(cx: &mut MatchCheckCtxt, ex: &hir::Expr) {
intravisit::walk_expr(cx, ex);
match ex.node {
hir::ExprMatch(ref scrut, ref arms, source) => {
for arm in arms {
// First, check legality of move bindings.
check_legality_of_move_bindings(cx,
arm.guard.is_some(),
&arm.pats);
struct MatchVisitor<'a, 'tcx: 'a> {
tcx: TyCtxt<'a, 'tcx, 'tcx>,
param_env: &'a ty::ParameterEnvironment<'tcx>
}
// Second, if there is a guard on each arm, make sure it isn't
// assigning or borrowing anything mutably.
if let Some(ref guard) = arm.guard {
check_for_mutation_in_guard(cx, &guard);
}
impl<'a, 'tcx, 'v> Visitor<'v> for MatchVisitor<'a, 'tcx> {
fn visit_expr(&mut self, ex: &hir::Expr) {
intravisit::walk_expr(self, ex);
match ex.node {
hir::ExprMatch(ref scrut, ref arms, source) => {
self.check_match(scrut, arms, source, ex.span);
}
_ => {}
}
}
let mut static_inliner = StaticInliner::new(cx.tcx);
let inlined_arms = arms.iter().map(|arm| {
(arm.pats.iter().map(|pat| {
static_inliner.fold_pat((*pat).clone())
}).collect(), arm.guard.as_ref().map(|e| &**e))
}).collect::<Vec<(Vec<P<Pat>>, Option<&hir::Expr>)>>();
fn visit_local(&mut self, loc: &hir::Local) {
intravisit::walk_local(self, loc);
// Bail out early if inlining failed.
if static_inliner.failed {
return;
let pat = StaticInliner::new(self.tcx).fold_pat(loc.pat.clone());
self.check_irrefutable(&pat, false);
// Check legality of move bindings and `@` patterns.
self.check_patterns(false, slice::ref_slice(&loc.pat));
}
fn visit_fn(&mut self, fk: FnKind<'v>, fd: &'v hir::FnDecl,
b: &'v hir::Block, s: Span, n: ast::NodeId) {
intravisit::walk_fn(self, fk, fd, b, s, n);
for input in &fd.inputs {
self.check_irrefutable(&input.pat, true);
self.check_patterns(false, slice::ref_slice(&input.pat));
}
}
}
impl<'a, 'tcx> MatchVisitor<'a, 'tcx> {
fn check_patterns(&self, has_guard: bool, pats: &[P<Pat>]) {
check_legality_of_move_bindings(self, has_guard, pats);
for pat in pats {
check_legality_of_bindings_in_at_patterns(self, pat);
}
}
fn check_match(
&self,
scrut: &hir::Expr,
arms: &[hir::Arm],
source: hir::MatchSource,
span: Span)
{
for arm in arms {
// First, check legality of move bindings.
self.check_patterns(arm.guard.is_some(), &arm.pats);
// Second, if there is a guard on each arm, make sure it isn't
// assigning or borrowing anything mutably.
if let Some(ref guard) = arm.guard {
check_for_mutation_in_guard(self, &guard);
}
}
for pat in inlined_arms
.iter()
.flat_map(|&(ref pats, _)| pats) {
// Third, check legality of move bindings.
check_legality_of_bindings_in_at_patterns(cx, &pat);
let mut static_inliner = StaticInliner::new(self.tcx);
let inlined_arms = arms.iter().map(|arm| {
(arm.pats.iter().map(|pat| {
static_inliner.fold_pat((*pat).clone())
}).collect(), arm.guard.as_ref().map(|e| &**e))
}).collect::<Vec<(Vec<P<Pat>>, Option<&hir::Expr>)>>();
// Fourth, check if there are any references to NaN that we should warn about.
check_for_static_nan(cx, &pat);
// Bail out early if inlining failed.
if static_inliner.failed {
return;
}
// Fifth, check if for any of the patterns that match an enumerated type
// are bindings with the same name as one of the variants of said type.
check_for_bindings_named_the_same_as_variants(cx, &pat);
}
for pat in inlined_arms.iter().flat_map(|&(ref pats, _)| pats) {
// Fourth, check if there are any references to NaN that we should warn about.
check_for_static_nan(self, &pat);
// Fifth, check if for any of the patterns that match an enumerated type
// are bindings with the same name as one of the variants of said type.
check_for_bindings_named_the_same_as_variants(self, &pat);
}
MatchCheckCtxt::create_and_enter(self.tcx, |ref cx| {
// Fourth, check for unreachable arms.
check_arms(cx, &inlined_arms[..], source);
// Finally, check if the whole match expression is exhaustive.
// Check for empty enum, because is_useful only works on inhabited types.
let pat_ty = cx.tcx.node_id_to_type(scrut.id);
let pat_ty = self.tcx.node_id_to_type(scrut.id);
if inlined_arms.is_empty() {
if !pat_ty.is_uninhabited(cx.tcx) {
if !pat_ty.is_uninhabited(self.tcx) {
// We know the type is inhabited, so this must be wrong
let mut err = create_e0004(cx.tcx.sess, ex.span,
let mut err = create_e0004(self.tcx.sess, span,
format!("non-exhaustive patterns: type {} \
is non-empty",
pat_ty));
span_help!(&mut err, ex.span,
"Please ensure that all possible cases are being handled; \
possibly adding wildcards or more match arms.");
span_help!(&mut err, span,
"Please ensure that all possible cases are being handled; \
possibly adding wildcards or more match arms.");
err.emit();
}
// If the type *is* uninhabited, it's vacuously exhaustive
@ -140,12 +207,40 @@ fn check_expr(cx: &mut MatchCheckCtxt, ex: &hir::Expr) {
.map(|pat| vec![lower_pat(cx, &pat)])
.collect();
check_exhaustive(cx, scrut.span, &matrix, source);
},
_ => ()
})
}
fn check_irrefutable(&self, pat: &Pat, is_fn_arg: bool) {
let origin = if is_fn_arg {
"function argument"
} else {
"local binding"
};
MatchCheckCtxt::create_and_enter(self.tcx, |ref cx| {
let pats : Matrix = vec![vec![
lower_pat(cx, pat)
]].into_iter().collect();
let witness = match is_useful(cx, &pats, &[cx.wild_pattern], ConstructWitness) {
UsefulWithWitness(witness) => witness,
NotUseful => return,
Useful => bug!()
};
let pattern_string = pat_to_string(witness[0].single_pattern());
let mut diag = struct_span_err!(
self.tcx.sess, pat.span, E0005,
"refutable pattern in {}: `{}` not covered",
origin, pattern_string
);
diag.span_label(pat.span, &format!("pattern `{}` not covered", pattern_string));
diag.emit();
});
}
}
fn check_for_bindings_named_the_same_as_variants(cx: &MatchCheckCtxt, pat: &Pat) {
fn check_for_bindings_named_the_same_as_variants(cx: &MatchVisitor, pat: &Pat) {
pat.walk(|p| {
if let PatKind::Binding(hir::BindByValue(hir::MutImmutable), name, None) = p.node {
let pat_ty = cx.tcx.pat_ty(p);
@ -175,7 +270,7 @@ fn check_for_bindings_named_the_same_as_variants(cx: &MatchCheckCtxt, pat: &Pat)
}
// Check that we do not match against a static NaN (#6804)
fn check_for_static_nan(cx: &MatchCheckCtxt, pat: &Pat) {
fn check_for_static_nan(cx: &MatchVisitor, pat: &Pat) {
pat.walk(|p| {
if let PatKind::Lit(ref expr) = p.node {
match eval_const_expr_partial(cx.tcx, &expr, ExprTypeChecked, None) {
@ -444,56 +539,8 @@ impl<'a, 'tcx> StaticInliner<'a, 'tcx> {
}
}
fn check_local(cx: &mut MatchCheckCtxt, loc: &hir::Local) {
intravisit::walk_local(cx, loc);
let pat = StaticInliner::new(cx.tcx).fold_pat(loc.pat.clone());
check_irrefutable(cx, &pat, false);
// Check legality of move bindings and `@` patterns.
check_legality_of_move_bindings(cx, false, slice::ref_slice(&loc.pat));
check_legality_of_bindings_in_at_patterns(cx, &loc.pat);
}
fn check_fn(cx: &mut MatchCheckCtxt,
kind: FnKind,
decl: &hir::FnDecl,
body: &hir::Block,
sp: Span,
fn_id: ast::NodeId) {
match kind {
FnKind::Closure(_) => {}
_ => cx.param_env = ty::ParameterEnvironment::for_item(cx.tcx, fn_id),
}
intravisit::walk_fn(cx, kind, decl, body, sp, fn_id);
for input in &decl.inputs {
check_irrefutable(cx, &input.pat, true);
check_legality_of_move_bindings(cx, false, slice::ref_slice(&input.pat));
check_legality_of_bindings_in_at_patterns(cx, &input.pat);
}
}
fn check_irrefutable(cx: &MatchCheckCtxt, pat: &Pat, is_fn_arg: bool) {
let origin = if is_fn_arg {
"function argument"
} else {
"local binding"
};
is_refutable(cx, &lower_pat(cx, pat), |uncovered_pat| {
let pattern_string = pat_to_string(uncovered_pat.single_pattern());
struct_span_err!(cx.tcx.sess, pat.span, E0005,
"refutable pattern in {}: `{}` not covered",
origin,
pattern_string,
).span_label(pat.span, &format!("pattern `{}` not covered", pattern_string)).emit();
});
}
// Legality of move bindings checking
fn check_legality_of_move_bindings(cx: &MatchCheckCtxt,
fn check_legality_of_move_bindings(cx: &MatchVisitor,
has_guard: bool,
pats: &[P<Pat>]) {
let mut by_ref_span = None;
@ -532,13 +579,9 @@ fn check_legality_of_move_bindings(cx: &MatchCheckCtxt,
pat.walk(|p| {
if let PatKind::Binding(hir::BindByValue(..), _, ref sub) = p.node {
let pat_ty = cx.tcx.node_id_to_type(p.id);
//FIXME: (@jroesch) this code should be floated up as well
cx.tcx.infer_ctxt(None, Some(cx.param_env.clone()),
Reveal::NotSpecializable).enter(|infcx| {
if infcx.type_moves_by_default(pat_ty, pat.span) {
check_move(p, sub.as_ref().map(|p| &**p));
}
});
if pat_ty.moves_by_default(cx.tcx, cx.param_env, pat.span) {
check_move(p, sub.as_ref().map(|p| &**p));
}
}
true
});
@ -547,8 +590,9 @@ fn check_legality_of_move_bindings(cx: &MatchCheckCtxt,
/// Ensures that a pattern guard doesn't borrow by mutable reference or
/// assign.
fn check_for_mutation_in_guard<'a, 'tcx>(cx: &'a MatchCheckCtxt<'a, 'tcx>,
guard: &hir::Expr) {
///
/// FIXME: this should be done by borrowck.
fn check_for_mutation_in_guard(cx: &MatchVisitor, guard: &hir::Expr) {
cx.tcx.infer_ctxt(None, Some(cx.param_env.clone()),
Reveal::NotSpecializable).enter(|infcx| {
let mut checker = MutationChecker {
@ -560,7 +604,7 @@ fn check_for_mutation_in_guard<'a, 'tcx>(cx: &'a MatchCheckCtxt<'a, 'tcx>,
}
struct MutationChecker<'a, 'gcx: 'a> {
cx: &'a MatchCheckCtxt<'a, 'gcx>,
cx: &'a MatchVisitor<'a, 'gcx>,
}
impl<'a, 'gcx, 'tcx> Delegate<'tcx> for MutationChecker<'a, 'gcx> {
@ -600,12 +644,12 @@ impl<'a, 'gcx, 'tcx> Delegate<'tcx> for MutationChecker<'a, 'gcx> {
/// Forbids bindings in `@` patterns. This is necessary for memory safety,
/// because of the way rvalues are handled in the borrow check. (See issue
/// #14587.)
fn check_legality_of_bindings_in_at_patterns(cx: &MatchCheckCtxt, pat: &Pat) {
fn check_legality_of_bindings_in_at_patterns(cx: &MatchVisitor, pat: &Pat) {
AtBindingPatternVisitor { cx: cx, bindings_allowed: true }.visit_pat(pat);
}
struct AtBindingPatternVisitor<'a, 'b:'a, 'tcx:'b> {
cx: &'a MatchCheckCtxt<'b, 'tcx>,
cx: &'a MatchVisitor<'b, 'tcx>,
bindings_allowed: bool
}