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Reason about nested free variables that appear in a function

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signature.  In a nutshell, the idea is to (1) report an error if, for
a region pointer `'a T`, the lifetime `'a` is longer than any
lifetimes that appear in `T` (in other words, if a borrowed pointer
outlives any portion of its contents) and then (2) use this to assume
that in a function like `fn(self: &'a &'b T)`, the relationship `'a <=
'b` holds. This is needed for #5656.  Fixes #5728.
This commit is contained in:
Niko Matsakis 2013-04-01 22:32:37 -07:00
parent 5606fc0c90
commit 3322595e89
27 changed files with 1027 additions and 347 deletions
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39
src/librustc/util/ppaux.rs
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@ -41,9 +41,9 @@ pub trait Repr {
}
pub fn note_and_explain_region(cx: ctxt,
prefix: ~str,
prefix: &str,
region: ty::Region,
suffix: ~str) {
suffix: &str) {
match explain_region_and_span(cx, region) {
(ref str, Some(span)) => {
cx.sess.span_note(
@ -98,23 +98,23 @@ pub fn explain_region_and_span(cx: ctxt, region: ty::Region)
}
}
re_free(id, br) => {
let prefix = match br {
re_free(ref fr) => {
let prefix = match fr.bound_region {
br_anon(idx) => fmt!("the anonymous lifetime #%u defined on",
idx + 1),
br_fresh(_) => fmt!("an anonymous lifetime defined on"),
_ => fmt!("the lifetime %s as defined on",
bound_region_to_str(cx, br))
bound_region_to_str(cx, fr.bound_region))
};
match cx.items.find(&id) {
match cx.items.find(&fr.scope_id) {
Some(&ast_map::node_block(ref blk)) => {
let (msg, opt_span) = explain_span(cx, "block", blk.span);
(fmt!("%s %s", prefix, msg), opt_span)
}
Some(_) | None => {
// this really should not happen
(fmt!("%s node %d", prefix, id), None)
(fmt!("%s node %d", prefix, fr.scope_id), None)
}
}
}
@ -215,7 +215,7 @@ pub fn region_to_str_space(cx: ctxt, prefix: &str, region: Region) -> ~str {
match region {
re_scope(_) => prefix.to_str(),
re_bound(br) => bound_region_to_str_space(cx, prefix, br),
re_free(_, br) => bound_region_to_str_space(cx, prefix, br),
re_free(ref fr) => bound_region_to_str_space(cx, prefix, fr.bound_region),
re_infer(ReSkolemized(_, br)) => {
bound_region_to_str_space(cx, prefix, br)
}
@ -225,12 +225,16 @@ pub fn region_to_str_space(cx: ctxt, prefix: &str, region: Region) -> ~str {
}
pub fn mt_to_str(cx: ctxt, m: &mt) -> ~str {
mt_to_str_wrapped(cx, "", m, "")
}
pub fn mt_to_str_wrapped(cx: ctxt, before: &str, m: &mt, after: &str) -> ~str {
let mstr = match m.mutbl {
ast::m_mutbl => "mut ",
ast::m_imm => "",
ast::m_const => "const "
};
return fmt!("%s%s", mstr, ty_to_str(cx, m.ty));
return fmt!("%s%s%s%s", mstr, before, ty_to_str(cx, m.ty), after);
}
pub fn vstore_to_str(cx: ctxt, vs: ty::vstore) -> ~str {
@ -250,15 +254,14 @@ pub fn trait_store_to_str(cx: ctxt, s: ty::TraitStore) -> ~str {
}
}
pub fn vstore_ty_to_str(cx: ctxt, ty: ~str, vs: ty::vstore) -> ~str {
pub fn vstore_ty_to_str(cx: ctxt, mt: &mt, vs: ty::vstore) -> ~str {
match vs {
ty::vstore_fixed(_) => {
fmt!("[%s, .. %s]", ty, vstore_to_str(cx, vs))
}
ty::vstore_slice(_) => {
fmt!("%s %s", vstore_to_str(cx, vs), ty)
}
_ => fmt!("%s[%s]", vstore_to_str(cx, vs), ty)
ty::vstore_fixed(_) => {
fmt!("[%s, .. %s]", mt_to_str(cx, mt), vstore_to_str(cx, vs))
}
_ => {
fmt!("%s%s", vstore_to_str(cx, vs), mt_to_str_wrapped(cx, "[", mt, "]"))
}
}
}
@ -460,7 +463,7 @@ pub fn ty_to_str(cx: ctxt, typ: t) -> ~str {
fmt!("%s%s", trait_store_to_str(cx, s), ty)
}
ty_evec(ref mt, vs) => {
vstore_ty_to_str(cx, fmt!("%s", mt_to_str(cx, mt)), vs)
vstore_ty_to_str(cx, mt, vs)
}
ty_estr(vs) => fmt!("%s%s", vstore_to_str(cx, vs), ~"str"),
ty_opaque_box => ~"@?",