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Allow \" in single-quoted interpolated string literals #11751

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Merged
merged 1 commit into from
Mar 23, 2021
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Allow \" in single-quoted interpolated string literals #11751

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9 changes: 9 additions & 0 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 @@ -1053,6 +1053,7 @@ object Scanners {
getRawStringLit()
}

// for interpolated strings
@annotation.tailrec private def getStringPart(multiLine: Boolean): Unit =
if (ch == '"')
if (multiLine) {
Expand All @@ -1069,6 +1070,14 @@ object Scanners {
setStrVal()
token = STRINGLIT
}
else if (ch == '\\' && !multiLine) {
putChar(ch)
nextRawChar()
if (ch == '"' || ch == '\\')
putChar(ch)
nextRawChar()
getStringPart(multiLine)
}
else if (ch == '$') {
nextRawChar()
if (ch == '$' || ch == '"') {
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4 changes: 3 additions & 1 deletion docs/docs/internals/syntax-3.1.md
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Original file line number Diff line number Diff line change
Expand Up @@ -70,8 +70,10 @@ stringElement ::= printableChar \ (‘"’ | ‘\’)
| charEscapeSeq
multiLineChars ::= {[‘"’] [‘"’] char \ ‘"’} {‘"’}
processedStringLiteral
::= alphaid ‘"’ {printableChar \ (‘"’ | ‘$’) | escape} ‘"’
::= alphaid ‘"’ {[‘\’] processedStringPart | ‘\\’ | ‘\"’} ‘"’
| alphaid ‘"""’ {[‘"’] [‘"’] char \ (‘"’ | ‘$’) | escape} {‘"’} ‘"""’
processedStringPart
::= printableChar \ (‘"’ | ‘$’ | ‘\’) | escape
escape ::= ‘$$’
| ‘$’ letter { letter | digit }
| ‘{’ Block [‘;’ whiteSpace stringFormat whiteSpace] ‘}’
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4 changes: 3 additions & 1 deletion docs/docs/internals/syntax.md
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Expand Up @@ -69,8 +69,10 @@ stringElement ::= printableChar \ (‘"’ | ‘\’)
| charEscapeSeq
multiLineChars ::= {[‘"’] [‘"’] char \ ‘"’} {‘"’}
processedStringLiteral
::= alphaid ‘"’ {printableChar \ (‘"’ | ‘$’) | escape} ‘"’
::= alphaid ‘"’ {[‘\’] processedStringPart | ‘\\’ | ‘\"’} ‘"’
| alphaid ‘"""’ {[‘"’] [‘"’] char \ (‘"’ | ‘$’) | escape} {‘"’} ‘"""’
processedStringPart
::= printableChar \ (‘"’ | ‘$’ | ‘\’) | escape
escape ::= ‘$$’
| ‘$’ letter { letter | digit }
| ‘{’ Block [‘;’ whiteSpace stringFormat whiteSpace] ‘}’
Expand Down
4 changes: 3 additions & 1 deletion docs/docs/reference/syntax.md
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Original file line number Diff line number Diff line change
Expand Up @@ -69,8 +69,10 @@ stringElement ::= printableChar \ (‘"’ | ‘\’)
| charEscapeSeq
multiLineChars ::= {[‘"’] [‘"’] char \ ‘"’} {‘"’}
processedStringLiteral
::= alphaid ‘"’ {printableChar \ (‘"’ | ‘$’) | escape} ‘"’
::= alphaid ‘"’ {[‘\’] processedStringPart | ‘\\’ | ‘\"’} ‘"’
| alphaid ‘"""’ {[‘"’] [‘"’] char \ (‘"’ | ‘$’) | escape} {‘"’} ‘"""’
processedStringPart
::= printableChar \ (‘"’ | ‘$’ | ‘\’) | escape
escape ::= ‘$$’
| ‘$’ letter { letter | digit }
| ‘{’ Block [‘;’ whiteSpace stringFormat whiteSpace] ‘}’
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9 changes: 9 additions & 0 deletions tests/neg/t6476.scala
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Original file line number Diff line number Diff line change
@@ -0,0 +1,9 @@
// only the last one doesn't parse
class C {
s"""\ """
s"""\\"""
s"""\"""
s"\ "
s"\\"
s"\" // error
} // error (should not be one)
8 changes: 8 additions & 0 deletions tests/neg/t6476b.scala
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@@ -0,0 +1,8 @@
class C {
val sa = s"""\""" // error: invalid escape
val sb = s"""\\"""
val sc = s"""\ """ // error: invalid escape
val ra = raw"""\"""
val rb = raw"""\\"""
val rc = raw"""\ """
}
13 changes: 13 additions & 0 deletions tests/run/t6476.check
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Original file line number Diff line number Diff line change
@@ -0,0 +1,13 @@
"Hello", Alice
"Hello", Alice
\"Hello\", Alice
\"Hello\", Alice
\"Hello\", Alice
\"Hello\", Alice
\TILT\
\\TILT\\
\\TILT\\
\TILT\
\\TILT\\
\\TILT\\
\TILT\
23 changes: 23 additions & 0 deletions tests/run/t6476.scala
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@@ -0,0 +1,23 @@
object Test {
def main(args: Array[String]): Unit = {
val person = "Alice"
println(s"\"Hello\", $person")
println(s"""\"Hello\", $person""")

println(f"\"Hello\", $person")
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It looks like this one was wrongly interpreted as \" instead of ". The check file differs with the one in Scala 2.

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I filed #11750 about that

println(f"""\"Hello\", $person""")

println(raw"\"Hello\", $person")
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Questions: Now that we have $" as way to escape " in any string interpolator, do we really need to special case \" in raw interpolators? Cant we just assume that raw"\" is "\"? How can we end with a \ in a raw now?

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do we really need to special case \" in raw interpolators?

Maybe I misunderstand, but there's no special case or change in the raw interpolator. The change here is that \" no longer closes the string literal, but the interpretation of \" is unchanged (raw"""\"""" and s"""\"""" are the same as before).

In my opinion we should do this change change and fix scala/bug#6476, even if we have $" now. This issue affected a lot of people, and will keep affecting a lot of people in the future, especially beginners (https://stackoverflow.com/questions/21086263/how-to-insert-double-quotes-into-string-with-interpolation-in-scala).

See also the (updated) PR description of scala/scala#8830 (comment).

Cant we just assume that raw"\" is "\"?

I'm not sure what you mean by that.

How can we end with a \ in a raw now?

Using triple-quote. The 2.13 compiler will even tell you that:

scala> raw"c:\"
           ^
       error: unclosed string literal; note that `\"` no longer closes single-quoted interpolated string literals since 2.13.6, you can use a triple-quoted string instead

If desired, I can include this message in Scala 3 as well.

println(raw"""\"Hello\", $person""")

println(s"\\TILT\\")
println(f"\\TILT\\")
println(raw"\\TILT\\")

println(s"""\\TILT\\""")
println(f"""\\TILT\\""")
println(raw"""\\TILT\\""")

println(raw"""\TILT\""")
}
}