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Make closing parens conditional stop tokens for skip
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Treat them as stop tokens only if there is a region that expects them
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@odersky
odersky committed Mar 17, 2022
1 parent 279f27b commit a35236e
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Showing 4 changed files with 189 additions and 10 deletions.
15 changes: 8 additions & 7 deletions compiler/src/dotty/tools/dotc/parsing/Scanners.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -291,7 +291,8 @@ object Scanners {
def atStop =
token == EOF
|| (currentRegion eq lastRegion)
&& (skipStopTokens.contains(token)
&& (stopSkipTokens.contains(token)
|| closingParens.contains(token) && lastRegion.toList.exists(_.closedBy == token)
|| token == OUTDENT && indentWidth(offset) < lastKnownIndentWidth)
// stop at OUTDENT if the new indentwidth is smaller than the indent width of
// currentRegion. This corrects for the problem that sometimes we don't see an INDENT
Expand Down Expand Up @@ -1521,7 +1522,7 @@ object Scanners {
* InBraces a pair of braces { ... }
* Indented a pair of <indent> ... <outdent> tokens
*/
abstract class Region:
abstract class Region(val closedBy: Token):
/** The region enclosing this one, or `null` for the outermost region */
def outer: Region | Null

Expand Down Expand Up @@ -1585,16 +1586,16 @@ object Scanners {
toList.map(r => s"(${r.indentWidth}, ${r.delimiter})").mkString(" in ")
end Region

case class InString(multiLine: Boolean, outer: Region) extends Region
case class InParens(prefix: Token, outer: Region) extends Region
case class InBraces(outer: Region) extends Region
case class InCase(outer: Region) extends Region
case class InString(multiLine: Boolean, outer: Region) extends Region(RBRACE)
case class InParens(prefix: Token, outer: Region) extends Region(prefix + 1)
case class InBraces(outer: Region) extends Region(RBRACE)
case class InCase(outer: Region) extends Region(OUTDENT)

/** A class describing an indentation region.
* @param width The principal indendation width
* @param prefix The token before the initial <indent> of the region
*/
case class Indented(width: IndentWidth, prefix: Token, outer: Region | Null) extends Region:
case class Indented(width: IndentWidth, prefix: Token, outer: Region | Null) extends Region(OUTDENT):
knownWidth = width

/** Other indendation widths > width of lines in the same region */
Expand Down
3 changes: 2 additions & 1 deletion compiler/src/dotty/tools/dotc/parsing/Tokens.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -287,7 +287,8 @@ object Tokens extends TokensCommon {

final val endMarkerTokens = identifierTokens | BitSet(IF, WHILE, FOR, MATCH, TRY, NEW, THROW, GIVEN, VAL, THIS)

final val skipStopTokens = BitSet(SEMI, COMMA, NEWLINE, NEWLINES, RBRACE, RPAREN, RBRACKET)
final val closingParens = BitSet(RPAREN, RBRACKET, RBRACE)
final val stopSkipTokens = BitSet(SEMI, COMMA, NEWLINE, NEWLINES)

final val softModifierNames = Set(nme.inline, nme.opaque, nme.open, nme.transparent, nme.infix)
}
144 changes: 144 additions & 0 deletions tests/neg/syntax-error-recovery.check
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Original file line number Diff line number Diff line change
@@ -0,0 +1,144 @@
-- [E040] Syntax Error: tests/neg/syntax-error-recovery.scala:3:16 -----------------------------------------------------
3 | if (x < 0 then // error
| ^^^^
| ')' expected, but 'then' found
-- [E040] Syntax Error: tests/neg/syntax-error-recovery.scala:11:16 ----------------------------------------------------
11 | if (x < 0 then // error
| ^^^^
| ')' expected, but 'then' found
-- [E040] Syntax Error: tests/neg/syntax-error-recovery.scala:19:4 -----------------------------------------------------
19 | if x == 0 then println(bar) // error
| ^^
| ')' expected, but 'if' found
-- [E040] Syntax Error: tests/neg/syntax-error-recovery.scala:23:12 ----------------------------------------------------
23 | if x < 0) then // error
| ^
| 'then' expected, but ')' found
-- [E040] Syntax Error: tests/neg/syntax-error-recovery.scala:32:16 ----------------------------------------------------
32 | if (x < 0 then // error
| ^^^^
| ')' expected, but 'then' found
-- [E040] Syntax Error: tests/neg/syntax-error-recovery.scala:40:16 ----------------------------------------------------
40 | if (x < 0 then // error
| ^^^^
| ')' expected, but 'then' found
-- [E040] Syntax Error: tests/neg/syntax-error-recovery.scala:48:4 -----------------------------------------------------
48 | if x == 0 then println(bar) // error
| ^^
| ')' expected, but 'if' found
-- [E040] Syntax Error: tests/neg/syntax-error-recovery.scala:52:12 ----------------------------------------------------
52 | if x < 0) then // error
| ^
| 'then' expected, but ')' found
-- [E018] Syntax Error: tests/neg/syntax-error-recovery.scala:59:14 ----------------------------------------------------
59 | foo2(foo2(,) // error // error
| ^
| expression expected but ',' found
|
| longer explanation available when compiling with `-explain`
-- [E018] Syntax Error: tests/neg/syntax-error-recovery.scala:59:15 ----------------------------------------------------
59 | foo2(foo2(,) // error // error
| ^
| expression expected but ')' found
|
| longer explanation available when compiling with `-explain`
-- [E040] Syntax Error: tests/neg/syntax-error-recovery.scala:62:8 -----------------------------------------------------
62 |// error
| ^
| ')' expected, but eof found
-- [E006] Not Found Error: tests/neg/syntax-error-recovery.scala:8:10 --------------------------------------------------
8 | println(bar) // error
| ^^^
| Not found: bar
|
| longer explanation available when compiling with `-explain`
-- [E006] Not Found Error: tests/neg/syntax-error-recovery.scala:15:10 -------------------------------------------------
15 | println(baz) // error
| ^^^
| Not found: baz
|
| longer explanation available when compiling with `-explain`
-- [E006] Not Found Error: tests/neg/syntax-error-recovery.scala:20:10 -------------------------------------------------
20 | println(bar) // error
| ^^^
| Not found: bar
|
| longer explanation available when compiling with `-explain`
-- [E006] Not Found Error: tests/neg/syntax-error-recovery.scala:27:10 -------------------------------------------------
27 | println(bam) // error
| ^^^
| Not found: bam
|
| longer explanation available when compiling with `-explain`
-- [E006] Not Found Error: tests/neg/syntax-error-recovery.scala:37:10 -------------------------------------------------
37 | println(bar) // error
| ^^^
| Not found: bar
|
| longer explanation available when compiling with `-explain`
-- [E006] Not Found Error: tests/neg/syntax-error-recovery.scala:44:10 -------------------------------------------------
44 | println(baz) // error
| ^^^
| Not found: baz
|
| longer explanation available when compiling with `-explain`
-- [E006] Not Found Error: tests/neg/syntax-error-recovery.scala:49:10 -------------------------------------------------
49 | println(bar) // error
| ^^^
| Not found: bar
|
| longer explanation available when compiling with `-explain`
-- [E006] Not Found Error: tests/neg/syntax-error-recovery.scala:56:10 -------------------------------------------------
56 | println(bam) // error
| ^^^
| Not found: bam
|
| longer explanation available when compiling with `-explain`
-- [E006] Not Found Error: tests/neg/syntax-error-recovery.scala:61:10 -------------------------------------------------
61 | println(bam) // error
| ^^^
| Not found: bam
|
| longer explanation available when compiling with `-explain`
-- [E129] Potential Issue Warning: tests/neg/syntax-error-recovery.scala:7:2 -------------------------------------------
6 | 2
7 | }
| ^
| A pure expression does nothing in statement position; you may be omitting necessary parentheses
|
| longer explanation available when compiling with `-explain`
-- [E129] Potential Issue Warning: tests/neg/syntax-error-recovery.scala:15:2 ------------------------------------------
14 | 2
15 | println(baz) // error
| ^
| A pure expression does nothing in statement position; you may be omitting necessary parentheses
|
| longer explanation available when compiling with `-explain`
-- [E129] Potential Issue Warning: tests/neg/syntax-error-recovery.scala:27:2 ------------------------------------------
26 | 2
27 | println(bam) // error
| ^
| A pure expression does nothing in statement position; you may be omitting necessary parentheses
|
| longer explanation available when compiling with `-explain`
-- [E129] Potential Issue Warning: tests/neg/syntax-error-recovery.scala:36:2 ------------------------------------------
35 | 2
36 | }
| ^
| A pure expression does nothing in statement position; you may be omitting necessary parentheses
|
| longer explanation available when compiling with `-explain`
-- [E129] Potential Issue Warning: tests/neg/syntax-error-recovery.scala:44:2 ------------------------------------------
43 | 2
44 | println(baz) // error
| ^
| A pure expression does nothing in statement position; you may be omitting necessary parentheses
|
| longer explanation available when compiling with `-explain`
-- [E129] Potential Issue Warning: tests/neg/syntax-error-recovery.scala:56:2 ------------------------------------------
55 | 2
56 | println(bam) // error
| ^
| A pure expression does nothing in statement position; you may be omitting necessary parentheses
|
| longer explanation available when compiling with `-explain`
37 changes: 35 additions & 2 deletions tests/neg/syntax-error-recovery.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -24,6 +24,39 @@ object Test {
1
else
2
println(bam)
println(bam) // error

}
}
object Test2:
def foo(x: Int) = {
if (x < 0 then // error
1
else
2
}
println(bar) // error

def foo2(x: Int) =
if (x < 0 then // error
1
else
2
println(baz) // error

def foo3(x: Int) =
foo2(x
if x == 0 then println(bar) // error
println(bar) // error

def foo4(x: Int) =
if x < 0) then // error
1
else
2
println(bam) // error

def foo5(x: Int) =
foo2(foo2(,) // error // error

println(bam) // error
// error

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