mirror of
https://github.com/carbon-language/carbon-lang.git
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Chandler Carruth
8be274cf60
Implement the toolchain side of proposal #7254, removing the `:!` binding syntax for generic and template parameters in favor of the keywords `generic`, `template`, and `runtime` plus contextual defaults for phase. For valid programs this is semantics-preserving: each binding resolves to the same phase, and produces the same SemIR, as it did under `:!`/`:`. The parser derives a binding's phase from its syntactic context plus any explicit phase keyword; new diagnostics and error recovery for misused keywords are described below. Implementation details for each component: - Lexer: remove the `:!` (`ColonExclaim`) token, move its virtual parse-node budget onto `:`, and add the `generic` and `runtime` keywords. - Parser: thread a `BindingContext` (`ExplicitParam`, `DeducedParam`, or `CompileTimeEntityParam`) from declaration introducers down through parameter lists to each binding pattern, using a one-token lookahead to distinguish a name-qualifier parameter list from a declaration's own final list. Parameters of a compile-time entity (`class`, `interface`, `constraint`, `choice`, `alias`, `export`, `namespace`) and deduced `[]` parameters default to checked generic; explicit function parameters and local bindings default to runtime. `HandleBindingPattern` resolves the phase from that context plus the keyword: a `generic` keyword needs no node of its own (the phase is carried by the binding's node kind), while a `runtime` keyword is preserved as a `RuntimeBindingName` node so `check` can name it in a diagnostic. A phase keyword that is merely redundant with the contextual default is diagnosed here, without invalidating the parse tree. - Check: a phase keyword that is invalid for its context (for example `runtime` on a checked-generic parameter) is diagnosed here, and recovers by building an error binding that still introduces the name so that later uses of it do not produce cascading errors. The removed `:!` syntax is now rejected as an ordinary parse error. The `form`/`:?`/`->?` ("extended types") portion of proposal #7254 is left for a separate change. Assisted-by: Claude Code
255 lines
11 KiB
C++
255 lines
11 KiB
C++
// Part of the Carbon Language project, under the Apache License v2.0 with LLVM
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// Exceptions. See /LICENSE for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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// This is an X-macro header. It does not use `#include` guards, and instead is
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// designed to be `#include`ed after the x-macro is defined in order for its
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// inclusion to expand to the desired output. Macro definitions are cleaned up
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// at the end of this file.
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//
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// Supported x-macros are:
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// - CARBON_TOKEN(Name)
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// Defines a token. Used directly when a token needs custom parsing, such as
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// integer literals.
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// - CARBON_SYMBOL_TOKEN(Name, Spelling)
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// Defines a symbol which has the provided spelling, such as `*`. Spellings
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// must be unique.
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// - CARBON_OPENING_GROUP_SYMBOL_TOKEN(Name, Spelling, ClosingName)
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// - CARBON_CLOSING_GROUP_SYMBOL_TOKEN(Name, Spelling, OpeningName)
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// These two macros together define matches opening and closing symbols,
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// such as `(` and `)`, and create an association between the two.
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// - CARBON_KEYWORD_TOKEN(Name, Spelling)
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// Defines a keyword which has the provided spelling, such as `if`.
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// Spellings must be unique.
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// - CARBON_DECL_INTRODUCER_TOKEN(Name, Spelling)
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// A declaration introducer keyword, such as `fn`.
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// - CARBON_TOKEN_WITH_VIRTUAL_NODE(TokenIndex)
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// Wrapped around one of the above _TOKEN macros, indicates that this
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// token has one additional virtual node in the parse tree.
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//
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// This tree represents the subset relationship between these macros, where if a
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// specific x-macro isn't defined, it'll fall back to the parent macro.
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#ifndef CARBON_TOKEN
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#define CARBON_TOKEN(Name)
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#endif
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// The error token comes first because we want it to get the zero value, which
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// will also be used in default initialization.
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CARBON_TOKEN(Error)
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#ifndef CARBON_SYMBOL_TOKEN
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#define CARBON_SYMBOL_TOKEN(Name, Spelling) CARBON_TOKEN(Name)
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#endif
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#ifndef CARBON_ONE_CHAR_SYMBOL_TOKEN
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#define CARBON_ONE_CHAR_SYMBOL_TOKEN(Name, Spelling) \
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CARBON_SYMBOL_TOKEN(Name, Spelling)
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#endif
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#ifndef CARBON_TOKEN_WITH_VIRTUAL_NODE
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#define CARBON_TOKEN_WITH_VIRTUAL_NODE(Name) Name
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#endif
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// Note that symbols need to be ordered from longest to shortest to effectively
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// provide max-munch lexing.
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// clang-format off
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CARBON_SYMBOL_TOKEN(GreaterGreaterEqual, ">>=")
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CARBON_SYMBOL_TOKEN(LessEqualGreater, "<=>")
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CARBON_SYMBOL_TOKEN(LessLessEqual, "<<=")
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CARBON_SYMBOL_TOKEN(MinusGreaterQuestion,"->?")
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CARBON_SYMBOL_TOKEN(AmpEqual, "&=")
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CARBON_SYMBOL_TOKEN(CaretEqual, "^=")
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CARBON_SYMBOL_TOKEN(ColonEqual, ":=")
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CARBON_SYMBOL_TOKEN(ColonQuestion, ":?")
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CARBON_SYMBOL_TOKEN(EqualEqual, "==")
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CARBON_SYMBOL_TOKEN(EqualGreater, "=>")
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CARBON_SYMBOL_TOKEN(ExclaimEqual, "!=")
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CARBON_SYMBOL_TOKEN(GreaterEqual, ">=")
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CARBON_SYMBOL_TOKEN(GreaterGreater, ">>")
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CARBON_SYMBOL_TOKEN(LessEqual, "<=")
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CARBON_SYMBOL_TOKEN(LessGreater, "<>")
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CARBON_SYMBOL_TOKEN(LessLess, "<<")
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CARBON_SYMBOL_TOKEN(LessMinus, "<-")
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CARBON_SYMBOL_TOKEN(MinusEqual, "-=")
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CARBON_SYMBOL_TOKEN(MinusGreater, "->")
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CARBON_SYMBOL_TOKEN(MinusMinus, "--")
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CARBON_SYMBOL_TOKEN(PercentEqual, "%=")
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CARBON_SYMBOL_TOKEN(PipeEqual, "|=")
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CARBON_SYMBOL_TOKEN(PlusEqual, "+=")
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CARBON_SYMBOL_TOKEN(PlusPlus, "++")
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CARBON_SYMBOL_TOKEN(SlashEqual, "/=")
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CARBON_SYMBOL_TOKEN(StarEqual, "*=")
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CARBON_SYMBOL_TOKEN(TildeEqual, "~=")
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CARBON_SYMBOL_TOKEN(Amp, "&")
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CARBON_SYMBOL_TOKEN(At, "@")
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CARBON_SYMBOL_TOKEN(Backslash, "\\")
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CARBON_SYMBOL_TOKEN(Caret, "^")
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CARBON_TOKEN_WITH_VIRTUAL_NODE(
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CARBON_SYMBOL_TOKEN(Colon, ":"))
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CARBON_SYMBOL_TOKEN(Equal, "=")
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CARBON_SYMBOL_TOKEN(Exclaim, "!")
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CARBON_SYMBOL_TOKEN(Greater, ">")
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CARBON_SYMBOL_TOKEN(Less, "<")
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CARBON_SYMBOL_TOKEN(Minus, "-")
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CARBON_SYMBOL_TOKEN(Percent, "%")
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CARBON_SYMBOL_TOKEN(Period, ".")
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CARBON_SYMBOL_TOKEN(Pipe, "|")
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CARBON_SYMBOL_TOKEN(Plus, "+")
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CARBON_SYMBOL_TOKEN(Question, "?")
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CARBON_SYMBOL_TOKEN(Slash, "/")
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CARBON_SYMBOL_TOKEN(Star, "*")
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CARBON_SYMBOL_TOKEN(Tilde, "~")
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// Some Carbon symbols are constructively exactly one character and cannot be
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// combined with any other characters to form new symbols. We can lex these
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// without needing to max-munch any other characters. These are typically
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// expected to be terminators or separators that need to compose with all other
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// parts of the grammar. Group symbols are also currently one-character symbols,
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// although we may choose to remove that if we need to add composite grouping
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// symbols in the future.
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CARBON_ONE_CHAR_SYMBOL_TOKEN(Comma, ",")
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CARBON_ONE_CHAR_SYMBOL_TOKEN(Semi, ";")
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// clang-format on
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#ifndef CARBON_OPENING_GROUP_SYMBOL_TOKEN
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#define CARBON_OPENING_GROUP_SYMBOL_TOKEN(Name, Spelling, ClosingName) \
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CARBON_ONE_CHAR_SYMBOL_TOKEN(Name, Spelling)
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#endif
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CARBON_OPENING_GROUP_SYMBOL_TOKEN(OpenParen, "(", CloseParen)
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CARBON_OPENING_GROUP_SYMBOL_TOKEN(OpenCurlyBrace, "{", CloseCurlyBrace)
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CARBON_OPENING_GROUP_SYMBOL_TOKEN(OpenSquareBracket, "[", CloseSquareBracket)
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#undef CARBON_OPENING_GROUP_SYMBOL_TOKEN
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#ifndef CARBON_CLOSING_GROUP_SYMBOL_TOKEN
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#define CARBON_CLOSING_GROUP_SYMBOL_TOKEN(Name, Spelling, OpeningName) \
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CARBON_ONE_CHAR_SYMBOL_TOKEN(Name, Spelling)
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#endif
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CARBON_CLOSING_GROUP_SYMBOL_TOKEN(CloseParen, ")", OpenParen)
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CARBON_CLOSING_GROUP_SYMBOL_TOKEN(CloseCurlyBrace, "}", OpenCurlyBrace)
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CARBON_CLOSING_GROUP_SYMBOL_TOKEN(CloseSquareBracket, "]", OpenSquareBracket)
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#undef CARBON_CLOSING_GROUP_SYMBOL_TOKEN
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#undef CARBON_ONE_CHAR_SYMBOL_TOKEN
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#undef CARBON_SYMBOL_TOKEN
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#ifndef CARBON_KEYWORD_TOKEN
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#define CARBON_KEYWORD_TOKEN(Name, Spelling) CARBON_TOKEN(Name)
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#endif
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#ifndef CARBON_DECL_INTRODUCER_TOKEN
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#define CARBON_DECL_INTRODUCER_TOKEN(Name, Spelling) \
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CARBON_KEYWORD_TOKEN(Name, Spelling)
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#endif
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// clang-format off
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CARBON_DECL_INTRODUCER_TOKEN(Adapt, "adapt")
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CARBON_DECL_INTRODUCER_TOKEN(Alias, "alias")
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CARBON_DECL_INTRODUCER_TOKEN(Base, "base")
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CARBON_DECL_INTRODUCER_TOKEN(Choice, "choice")
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CARBON_DECL_INTRODUCER_TOKEN(Class, "class")
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CARBON_DECL_INTRODUCER_TOKEN(Constraint, "constraint")
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CARBON_DECL_INTRODUCER_TOKEN(Export, "export")
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CARBON_TOKEN_WITH_VIRTUAL_NODE(
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CARBON_DECL_INTRODUCER_TOKEN(Fn, "fn"))
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CARBON_DECL_INTRODUCER_TOKEN(Impl, "impl")
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CARBON_DECL_INTRODUCER_TOKEN(Import, "import")
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CARBON_DECL_INTRODUCER_TOKEN(Interface, "interface")
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CARBON_DECL_INTRODUCER_TOKEN(Let, "let")
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CARBON_DECL_INTRODUCER_TOKEN(Library, "library")
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CARBON_DECL_INTRODUCER_TOKEN(MatchFirst, "match_first")
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CARBON_DECL_INTRODUCER_TOKEN(Namespace, "namespace")
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CARBON_DECL_INTRODUCER_TOKEN(Package, "package")
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CARBON_DECL_INTRODUCER_TOKEN(Require, "require")
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CARBON_TOKEN_WITH_VIRTUAL_NODE(
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CARBON_DECL_INTRODUCER_TOKEN(Var, "var"))
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CARBON_KEYWORD_TOKEN(Abstract, "abstract")
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CARBON_TOKEN_WITH_VIRTUAL_NODE(
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CARBON_KEYWORD_TOKEN(And, "and"))
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CARBON_KEYWORD_TOKEN(Array, "array")
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CARBON_KEYWORD_TOKEN(As, "as")
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CARBON_KEYWORD_TOKEN(Auto, "auto")
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CARBON_KEYWORD_TOKEN(Bool, "bool")
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CARBON_KEYWORD_TOKEN(Break, "break")
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CARBON_KEYWORD_TOKEN(Case, "case")
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CARBON_KEYWORD_TOKEN(Char, "char")
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CARBON_KEYWORD_TOKEN(Const, "const")
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CARBON_KEYWORD_TOKEN(Continue, "continue")
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CARBON_KEYWORD_TOKEN(Core, "Core")
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CARBON_KEYWORD_TOKEN(Cpp, "Cpp")
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CARBON_KEYWORD_TOKEN(Default, "default")
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CARBON_KEYWORD_TOKEN(Else, "else")
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CARBON_KEYWORD_TOKEN(Eval, "eval")
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CARBON_KEYWORD_TOKEN(Extend, "extend")
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CARBON_KEYWORD_TOKEN(Extern, "extern")
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CARBON_KEYWORD_TOKEN(False, "false")
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CARBON_KEYWORD_TOKEN(Final, "final")
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CARBON_KEYWORD_TOKEN(For, "for")
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CARBON_KEYWORD_TOKEN(Form, "form")
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CARBON_KEYWORD_TOKEN(Forall, "forall")
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CARBON_KEYWORD_TOKEN(Friend, "friend")
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CARBON_KEYWORD_TOKEN(Generic, "generic")
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CARBON_KEYWORD_TOKEN(If, "if")
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CARBON_KEYWORD_TOKEN(Impls, "impls")
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CARBON_KEYWORD_TOKEN(In, "in")
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CARBON_KEYWORD_TOKEN(Inline, "inline")
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CARBON_KEYWORD_TOKEN(Like, "like")
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CARBON_KEYWORD_TOKEN(Match, "match")
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CARBON_KEYWORD_TOKEN(MustEval, "musteval")
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CARBON_KEYWORD_TOKEN(Not, "not")
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CARBON_KEYWORD_TOKEN(Observe, "observe")
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CARBON_TOKEN_WITH_VIRTUAL_NODE(
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CARBON_KEYWORD_TOKEN(Or, "or"))
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CARBON_KEYWORD_TOKEN(Override, "override")
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CARBON_KEYWORD_TOKEN(Partial, "partial")
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CARBON_KEYWORD_TOKEN(Private, "private")
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CARBON_KEYWORD_TOKEN(Protected, "protected")
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CARBON_KEYWORD_TOKEN(Ref, "ref")
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CARBON_KEYWORD_TOKEN(Return, "return")
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CARBON_KEYWORD_TOKEN(Returned, "returned")
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CARBON_KEYWORD_TOKEN(Runtime, "runtime")
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CARBON_KEYWORD_TOKEN(SelfTypeIdentifier, "Self")
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CARBON_TOKEN_WITH_VIRTUAL_NODE(
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CARBON_KEYWORD_TOKEN(SelfValueIdentifier, "self"))
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CARBON_KEYWORD_TOKEN(Static, "static")
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// TODO: Although we provide a `str` type literal, it's not standardized.
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CARBON_KEYWORD_TOKEN(Str, "str")
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CARBON_KEYWORD_TOKEN(Template, "template")
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CARBON_KEYWORD_TOKEN(Then, "then")
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CARBON_KEYWORD_TOKEN(True, "true")
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CARBON_KEYWORD_TOKEN(Type, "type")
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// Underscore is tokenized as a keyword because it's part of identifiers.
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CARBON_KEYWORD_TOKEN(Underscore, "_")
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CARBON_KEYWORD_TOKEN(Unsafe, "unsafe")
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CARBON_KEYWORD_TOKEN(Unused, "unused")
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CARBON_KEYWORD_TOKEN(Virtual, "virtual")
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CARBON_KEYWORD_TOKEN(Val, "val")
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CARBON_TOKEN_WITH_VIRTUAL_NODE(
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CARBON_KEYWORD_TOKEN(Where, "where"))
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CARBON_KEYWORD_TOKEN(While, "while")
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// clang-format on
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#undef CARBON_DECL_INTRODUCER_TOKEN
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#undef CARBON_KEYWORD_TOKEN
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CARBON_TOKEN(Identifier)
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CARBON_TOKEN(IntLiteral)
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CARBON_TOKEN(RealLiteral)
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CARBON_TOKEN(StringLiteral)
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CARBON_TOKEN(CharLiteral)
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CARBON_TOKEN(IntTypeLiteral)
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CARBON_TOKEN(UnsignedIntTypeLiteral)
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CARBON_TOKEN(FloatTypeLiteral)
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CARBON_TOKEN(FileStart)
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CARBON_TOKEN(FileEnd)
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#undef CARBON_TOKEN
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#undef CARBON_TOKEN_WITH_VIRTUAL_NODE
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