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librustc: Disallow mutation and assignment in pattern guards, and modify

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the CFG for match statements.

There were two bugs in issue #14684. One was simply that the borrow
check didn't know about the correct CFG for match statements: the
pattern must be a predecessor of the guard. This disallows the bad
behavior if there are bindings in the pattern. But it isn't enough to
prevent the memory safety problem, because of wildcards; thus, this
patch introduces a more restrictive rule, which disallows assignments
and mutable borrows inside guards outright.

I discussed this with Niko and we decided this was the best plan of
action.

This breaks code that performs mutable borrows in pattern guards. Most
commonly, the code looks like this:

    impl Foo {
        fn f(&mut self, ...) {}
        fn g(&mut self, ...) {
            match bar {
                Baz if self.f(...) => { ... }
                _ => { ... }
            }
        }
    }

Change this code to not use a guard. For example:

    impl Foo {
        fn f(&mut self, ...) {}
        fn g(&mut self, ...) {
            match bar {
                Baz => {
                    if self.f(...) {
                        ...
                    } else {
                        ...
                    }
                }
                _ => { ... }
            }
        }
    }

Sometimes this can result in code duplication, but often it illustrates
a hidden memory safety problem.

Closes #14684.

[breaking-change]
This commit is contained in:
Patrick Walton 2014-07-25 15:18:19 -07:00
parent 66a0b528a6
commit b2eb88843d
10 changed files with 384 additions and 272 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

9
src/libfmt_macros/lib.rs
View File

@ -352,8 +352,13 @@ impl<'a> Parser<'a> {
None => {
let tmp = self.cur.clone();
match self.word() {
word if word.len() > 0 && self.consume('$') => {
CountIsName(word)
word if word.len() > 0 => {
if self.consume('$') {
CountIsName(word)
} else {
self.cur = tmp;
CountImplied
}
}
_ => {
self.cur = tmp;

41
src/librustc/middle/cfg/construct.rs
View File

@ -333,32 +333,37 @@ impl<'a> CFGBuilder<'a> {
// [discr]
// |
// v 2
// [guard1]
// [cond1]
// / \
// | \
// v 3 |
// [pat1] |
// |
// v 4 |
// [body1] v
// | [guard2]
// | / \
// | [body2] \
// | | ...
// | | |
// v 5 v v
// [....expr....]
// v 3 \
// [pat1] \
// | |
// v 4 |
// [guard1] |
// | |
// | |
// v 5 v
// [body1] [cond2]
// | / \
// | ... ...
// | | |
// v 6 v v
// [.....expr.....]
//
let discr_exit = self.expr(discr.clone(), pred); // 1
let expr_exit = self.add_node(expr.id, []);
let mut guard_exit = discr_exit;
let mut cond_exit = discr_exit;
for arm in arms.iter() {
guard_exit = self.opt_expr(arm.guard, guard_exit); // 2
cond_exit = self.add_dummy_node([cond_exit]); // 2
let pats_exit = self.pats_any(arm.pats.as_slice(),
guard_exit); // 3
let body_exit = self.expr(arm.body.clone(), pats_exit); // 4
self.add_contained_edge(body_exit, expr_exit); // 5
cond_exit); // 3
let guard_exit = self.opt_expr(arm.guard,
pats_exit); // 4
let body_exit = self.expr(arm.body.clone(),
guard_exit); // 5
self.add_contained_edge(body_exit, expr_exit); // 6
}
expr_exit
}

65
src/librustc/middle/check_match.rs
View File

@ -11,6 +11,10 @@
use middle::const_eval::{compare_const_vals, const_bool, const_float, const_nil, const_val};
use middle::const_eval::{const_expr_to_pat, eval_const_expr, lookup_const_by_id};
use middle::def::*;
use middle::expr_use_visitor::{ConsumeMode, Delegate, ExprUseVisitor, Init};
use middle::expr_use_visitor::{JustWrite, LoanCause, MutateMode};
use middle::expr_use_visitor::{WriteAndRead};
use middle::mem_categorization::cmt;
use middle::pat_util::*;
use middle::ty::*;
use middle::ty;
@ -143,7 +147,16 @@ fn check_expr(cx: &mut MatchCheckCtxt, ex: &Expr) {
arm.pats.as_slice());
}
// Second, check for unreachable arms.
// Second, if there is a guard on each arm, make sure it isn't
// assigning or borrowing anything mutably.
for arm in arms.iter() {
match arm.guard {
Some(guard) => check_for_mutation_in_guard(cx, &*guard),
None => {}
}
}
// Third, check for unreachable arms.
check_arms(cx, arms.as_slice());
// Finally, check if the whole match expression is exhaustive.
@ -903,3 +916,53 @@ 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>(cx: &'a MatchCheckCtxt<'a>, guard: &Expr) {
let mut checker = MutationChecker {
cx: cx,
};
let mut visitor = ExprUseVisitor::new(&mut checker, checker.cx.tcx);
visitor.walk_expr(guard);
}
struct MutationChecker<'a> {
cx: &'a MatchCheckCtxt<'a>,
}
impl<'a> Delegate for MutationChecker<'a> {
fn consume(&mut self, _: NodeId, _: Span, _: cmt, _: ConsumeMode) {}
fn consume_pat(&mut self, _: &Pat, _: cmt, _: ConsumeMode) {}
fn borrow(&mut self,
_: NodeId,
span: Span,
_: cmt,
_: Region,
kind: BorrowKind,
_: LoanCause) {
match kind {
MutBorrow => {
self.cx
.tcx
.sess
.span_err(span,
"cannot mutably borrow in a pattern guard")
}
ImmBorrow | UniqueImmBorrow => {}
}
}
fn decl_without_init(&mut self, _: NodeId, _: Span) {}
fn mutate(&mut self, _: NodeId, span: Span, _: cmt, mode: MutateMode) {
match mode {
JustWrite | WriteAndRead => {
self.cx
.tcx
.sess
.span_err(span, "cannot assign in a pattern guard")
}
Init => {}
}
}
}

2
src/librustc/middle/expr_use_visitor.rs
View File

@ -292,7 +292,7 @@ impl<'d,'t,TYPER:mc::Typer> ExprUseVisitor<'d,'t,TYPER> {
self.walk_expr(expr)
}
fn walk_expr(&mut self, expr: &ast::Expr) {
pub fn walk_expr(&mut self, expr: &ast::Expr) {
debug!("walk_expr(expr={})", expr.repr(self.tcx()));
self.walk_adjustment(expr);

22
src/librustdoc/html/render.rs
View File

@ -1730,17 +1730,19 @@ fn item_struct(w: &mut fmt::Formatter, it: &clean::Item,
}
}).peekable();
match s.struct_type {
doctree::Plain if fields.peek().is_some() => {
try!(write!(w, "<h2 class='fields'>Fields</h2>\n<table>"));
for field in fields {
try!(write!(w, "<tr><td id='structfield.{name}'>\
{stab}<code>{name}</code></td><td>",
stab = ConciseStability(&field.stability),
name = field.name.get_ref().as_slice()));
try!(document(w, field));
try!(write!(w, "</td></tr>"));
doctree::Plain => {
if fields.peek().is_some() {
try!(write!(w, "<h2 class='fields'>Fields</h2>\n<table>"));
for field in fields {
try!(write!(w, "<tr><td id='structfield.{name}'>\
{stab}<code>{name}</code></td><td>",
stab = ConciseStability(&field.stability),
name = field.name.get_ref().as_slice()));
try!(document(w, field));
try!(write!(w, "</td></tr>"));
}
try!(write!(w, "</table>"));
}
try!(write!(w, "</table>"));
}
_ => {}
}

393
src/libsyntax/parse/parser.rs
View File

@ -1954,19 +1954,6 @@ impl<'a> Parser<'a> {
token::BINOP(token::OR) | token::OROR => {
return self.parse_lambda_expr();
},
_ if self.eat_keyword(keywords::Proc) => {
let decl = self.parse_proc_decl();
let body = self.parse_expr();
let fakeblock = P(ast::Block {
view_items: Vec::new(),
stmts: Vec::new(),
expr: Some(body),
id: ast::DUMMY_NODE_ID,
rules: DefaultBlock,
span: body.span,
});
return self.mk_expr(lo, body.span.hi, ExprProc(decl, fakeblock));
},
// FIXME #13626: Should be able to stick in
// token::SELF_KEYWORD_NAME
token::IDENT(id @ ast::Ident{
@ -1978,48 +1965,6 @@ impl<'a> Parser<'a> {
ex = ExprPath(path);
hi = self.last_span.hi;
}
_ if self.eat_keyword(keywords::If) => {
return self.parse_if_expr();
},
_ if self.eat_keyword(keywords::For) => {
return self.parse_for_expr(None);
},
_ if self.eat_keyword(keywords::While) => {
return self.parse_while_expr();
},
_ if Parser::token_is_lifetime(&self.token) => {
let lifetime = self.get_lifetime();
self.bump();
self.expect(&token::COLON);
if self.eat_keyword(keywords::For) {
return self.parse_for_expr(Some(lifetime))
} else if self.eat_keyword(keywords::Loop) {
return self.parse_loop_expr(Some(lifetime))
} else {
self.fatal("expected `for` or `loop` after a label")
}
},
_ if self.eat_keyword(keywords::Loop) => {
return self.parse_loop_expr(None);
},
_ if self.eat_keyword(keywords::Continue) => {
let lo = self.span.lo;
let ex = if Parser::token_is_lifetime(&self.token) {
let lifetime = self.get_lifetime();
self.bump();
ExprAgain(Some(lifetime))
} else {
ExprAgain(None)
};
let hi = self.span.hi;
return self.mk_expr(lo, hi, ex);
},
_ if self.eat_keyword(keywords::Match) => {
return self.parse_match_expr();
},
_ if self.eat_keyword(keywords::Unsafe) => {
return self.parse_block_expr(lo, UnsafeBlock(ast::UserProvided));
},
token::LBRACKET => {
self.bump();
@ -2057,88 +2002,158 @@ impl<'a> Parser<'a> {
}
hi = self.last_span.hi;
},
_ if self.eat_keyword(keywords::Return) => {
// RETURN expression
if can_begin_expr(&self.token) {
let e = self.parse_expr();
hi = e.span.hi;
ex = ExprRet(Some(e));
} else { ex = ExprRet(None); }
},
_ if self.eat_keyword(keywords::Break) => {
// BREAK expression
_ => {
if self.eat_keyword(keywords::Proc) {
let decl = self.parse_proc_decl();
let body = self.parse_expr();
let fakeblock = P(ast::Block {
view_items: Vec::new(),
stmts: Vec::new(),
expr: Some(body),
id: ast::DUMMY_NODE_ID,
rules: DefaultBlock,
span: body.span,
});
return self.mk_expr(lo, body.span.hi, ExprProc(decl, fakeblock));
}
if self.eat_keyword(keywords::If) {
return self.parse_if_expr();
}
if self.eat_keyword(keywords::For) {
return self.parse_for_expr(None);
}
if self.eat_keyword(keywords::While) {
return self.parse_while_expr();
}
if Parser::token_is_lifetime(&self.token) {
let lifetime = self.get_lifetime();
self.bump();
ex = ExprBreak(Some(lifetime));
} else {
ex = ExprBreak(None);
self.expect(&token::COLON);
if self.eat_keyword(keywords::For) {
return self.parse_for_expr(Some(lifetime))
}
if self.eat_keyword(keywords::Loop) {
return self.parse_loop_expr(Some(lifetime))
}
self.fatal("expected `for` or `loop` after a label")
}
hi = self.span.hi;
},
_ if self.token == token::MOD_SEP ||
is_ident(&self.token) && !self.is_keyword(keywords::True) &&
!self.is_keyword(keywords::False) => {
let pth = self.parse_path(LifetimeAndTypesWithColons).path;
// `!`, as an operator, is prefix, so we know this isn't that
if self.token == token::NOT {
// MACRO INVOCATION expression
self.bump();
let ket = token::close_delimiter_for(&self.token)
.unwrap_or_else(|| self.fatal("expected open delimiter"));
self.bump();
let tts = self.parse_seq_to_end(&ket,
seq_sep_none(),
|p| p.parse_token_tree());
let hi = self.span.hi;
return self.mk_mac_expr(lo, hi, MacInvocTT(pth, tts, EMPTY_CTXT));
} else if self.token == token::LBRACE {
// This is a struct literal, unless we're prohibited from
// parsing struct literals here.
if self.restriction != RESTRICT_NO_STRUCT_LITERAL {
// It's a struct literal.
if self.eat_keyword(keywords::Loop) {
return self.parse_loop_expr(None);
}
if self.eat_keyword(keywords::Continue) {
let lo = self.span.lo;
let ex = if Parser::token_is_lifetime(&self.token) {
let lifetime = self.get_lifetime();
self.bump();
let mut fields = Vec::new();
let mut base = None;
ExprAgain(Some(lifetime))
} else {
ExprAgain(None)
};
let hi = self.span.hi;
return self.mk_expr(lo, hi, ex);
}
if self.eat_keyword(keywords::Match) {
return self.parse_match_expr();
}
if self.eat_keyword(keywords::Unsafe) {
return self.parse_block_expr(
lo,
UnsafeBlock(ast::UserProvided));
}
if self.eat_keyword(keywords::Return) {
// RETURN expression
if can_begin_expr(&self.token) {
let e = self.parse_expr();
hi = e.span.hi;
ex = ExprRet(Some(e));
} else {
ex = ExprRet(None);
}
} else if self.eat_keyword(keywords::Break) {
// BREAK expression
if Parser::token_is_lifetime(&self.token) {
let lifetime = self.get_lifetime();
self.bump();
ex = ExprBreak(Some(lifetime));
} else {
ex = ExprBreak(None);
}
hi = self.span.hi;
} else if self.token == token::MOD_SEP ||
is_ident(&self.token) &&
!self.is_keyword(keywords::True) &&
!self.is_keyword(keywords::False) {
let pth =
self.parse_path(LifetimeAndTypesWithColons).path;
while self.token != token::RBRACE {
if self.eat(&token::DOTDOT) {
base = Some(self.parse_expr());
break;
// `!`, as an operator, is prefix, so we know this isn't that
if self.token == token::NOT {
// MACRO INVOCATION expression
self.bump();
let ket = token::close_delimiter_for(&self.token)
.unwrap_or_else(|| {
self.fatal("expected open delimiter")
});
self.bump();
let tts = self.parse_seq_to_end(
&ket,
seq_sep_none(),
|p| p.parse_token_tree());
let hi = self.span.hi;
return self.mk_mac_expr(lo,
hi,
MacInvocTT(pth,
tts,
EMPTY_CTXT));
}
if self.token == token::LBRACE {
// This is a struct literal, unless we're prohibited
// from parsing struct literals here.
if self.restriction != RESTRICT_NO_STRUCT_LITERAL {
// It's a struct literal.
self.bump();
let mut fields = Vec::new();
let mut base = None;
while self.token != token::RBRACE {
if self.eat(&token::DOTDOT) {
base = Some(self.parse_expr());
break;
}
fields.push(self.parse_field());
self.commit_expr(fields.last().unwrap().expr,
&[token::COMMA],
&[token::RBRACE]);
}
fields.push(self.parse_field());
self.commit_expr(fields.last().unwrap().expr,
&[token::COMMA], &[token::RBRACE]);
}
if fields.len() == 0 && base.is_none() {
let last_span = self.last_span;
self.span_err(last_span,
"structure literal must either \
have at least one field or use \
functional structure update \
syntax");
}
if fields.len() == 0 && base.is_none() {
let last_span = self.last_span;
self.span_err(last_span,
"structure literal must either have at \
least one field or use functional \
structure update syntax");
hi = self.span.hi;
self.expect(&token::RBRACE);
ex = ExprStruct(pth, fields, base);
return self.mk_expr(lo, hi, ex);
}
hi = self.span.hi;
self.expect(&token::RBRACE);
ex = ExprStruct(pth, fields, base);
return self.mk_expr(lo, hi, ex);
}
}
hi = pth.span.hi;
ex = ExprPath(pth);
},
_ => {
// other literal expression
let lit = self.parse_lit();
hi = lit.span.hi;
ex = ExprLit(box(GC) lit);
hi = pth.span.hi;
ex = ExprPath(pth);
} else {
// other literal expression
let lit = self.parse_lit();
hi = lit.span.hi;
ex = ExprLit(box(GC) lit);
}
}
}
@ -2501,37 +2516,41 @@ impl<'a> Parser<'a> {
}
};
}
token::IDENT(_, _) if self.is_keyword(keywords::Box) => {
self.bump();
token::IDENT(_, _) => {
if self.is_keyword(keywords::Box) {
self.bump();
// Check for a place: `box(PLACE) EXPR`.
if self.eat(&token::LPAREN) {
// Support `box() EXPR` as the default.
if !self.eat(&token::RPAREN) {
let place = self.parse_expr();
self.expect(&token::RPAREN);
let subexpression = self.parse_prefix_expr();
hi = subexpression.span.hi;
ex = ExprBox(place, subexpression);
return self.mk_expr(lo, hi, ex);
// Check for a place: `box(PLACE) EXPR`.
if self.eat(&token::LPAREN) {
// Support `box() EXPR` as the default.
if !self.eat(&token::RPAREN) {
let place = self.parse_expr();
self.expect(&token::RPAREN);
let subexpression = self.parse_prefix_expr();
hi = subexpression.span.hi;
ex = ExprBox(place, subexpression);
return self.mk_expr(lo, hi, ex);
}
}
}
// Otherwise, we use the unique pointer default.
let subexpression = self.parse_prefix_expr();
hi = subexpression.span.hi;
// HACK: turn `box [...]` into a boxed-vec
ex = match subexpression.node {
ExprVec(..) | ExprRepeat(..) => {
let last_span = self.last_span;
self.obsolete(last_span, ObsoleteOwnedVector);
ExprVstore(subexpression, ExprVstoreUniq)
}
ExprLit(lit) if lit_is_str(lit) => {
ExprVstore(subexpression, ExprVstoreUniq)
}
_ => self.mk_unary(UnUniq, subexpression)
};
// Otherwise, we use the unique pointer default.
let subexpression = self.parse_prefix_expr();
hi = subexpression.span.hi;
// HACK: turn `box [...]` into a boxed-vec
ex = match subexpression.node {
ExprVec(..) | ExprRepeat(..) => {
let last_span = self.last_span;
self.obsolete(last_span, ObsoleteOwnedVector);
ExprVstore(subexpression, ExprVstoreUniq)
}
ExprLit(lit) if lit_is_str(lit) => {
ExprVstore(subexpression, ExprVstoreUniq)
}
_ => self.mk_unary(UnUniq, subexpression)
};
} else {
return self.parse_dot_or_call_expr()
}
}
_ => return self.parse_dot_or_call_expr()
}
@ -3832,17 +3851,6 @@ impl<'a> Parser<'a> {
}
SelfStatic
}
token::IDENT(..) if self.is_self_ident() => {
let self_ident = self.expect_self_ident();
// Determine whether this is the fully explicit form, `self:
// TYPE`.
if self.eat(&token::COLON) {
SelfExplicit(self.parse_ty(false), self_ident)
} else {
SelfValue(self_ident)
}
}
token::BINOP(token::STAR) => {
// Possibly "*self" or "*mut self" -- not supported. Try to avoid
// emitting cryptic "unexpected token" errors.
@ -3860,30 +3868,47 @@ impl<'a> Parser<'a> {
// error case, making bogus self ident:
SelfValue(special_idents::self_)
}
_ if Parser::token_is_mutability(&self.token) &&
self.look_ahead(1, |t| token::is_keyword(keywords::Self, t)) => {
mutbl_self = self.parse_mutability();
let self_ident = self.expect_self_ident();
token::IDENT(..) => {
if self.is_self_ident() {
let self_ident = self.expect_self_ident();
// Determine whether this is the fully explicit form, `self:
// TYPE`.
if self.eat(&token::COLON) {
SelfExplicit(self.parse_ty(false), self_ident)
// Determine whether this is the fully explicit form, `self:
// TYPE`.
if self.eat(&token::COLON) {
SelfExplicit(self.parse_ty(false), self_ident)
} else {
SelfValue(self_ident)
}
} else if Parser::token_is_mutability(&self.token) &&
self.look_ahead(1, |t| {
token::is_keyword(keywords::Self, t)
}) {
mutbl_self = self.parse_mutability();
let self_ident = self.expect_self_ident();
// Determine whether this is the fully explicit form,
// `self: TYPE`.
if self.eat(&token::COLON) {
SelfExplicit(self.parse_ty(false), self_ident)
} else {
SelfValue(self_ident)
}
} else if Parser::token_is_mutability(&self.token) &&
self.look_ahead(1, |t| *t == token::TILDE) &&
self.look_ahead(2, |t| {
token::is_keyword(keywords::Self, t)
}) {
mutbl_self = self.parse_mutability();
self.bump();
drop(self.expect_self_ident());
let last_span = self.last_span;
self.obsolete(last_span, ObsoleteOwnedSelf);
SelfStatic
} else {
SelfValue(self_ident)
SelfStatic
}
}
_ if Parser::token_is_mutability(&self.token) &&
self.look_ahead(1, |t| *t == token::TILDE) &&
self.look_ahead(2, |t| token::is_keyword(keywords::Self, t)) => {
mutbl_self = self.parse_mutability();
self.bump();
drop(self.expect_self_ident());
let last_span = self.last_span;
self.obsolete(last_span, ObsoleteOwnedSelf);
SelfStatic
}
_ => SelfStatic
_ => SelfStatic,
};
let explicit_self_sp = mk_sp(lo, self.span.hi);

27
src/test/compile-fail/borrowck-lend-flow-match.rs
View File

@ -11,9 +11,6 @@
#![allow(unused_variable)]
#![allow(dead_assignment)]
fn cond() -> bool { fail!() }
fn link<'a>(v: &'a uint, w: &mut &'a uint) -> bool { *w = v; true }
fn separate_arms() {
// Here both arms perform assignments, but only is illegal.
@ -31,28 +28,4 @@ fn separate_arms() {
x.clone(); // just to prevent liveness warnings
}
fn guard() {
// Here the guard performs a borrow. This borrow "infects" all
// subsequent arms (but not the prior ones).
let mut a = box 3u;
let mut b = box 4u;
let mut w = &*a;
match 22i {
_ if cond() => {
b = box 5u;
}
_ if link(&*b, &mut w) => {
b = box 6u; //~ ERROR cannot assign
}
_ => {
b = box 7u; //~ ERROR cannot assign
}
}
b = box 8; //~ ERROR cannot assign
}
fn main() {}

33
src/test/compile-fail/borrowck-mutate-in-guard.rs Normal file
View File

@ -0,0 +1,33 @@
// 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.
enum Enum<'a> {
A(&'a int),
B(bool),
}
fn foo() -> int {
let mut n = 42;
let mut x = A(&mut n);
match x {
A(_) if { x = B(false); false } => 1,
//~^ ERROR cannot assign in a pattern guard
A(_) if { let y = &mut x; *y = B(false); false } => 1,
//~^ ERROR cannot mutably borrow in a pattern guard
//~^^ ERROR cannot assign in a pattern guard
A(p) => *p,
B(_) => 2,
}
}
fn main() {
foo();
}

24
src/test/run-make/graphviz-flowgraph/f07.dot-expected.dot
View File

@ -7,14 +7,15 @@ digraph block {
N5[label="expr 7777i"];
N6[label="expr [7i, 77i, 777i, 7777i]"];
N7[label="expr match [7i, 77i, 777i, 7777i] { [x, y, ..] => x + y }"];
N8[label="local x"];
N9[label="local y"];
N10[label="pat .."];
N11[label="pat [x, y, ..]"];
N12[label="expr x"];
N13[label="expr y"];
N14[label="expr x + y"];
N15[label="block { match [7i, 77i, 777i, 7777i] { [x, y, ..] => x + y }; }"];
N8[label="(dummy_node)"];
N9[label="local x"];
N10[label="local y"];
N11[label="pat .."];
N12[label="pat [x, y, ..]"];
N13[label="expr x"];
N14[label="expr y"];
N15[label="expr x + y"];
N16[label="block { match [7i, 77i, 777i, 7777i] { [x, y, ..] => x + y }; }"];
N0 -> N2;
N2 -> N3;
N3 -> N4;
@ -27,7 +28,8 @@ digraph block {
N11 -> N12;
N12 -> N13;
N13 -> N14;
N14 -> N7;
N7 -> N15;
N15 -> N1;
N14 -> N15;
N15 -> N7;
N7 -> N16;
N16 -> N1;
}

40
src/test/run-make/graphviz-flowgraph/f13.dot-expected.dot
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@ -8,18 +8,20 @@ digraph block {
N6[label="local _y"];
N7[label="expr x"];
N8[label="expr match x { E13a => _y = 1, E13b(v) => _y = v + 1 }"];
N9[label="local E13a"];
N10[label="expr 1"];
N11[label="expr _y"];
N12[label="expr _y = 1"];
N13[label="local v"];
N14[label="pat E13b(v)"];
N15[label="expr v"];
N16[label="expr 1"];
N17[label="expr v + 1"];
N18[label="expr _y"];
N19[label="expr _y = v + 1"];
N20[label="block {\l let x = E13b(13);\l let _y;\l match x { E13a => _y = 1, E13b(v) => _y = v + 1 }\l}\l"];
N9[label="(dummy_node)"];
N10[label="local E13a"];
N11[label="expr 1"];
N12[label="expr _y"];
N13[label="expr _y = 1"];
N14[label="(dummy_node)"];
N15[label="local v"];
N16[label="pat E13b(v)"];
N17[label="expr v"];
N18[label="expr 1"];
N19[label="expr v + 1"];
N20[label="expr _y"];
N21[label="expr _y = v + 1"];
N22[label="block {\l let x = E13b(13);\l let _y;\l match x { E13a => _y = 1, E13b(v) => _y = v + 1 }\l}\l"];
N0 -> N2;
N2 -> N3;
N3 -> N4;
@ -30,15 +32,17 @@ digraph block {
N9 -> N10;
N10 -> N11;
N11 -> N12;
N12 -> N8;
N7 -> N13;
N13 -> N14;
N12 -> N13;
N13 -> N8;
N9 -> N14;
N14 -> N15;
N15 -> N16;
N16 -> N17;
N17 -> N18;
N18 -> N19;
N19 -> N8;
N8 -> N20;
N20 -> N1;
N19 -> N20;
N20 -> N21;
N21 -> N8;
N8 -> N22;
N22 -> N1;
}