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Rollup merge of #48490 - petrochenkov:orpat, r=eddyb

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Implement multiple patterns with `|` in `if let` and `while let` (RFC 2175)

cc https://github.com/rust-lang/rust/issues/48215
This commit is contained in:
Manish Goregaokar 2018-02-24 15:52:17 -08:00 committed by GitHub
commit 9523c82543
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GPG Key ID: 4AEE18F83AFDEB23
12 changed files with 231 additions and 128 deletions
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12
src/librustc/hir/lowering.rs
View File

@ -2956,7 +2956,7 @@ impl<'a> LoweringContext<'a> {
// Desugar ExprIfLet
// From: `if let <pat> = <sub_expr> <body> [<else_opt>]`
ExprKind::IfLet(ref pat, ref sub_expr, ref body, ref else_opt) => {
ExprKind::IfLet(ref pats, ref sub_expr, ref body, ref else_opt) => {
// to:
//
// match <sub_expr> {
@ -2970,8 +2970,8 @@ impl<'a> LoweringContext<'a> {
{
let body = self.lower_block(body, false);
let body_expr = P(self.expr_block(body, ThinVec::new()));
let pat = self.lower_pat(pat);
arms.push(self.arm(hir_vec![pat], body_expr));
let pats = pats.iter().map(|pat| self.lower_pat(pat)).collect();
arms.push(self.arm(pats, body_expr));
}
// _ => [<else_opt>|()]
@ -3000,7 +3000,7 @@ impl<'a> LoweringContext<'a> {
// Desugar ExprWhileLet
// From: `[opt_ident]: while let <pat> = <sub_expr> <body>`
ExprKind::WhileLet(ref pat, ref sub_expr, ref body, opt_label) => {
ExprKind::WhileLet(ref pats, ref sub_expr, ref body, opt_label) => {
// to:
//
// [opt_ident]: loop {
@ -3021,8 +3021,8 @@ impl<'a> LoweringContext<'a> {
// `<pat> => <body>`
let pat_arm = {
let body_expr = P(self.expr_block(body, ThinVec::new()));
let pat = self.lower_pat(pat);
self.arm(hir_vec![pat], body_expr)
let pats = pats.iter().map(|pat| self.lower_pat(pat)).collect();
self.arm(pats, body_expr)
};
// `_ => break`

36
src/librustc_resolve/lib.rs
View File

@ -59,6 +59,7 @@ use syntax::ast::{Label, Local, Mutability, Pat, PatKind, Path};
use syntax::ast::{QSelf, TraitItemKind, TraitRef, Ty, TyKind};
use syntax::feature_gate::{feature_err, emit_feature_err, GateIssue};
use syntax::parse::token;
use syntax::ptr::P;
use syntax_pos::{Span, DUMMY_SP, MultiSpan};
use errors::{DiagnosticBuilder, DiagnosticId};
@ -2329,17 +2330,17 @@ impl<'a> Resolver<'a> {
// check that all of the arms in an or-pattern have exactly the
// same set of bindings, with the same binding modes for each.
fn check_consistent_bindings(&mut self, arm: &Arm) {
if arm.pats.is_empty() {
fn check_consistent_bindings(&mut self, pats: &[P<Pat>]) {
if pats.is_empty() {
return;
}
let mut missing_vars = FxHashMap();
let mut inconsistent_vars = FxHashMap();
for (i, p) in arm.pats.iter().enumerate() {
for (i, p) in pats.iter().enumerate() {
let map_i = self.binding_mode_map(&p);
for (j, q) in arm.pats.iter().enumerate() {
for (j, q) in pats.iter().enumerate() {
if i == j {
continue;
}
@ -2404,9 +2405,8 @@ impl<'a> Resolver<'a> {
self.resolve_pattern(&pattern, PatternSource::Match, &mut bindings_list);
}
// This has to happen *after* we determine which
// pat_idents are variants
self.check_consistent_bindings(arm);
// This has to happen *after* we determine which pat_idents are variants
self.check_consistent_bindings(&arm.pats);
walk_list!(self, visit_expr, &arm.guard);
self.visit_expr(&arm.body);
@ -2490,7 +2490,9 @@ impl<'a> Resolver<'a> {
&ident.node.name.as_str())
);
}
Some(..) if pat_src == PatternSource::Match => {
Some(..) if pat_src == PatternSource::Match ||
pat_src == PatternSource::IfLet ||
pat_src == PatternSource::WhileLet => {
// `Variant1(a) | Variant2(a)`, ok
// Reuse definition from the first `a`.
def = self.ribs[ValueNS].last_mut().unwrap().bindings[&ident.node];
@ -3480,11 +3482,16 @@ impl<'a> Resolver<'a> {
visit::walk_expr(self, expr);
}
ExprKind::IfLet(ref pattern, ref subexpression, ref if_block, ref optional_else) => {
ExprKind::IfLet(ref pats, ref subexpression, ref if_block, ref optional_else) => {
self.visit_expr(subexpression);
self.ribs[ValueNS].push(Rib::new(NormalRibKind));
self.resolve_pattern(pattern, PatternSource::IfLet, &mut FxHashMap());
let mut bindings_list = FxHashMap();
for pat in pats {
self.resolve_pattern(pat, PatternSource::IfLet, &mut bindings_list);
}
// This has to happen *after* we determine which pat_idents are variants
self.check_consistent_bindings(pats);
self.visit_block(if_block);
self.ribs[ValueNS].pop();
@ -3500,11 +3507,16 @@ impl<'a> Resolver<'a> {
});
}
ExprKind::WhileLet(ref pattern, ref subexpression, ref block, label) => {
ExprKind::WhileLet(ref pats, ref subexpression, ref block, label) => {
self.with_resolved_label(label, expr.id, |this| {
this.visit_expr(subexpression);
this.ribs[ValueNS].push(Rib::new(NormalRibKind));
this.resolve_pattern(pattern, PatternSource::WhileLet, &mut FxHashMap());
let mut bindings_list = FxHashMap();
for pat in pats {
this.resolve_pattern(pat, PatternSource::WhileLet, &mut bindings_list);
}
// This has to happen *after* we determine which pat_idents are variants
this.check_consistent_bindings(pats);
this.visit_block(block);
this.ribs[ValueNS].pop();
});

163
src/librustc_save_analysis/dump_visitor.rs
View File

@ -1031,6 +1031,81 @@ impl<'l, 'tcx: 'l, 'll, O: DumpOutput + 'll> DumpVisitor<'l, 'tcx, 'll, O> {
}
}
fn process_var_decl_multi(&mut self, pats: &'l [P<ast::Pat>]) {
let mut collector = PathCollector::new();
for pattern in pats {
// collect paths from the arm's patterns
collector.visit_pat(&pattern);
self.visit_pat(&pattern);
}
// process collected paths
for (id, i, sp, immut) in collector.collected_idents {
match self.save_ctxt.get_path_def(id) {
HirDef::Local(id) => {
let mut value = if immut == ast::Mutability::Immutable {
self.span.snippet(sp).to_string()
} else {
"<mutable>".to_string()
};
let hir_id = self.tcx.hir.node_to_hir_id(id);
let typ = self.save_ctxt
.tables
.node_id_to_type_opt(hir_id)
.map(|t| t.to_string())
.unwrap_or(String::new());
value.push_str(": ");
value.push_str(&typ);
if !self.span.filter_generated(Some(sp), sp) {
let qualname = format!("{}${}", i.to_string(), id);
let id = ::id_from_node_id(id, &self.save_ctxt);
let span = self.span_from_span(sp);
self.dumper.dump_def(
&Access {
public: false,
reachable: false,
},
Def {
kind: DefKind::Local,
id,
span,
name: i.to_string(),
qualname,
value: typ,
parent: None,
children: vec![],
decl_id: None,
docs: String::new(),
sig: None,
attributes: vec![],
},
);
}
}
HirDef::StructCtor(..) |
HirDef::VariantCtor(..) |
HirDef::Const(..) |
HirDef::AssociatedConst(..) |
HirDef::Struct(..) |
HirDef::Variant(..) |
HirDef::TyAlias(..) |
HirDef::AssociatedTy(..) |
HirDef::SelfTy(..) => {
self.dump_path_ref(id, &ast::Path::from_ident(sp, i));
}
def => error!(
"unexpected definition kind when processing collected idents: {:?}",
def
),
}
}
for (id, ref path) in collector.collected_paths {
self.process_path(id, path);
}
}
fn process_var_decl(&mut self, p: &'l ast::Pat, value: String) {
// The local could declare multiple new vars, we must walk the
@ -1622,17 +1697,21 @@ impl<'l, 'tcx: 'l, 'll, O: DumpOutput + 'll> Visitor<'l> for DumpVisitor<'l, 'tc
v.nest_scope(ex.id, |v| v.visit_expr(body))
});
}
ast::ExprKind::ForLoop(ref pattern, ref subexpression, ref block, _) |
ast::ExprKind::WhileLet(ref pattern, ref subexpression, ref block, _) => {
ast::ExprKind::ForLoop(ref pattern, ref subexpression, ref block, _) => {
let value = self.span.snippet(subexpression.span);
self.process_var_decl(pattern, value);
debug!("for loop, walk sub-expr: {:?}", subexpression.node);
self.visit_expr(subexpression);
visit::walk_block(self, block);
}
ast::ExprKind::IfLet(ref pattern, ref subexpression, ref block, ref opt_else) => {
let value = self.span.snippet(subexpression.span);
self.process_var_decl(pattern, value);
ast::ExprKind::WhileLet(ref pats, ref subexpression, ref block, _) => {
self.process_var_decl_multi(pats);
debug!("for loop, walk sub-expr: {:?}", subexpression.node);
self.visit_expr(subexpression);
visit::walk_block(self, block);
}
ast::ExprKind::IfLet(ref pats, ref subexpression, ref block, ref opt_else) => {
self.process_var_decl_multi(pats);
self.visit_expr(subexpression);
visit::walk_block(self, block);
opt_else.as_ref().map(|el| self.visit_expr(el));
@ -1661,79 +1740,7 @@ impl<'l, 'tcx: 'l, 'll, O: DumpOutput + 'll> Visitor<'l> for DumpVisitor<'l, 'tc
}
fn visit_arm(&mut self, arm: &'l ast::Arm) {
let mut collector = PathCollector::new();
for pattern in &arm.pats {
// collect paths from the arm's patterns
collector.visit_pat(&pattern);
self.visit_pat(&pattern);
}
// process collected paths
for (id, i, sp, immut) in collector.collected_idents {
match self.save_ctxt.get_path_def(id) {
HirDef::Local(id) => {
let mut value = if immut == ast::Mutability::Immutable {
self.span.snippet(sp).to_string()
} else {
"<mutable>".to_string()
};
let hir_id = self.tcx.hir.node_to_hir_id(id);
let typ = self.save_ctxt
.tables
.node_id_to_type_opt(hir_id)
.map(|t| t.to_string())
.unwrap_or(String::new());
value.push_str(": ");
value.push_str(&typ);
if !self.span.filter_generated(Some(sp), sp) {
let qualname = format!("{}${}", i.to_string(), id);
let id = ::id_from_node_id(id, &self.save_ctxt);
let span = self.span_from_span(sp);
self.dumper.dump_def(
&Access {
public: false,
reachable: false,
},
Def {
kind: DefKind::Local,
id,
span,
name: i.to_string(),
qualname,
value: typ,
parent: None,
children: vec![],
decl_id: None,
docs: String::new(),
sig: None,
attributes: vec![],
},
);
}
}
HirDef::StructCtor(..) |
HirDef::VariantCtor(..) |
HirDef::Const(..) |
HirDef::AssociatedConst(..) |
HirDef::Struct(..) |
HirDef::Variant(..) |
HirDef::TyAlias(..) |
HirDef::AssociatedTy(..) |
HirDef::SelfTy(..) => {
self.dump_path_ref(id, &ast::Path::from_ident(sp, i));
}
def => error!(
"unexpected definition kind when processing collected idents: {:?}",
def
),
}
}
for (id, ref path) in collector.collected_paths {
self.process_path(id, path);
}
self.process_var_decl_multi(&arm.pats);
walk_list!(self, visit_expr, &arm.guard);
self.visit_expr(&arm.body);
}

4
src/libsyntax/ast.rs
View File

@ -1085,7 +1085,7 @@ pub enum ExprKind {
/// `if let pat = expr { block } else { expr }`
///
/// This is desugared to a `match` expression.
IfLet(P<Pat>, P<Expr>, P<Block>, Option<P<Expr>>),
IfLet(Vec<P<Pat>>, P<Expr>, P<Block>, Option<P<Expr>>),
/// A while loop, with an optional label
///
/// `'label: while expr { block }`
@ -1095,7 +1095,7 @@ pub enum ExprKind {
/// `'label: while let pat = expr { block }`
///
/// This is desugared to a combination of `loop` and `match` expressions.
WhileLet(P<Pat>, P<Expr>, P<Block>, Option<Label>),
WhileLet(Vec<P<Pat>>, P<Expr>, P<Block>, Option<Label>),
/// A for loop, with an optional label
///
/// `'label: for pat in expr { block }`

9
src/libsyntax/feature_gate.rs
View File

@ -446,6 +446,9 @@ declare_features! (
// Use `?` as the Kleene "at most one" operator
(active, macro_at_most_once_rep, "1.25.0", Some(48075)),
// Multiple patterns with `|` in `if let` and `while let`
(active, if_while_or_patterns, "1.26.0", Some(48215)),
);
declare_features! (
@ -1618,6 +1621,12 @@ impl<'a> Visitor<'a> for PostExpansionVisitor<'a> {
ast::ExprKind::Catch(_) => {
gate_feature_post!(&self, catch_expr, e.span, "`catch` expression is experimental");
}
ast::ExprKind::IfLet(ref pats, ..) | ast::ExprKind::WhileLet(ref pats, ..) => {
if pats.len() > 1 {
gate_feature_post!(&self, if_while_or_patterns, e.span,
"multiple patterns in `if let` and `while let` are unstable");
}
}
_ => {}
}
visit::walk_expr(self, e);

8
src/libsyntax/fold.rs
View File

@ -1210,8 +1210,8 @@ pub fn noop_fold_expr<T: Folder>(Expr {id, node, span, attrs}: Expr, folder: &mu
folder.fold_block(tr),
fl.map(|x| folder.fold_expr(x)))
}
ExprKind::IfLet(pat, expr, tr, fl) => {
ExprKind::IfLet(folder.fold_pat(pat),
ExprKind::IfLet(pats, expr, tr, fl) => {
ExprKind::IfLet(pats.move_map(|pat| folder.fold_pat(pat)),
folder.fold_expr(expr),
folder.fold_block(tr),
fl.map(|x| folder.fold_expr(x)))
@ -1221,8 +1221,8 @@ pub fn noop_fold_expr<T: Folder>(Expr {id, node, span, attrs}: Expr, folder: &mu
folder.fold_block(body),
opt_label.map(|label| folder.fold_label(label)))
}
ExprKind::WhileLet(pat, expr, body, opt_label) => {
ExprKind::WhileLet(folder.fold_pat(pat),
ExprKind::WhileLet(pats, expr, body, opt_label) => {
ExprKind::WhileLet(pats.move_map(|pat| folder.fold_pat(pat)),
folder.fold_expr(expr),
folder.fold_block(body),
opt_label.map(|label| folder.fold_label(label)))

8
src/libsyntax/parse/parser.rs
View File

@ -3228,7 +3228,7 @@ impl<'a> Parser<'a> {
-> PResult<'a, P<Expr>> {
let lo = self.prev_span;
self.expect_keyword(keywords::Let)?;
let pat = self.parse_pat()?;
let pats = self.parse_pats()?;
self.expect(&token::Eq)?;
let expr = self.parse_expr_res(Restrictions::NO_STRUCT_LITERAL, None)?;
let thn = self.parse_block()?;
@ -3238,7 +3238,7 @@ impl<'a> Parser<'a> {
} else {
(thn.span, None)
};
Ok(self.mk_expr(lo.to(hi), ExprKind::IfLet(pat, expr, thn, els), attrs))
Ok(self.mk_expr(lo.to(hi), ExprKind::IfLet(pats, expr, thn, els), attrs))
}
// `move |args| expr`
@ -3329,13 +3329,13 @@ impl<'a> Parser<'a> {
span_lo: Span,
mut attrs: ThinVec<Attribute>) -> PResult<'a, P<Expr>> {
self.expect_keyword(keywords::Let)?;
let pat = self.parse_pat()?;
let pats = self.parse_pats()?;
self.expect(&token::Eq)?;
let expr = self.parse_expr_res(Restrictions::NO_STRUCT_LITERAL, None)?;
let (iattrs, body) = self.parse_inner_attrs_and_block()?;
attrs.extend(iattrs);
let span = span_lo.to(body.span);
return Ok(self.mk_expr(span, ExprKind::WhileLet(pat, expr, body, opt_label), attrs));
return Ok(self.mk_expr(span, ExprKind::WhileLet(pats, expr, body, opt_label), attrs));
}
// parse `loop {...}`, `loop` token already eaten

41
src/libsyntax/print/pprust.rs
View File

@ -1767,11 +1767,11 @@ impl<'a> State<'a> {
self.print_else(e.as_ref().map(|e| &**e))
}
// "another else-if-let"
ast::ExprKind::IfLet(ref pat, ref expr, ref then, ref e) => {
ast::ExprKind::IfLet(ref pats, ref expr, ref then, ref e) => {
self.cbox(INDENT_UNIT - 1)?;
self.ibox(0)?;
self.s.word(" else if let ")?;
self.print_pat(pat)?;
self.print_pats(pats)?;
self.s.space()?;
self.word_space("=")?;
self.print_expr_as_cond(expr)?;
@ -1805,10 +1805,10 @@ impl<'a> State<'a> {
self.print_else(elseopt)
}
pub fn print_if_let(&mut self, pat: &ast::Pat, expr: &ast::Expr, blk: &ast::Block,
pub fn print_if_let(&mut self, pats: &[P<ast::Pat>], expr: &ast::Expr, blk: &ast::Block,
elseopt: Option<&ast::Expr>) -> io::Result<()> {
self.head("if let")?;
self.print_pat(pat)?;
self.print_pats(pats)?;
self.s.space()?;
self.word_space("=")?;
self.print_expr_as_cond(expr)?;
@ -2109,8 +2109,8 @@ impl<'a> State<'a> {
ast::ExprKind::If(ref test, ref blk, ref elseopt) => {
self.print_if(test, blk, elseopt.as_ref().map(|e| &**e))?;
}
ast::ExprKind::IfLet(ref pat, ref expr, ref blk, ref elseopt) => {
self.print_if_let(pat, expr, blk, elseopt.as_ref().map(|e| &**e))?;
ast::ExprKind::IfLet(ref pats, ref expr, ref blk, ref elseopt) => {
self.print_if_let(pats, expr, blk, elseopt.as_ref().map(|e| &**e))?;
}
ast::ExprKind::While(ref test, ref blk, opt_label) => {
if let Some(label) = opt_label {
@ -2122,13 +2122,13 @@ impl<'a> State<'a> {
self.s.space()?;
self.print_block_with_attrs(blk, attrs)?;
}
ast::ExprKind::WhileLet(ref pat, ref expr, ref blk, opt_label) => {
ast::ExprKind::WhileLet(ref pats, ref expr, ref blk, opt_label) => {
if let Some(label) = opt_label {
self.print_ident(label.ident)?;
self.word_space(":")?;
}
self.head("while let")?;
self.print_pat(pat)?;
self.print_pats(pats)?;
self.s.space()?;
self.word_space("=")?;
self.print_expr_as_cond(expr)?;
@ -2664,6 +2664,20 @@ impl<'a> State<'a> {
self.ann.post(self, NodePat(pat))
}
fn print_pats(&mut self, pats: &[P<ast::Pat>]) -> io::Result<()> {
let mut first = true;
for p in pats {
if first {
first = false;
} else {
self.s.space()?;
self.word_space("|")?;
}
self.print_pat(p)?;
}
Ok(())
}
fn print_arm(&mut self, arm: &ast::Arm) -> io::Result<()> {
// I have no idea why this check is necessary, but here it
// is :(
@ -2674,16 +2688,7 @@ impl<'a> State<'a> {
self.ibox(0)?;
self.maybe_print_comment(arm.pats[0].span.lo())?;
self.print_outer_attributes(&arm.attrs)?;
let mut first = true;
for p in &arm.pats {
if first {
first = false;
} else {
self.s.space()?;
self.word_space("|")?;
}
self.print_pat(p)?;
}
self.print_pats(&arm.pats)?;
self.s.space()?;
if let Some(ref e) = arm.guard {
self.word_space("if")?;

8
src/libsyntax/visit.rs
View File

@ -705,15 +705,15 @@ pub fn walk_expr<'a, V: Visitor<'a>>(visitor: &mut V, expression: &'a Expr) {
visitor.visit_expr(subexpression);
visitor.visit_block(block);
}
ExprKind::IfLet(ref pattern, ref subexpression, ref if_block, ref optional_else) => {
visitor.visit_pat(pattern);
ExprKind::IfLet(ref pats, ref subexpression, ref if_block, ref optional_else) => {
walk_list!(visitor, visit_pat, pats);
visitor.visit_expr(subexpression);
visitor.visit_block(if_block);
walk_list!(visitor, visit_expr, optional_else);
}
ExprKind::WhileLet(ref pattern, ref subexpression, ref block, ref opt_label) => {
ExprKind::WhileLet(ref pats, ref subexpression, ref block, ref opt_label) => {
walk_list!(visitor, visit_label, opt_label);
visitor.visit_pat(pattern);
walk_list!(visitor, visit_pat, pats);
visitor.visit_expr(subexpression);
visitor.visit_block(block);
}

30
src/test/run-pass/rfc-2175-or-if-while-let/basic.rs Normal file
View File

@ -0,0 +1,30 @@
// Copyright 2017 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.
#![feature(if_while_or_patterns)]
enum E {
V(u8),
U(u8),
W,
}
use E::*;
fn main() {
let mut e = V(10);
if let V(x) | U(x) = e {
assert_eq!(x, 10);
}
while let V(x) | U(x) = e {
assert_eq!(x, 10);
e = W;
}
}

18
src/test/ui/feature-gate-if_while_or_patterns.rs Normal file
View File

@ -0,0 +1,18 @@
// Copyright 2018 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.
fn main() {
if let 0 | 1 = 0 { //~ ERROR multiple patterns in `if let` and `while let` are unstable
;
}
while let 0 | 1 = 1 { //~ ERROR multiple patterns in `if let` and `while let` are unstable
break;
}
}

22
src/test/ui/feature-gate-if_while_or_patterns.stderr Normal file
View File

@ -0,0 +1,22 @@
error[E0658]: multiple patterns in `if let` and `while let` are unstable (see issue #48215)
--> $DIR/feature-gate-if_while_or_patterns.rs:12:5
|
12 | / if let 0 | 1 = 0 { //~ ERROR multiple patterns in `if let` and `while let` are unstable
13 | | ;
14 | | }
| |_____^
|
= help: add #![feature(if_while_or_patterns)] to the crate attributes to enable
error[E0658]: multiple patterns in `if let` and `while let` are unstable (see issue #48215)
--> $DIR/feature-gate-if_while_or_patterns.rs:15:5
|
15 | / while let 0 | 1 = 1 { //~ ERROR multiple patterns in `if let` and `while let` are unstable
16 | | break;
17 | | }
| |_____^
|
= help: add #![feature(if_while_or_patterns)] to the crate attributes to enable
error: aborting due to 2 previous errors