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implement leading bar and ampersand in types (#1286)

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Implements the [Leading `|` and `&` in types](https://rfcs.luau-lang.org/syntax-leading-bar-and-ampersand.html) RFC.

The changes to the parser are exactly as described in the RFC.

---------

Co-authored-by: Alexander McCord <11488393+alexmccord@users.noreply.github.com>
This commit is contained in:
Jack 2024-06-05 09:52:30 -05:00 committed by GitHub
parent 041b8ee4e7
commit 43bf7c4e05
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GPG Key ID: B5690EEEBB952194
2 changed files with 52 additions and 5 deletions
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34
Ast/src/Parser.cpp
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@ -17,6 +17,7 @@ LUAU_FASTINTVARIABLE(LuauParseErrorLimit, 100)
// flag so that we don't break production games by reverting syntax changes.
// See docs/SyntaxChanges.md for an explanation.
LUAU_FASTFLAGVARIABLE(DebugLuauDeferredConstraintResolution, false)
LUAU_FASTFLAGVARIABLE(LuauLeadingBarAndAmpersand, false)
namespace Luau
{
@ -1523,7 +1524,11 @@ AstType* Parser::parseFunctionTypeTail(const Lexeme& begin, AstArray<AstGenericT
AstType* Parser::parseTypeSuffix(AstType* type, const Location& begin)
{
TempVector<AstType*> parts(scratchType);
parts.push_back(type);
if (!FFlag::LuauLeadingBarAndAmpersand || type != nullptr)
{
parts.push_back(type);
}
incrementRecursionCounter("type annotation");
@ -1623,15 +1628,34 @@ AstTypeOrPack Parser::parseTypeOrPack()
AstType* Parser::parseType(bool inDeclarationContext)
{
unsigned int oldRecursionCount = recursionCounter;
// recursion counter is incremented in parseSimpleType
// recursion counter is incremented in parseSimpleType and/or parseTypeSuffix
Location begin = lexer.current().location;
AstType* type = parseSimpleType(/* allowPack= */ false, /* in declaration context */ inDeclarationContext).type;
if (FFlag::LuauLeadingBarAndAmpersand)
{
AstType* type = nullptr;
recursionCounter = oldRecursionCount;
Lexeme::Type c = lexer.current().type;
if (c != '|' && c != '&')
{
type = parseSimpleType(/* allowPack= */ false, /* in declaration context */ inDeclarationContext).type;
recursionCounter = oldRecursionCount;
}
return parseTypeSuffix(type, begin);
AstType* typeWithSuffix = parseTypeSuffix(type, begin);
recursionCounter = oldRecursionCount;
return typeWithSuffix;
}
else
{
AstType* type = parseSimpleType(/* allowPack= */ false, /* in declaration context */ inDeclarationContext).type;
recursionCounter = oldRecursionCount;
return parseTypeSuffix(type, begin);
}
}
// Type ::= nil | Name[`.' Name] [ `<' Type [`,' ...] `>' ] | `typeof' `(' expr `)' | `{' [PropList] `}'

23
tests/Parser.test.cpp
View File

@ -16,6 +16,7 @@ LUAU_FASTINT(LuauRecursionLimit);
LUAU_FASTINT(LuauTypeLengthLimit);
LUAU_FASTINT(LuauParseErrorLimit);
LUAU_FASTFLAG(DebugLuauDeferredConstraintResolution);
LUAU_FASTFLAG(LuauLeadingBarAndAmpersand);
namespace
{
@ -3167,4 +3168,26 @@ TEST_CASE_FIXTURE(Fixture, "read_write_table_properties")
LUAU_ASSERT(pr.errors.size() == 0);
}
TEST_CASE_FIXTURE(Fixture, "can_parse_leading_bar_unions_successfully")
{
ScopedFastFlag sff{FFlag::LuauLeadingBarAndAmpersand, true};
parse(R"(type A = | "Hello" | "World")");
}
TEST_CASE_FIXTURE(Fixture, "can_parse_leading_ampersand_intersections_successfully")
{
ScopedFastFlag sff{FFlag::LuauLeadingBarAndAmpersand, true};
parse(R"(type A = & { string } & { number })");
}
TEST_CASE_FIXTURE(Fixture, "mixed_leading_intersection_and_union_not_allowed")
{
ScopedFastFlag sff{FFlag::LuauLeadingBarAndAmpersand, true};
matchParseError("type A = & number | string | boolean", "Mixing union and intersection types is not allowed; consider wrapping in parentheses.");
matchParseError("type A = | number & string & boolean", "Mixing union and intersection types is not allowed; consider wrapping in parentheses.");
}
TEST_SUITE_END();