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[Lexer] Disallow '$' as a start of identifier, special handle '$' #6004

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Merged
merged 1 commit into from
Dec 21, 2016
Merged

[Lexer] Disallow '$' as a start of identifier, special handle '$' #6004

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10 changes: 9 additions & 1 deletion lib/Parse/Lexer.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -472,7 +472,7 @@ static bool isValidIdentifierContinuationCodePoint(uint32_t c) {
static bool isValidIdentifierStartCodePoint(uint32_t c) {
if (!isValidIdentifierContinuationCodePoint(c))
return false;
if (c < 0x80 && isDigit(c))
if (c < 0x80 && (isDigit(c) || c == '$'))
return false;

// N1518: Recommendations for extended identifier characters for C and C++
Expand Down Expand Up @@ -1385,6 +1385,14 @@ void Lexer::lexEscapedIdentifier() {
}
}

// Special case; allow '`$`'.
if (Quote[1] == '$' && Quote[2] == '`') {
CurPtr = Quote + 3;
formToken(tok::identifier, Quote);
NextToken.setEscapedIdentifier(true);
return;
}

// The backtick is punctuation.
CurPtr = IdentifierStart;
formToken(tok::backtick, Quote);
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7 changes: 7 additions & 0 deletions test/Parse/dollar_identifier.swift
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Expand Up @@ -54,3 +54,10 @@ func escapedDollarFunc() {
func `$`(`$`: Int) {} // no error
`$`(`$`: 25) // no error
}

func escapedDollarAnd() {
// FIXME: Bad diagnostics.
`$0` = 1 // expected-error {{expected expression}}
`$$` = 2 // expected-error {{expected numeric value following '$'}}
`$abc` = 3 // expected-error {{expected numeric value following '$'}}
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@rintaro rintaro Dec 20, 2016

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This is the Swift3 behavior. Diagnostics doesn't look nice.
We can improve this, but not for now.

}