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checker: fail if else isn't the last branch of match

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Enzo Baldisserri 2020-04-14 20:31:51 +02:00 committed by GitHub
parent 0c63f5c80d
commit 86402204a7
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GPG Key ID: 4AEE18F83AFDEB23
4 changed files with 80 additions and 55 deletions
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117
vlib/v/checker/checker.v
View File

@ -1355,69 +1355,80 @@ pub fn (c mut Checker) match_expr(node mut ast.MatchExpr) table.Type {
}
else {}
}
if !node.branches[node.branches.len - 1].is_else {
mut used_values_count := 0
for bi, branch in node.branches {
used_values_count += branch.exprs.len
for bi_ei, bexpr in branch.exprs {
match bexpr {
ast.Type {
tidx := table.type_idx(it.typ)
stidx := tidx.str()
all_possible_left_subtypes[stidx] = all_possible_left_subtypes[stidx] +
1
}
ast.EnumVal {
all_possible_left_enum_vals[it.val] = all_possible_left_enum_vals[it.val] +
1
}
else {}
}
mut has_else := node.branches[node.branches.len - 1].is_else
if !has_else {
for i, branch in node.branches {
if branch.is_else && i != node.branches.len - 1 {
c.error('`else` must be the last branch of `match`', branch.pos)
has_else = true
break
}
}
mut err := false
mut err_details := 'match must be exhaustive'
unhandled := []string
match type_sym.info {
table.SumType {
for k, v in all_possible_left_subtypes {
if v == 0 {
err = true
unhandled << '`' + c.table.type_to_str(table.new_type(k.int())) + '`'
}
if v > 1 {
err = true
multiple_type_name := '`' + c.table.type_to_str(table.new_type(k.int())) +
'`'
c.error('a match case for $multiple_type_name is handled more than once',
node.pos)
if !has_else {
mut used_values_count := 0
for bi, branch in node.branches {
used_values_count += branch.exprs.len
for bi_ei, bexpr in branch.exprs {
match bexpr {
ast.Type {
tidx := table.type_idx(it.typ)
stidx := tidx.str()
all_possible_left_subtypes[stidx] = all_possible_left_subtypes[stidx] +
1
}
ast.EnumVal {
all_possible_left_enum_vals[it.val] = all_possible_left_enum_vals[it.val] +
1
}
else {}
}
}
}
table.Enum {
for k, v in all_possible_left_enum_vals {
if v == 0 {
err = true
unhandled << '`.$k`'
}
if v > 1 {
err = true
multiple_enum_val := '`.$k`'
c.error('a match case for $multiple_enum_val is handled more than once',
node.pos)
mut err := false
mut err_details := 'match must be exhaustive'
unhandled := []string
match type_sym.info {
table.SumType {
for k, v in all_possible_left_subtypes {
if v == 0 {
err = true
unhandled << '`' + c.table.type_to_str(table.new_type(k.int())) + '`'
}
if v > 1 {
err = true
multiple_type_name := '`' + c.table.type_to_str(table.new_type(k.int())) +
'`'
c.error('a match case for $multiple_type_name is handled more than once',
node.pos)
}
}
}
table.Enum {
for k, v in all_possible_left_enum_vals {
if v == 0 {
err = true
unhandled << '`.$k`'
}
if v > 1 {
err = true
multiple_enum_val := '`.$k`'
c.error('a match case for $multiple_enum_val is handled more than once',
node.pos)
}
}
}
else {
err = true
}
}
else {
err = true
if err {
if unhandled.len > 0 {
err_details += ' (add match branches for: ' + unhandled.join(', ') + ' or an else{} branch)'
}
c.error(err_details, node.pos)
}
}
if err {
if unhandled.len > 0 {
err_details += ' (add match branches for: ' + unhandled.join(', ') + ' or an else{} branch)'
}
c.error(err_details, node.pos)
}
}
c.expected_type = cond_type
mut ret_type := table.void_type

7
vlib/v/checker/tests/inout/match_else_last_expr.out Normal file
View File

@ -0,0 +1,7 @@
vlib/v/checker/tests/inout/match_else_last_expr.v:4:3: error: `else` must be the last branch of `match`
2| match 1 {
3| 1 { println('1') }
4| else { println('else') }
~~~~~~
5| 4 { println('4') }
6| }

7
vlib/v/checker/tests/inout/match_else_last_expr.vv Normal file
View File

@ -0,0 +1,7 @@
fn main() {
match 1 {
1 { println('1') }
else { println('else') }
4 { println('4') }
}
}

4
vlib/v/parser/parser.v
View File

@ -1919,8 +1919,8 @@ fn (p mut Parser) match_expr() ast.MatchExpr {
// p.warn('match block')
stmts := p.parse_block()
pos := token.Position{
line_nr: match_first_pos.line_nr
pos: match_first_pos.pos
line_nr: branch_first_pos.line_nr
pos: branch_first_pos.pos
len: branch_last_pos.pos - branch_first_pos.pos + branch_last_pos.len
}
branches << ast.MatchBranch{