AddBackticksToIdentifierIfNeeded adds ticks for not word.

[nojaf]

Please provide a succinct description of the issue.

Repro steps

Local fsi:

#r @"C:\Users\fverdonck\Projects\fsharp\artifacts\bin\FSharp.Core\Debug\netstandard2.0\FSharp.Core.dll"
#r @"C:\Users\fverdonck\Projects\fsharp\artifacts\bin\FSharp.Compiler.Service\Debug\netstandard2.0\FSharp.Compiler.Service.dll"

FSharp.Compiler.Syntax.PrettyNaming.AddBackticksToIdentifierIfNeeded "not"
|> printfn "FSharp.Compiler.Syntax.PrettyNaming.AddBackticksToIdentifierIfNeeded :  %s"

dotnet artifacts\bin\fsi\Debug\net5.0\fsi.dll C:\Users\fverdonck\Projects\scripts\fsharp\ast-from-local-compiler.fsx

Expected behavior

In previews version of FCS, no ticks are added.

Actual behavior

``not``

Known workarounds

Provide a description of any known workarounds.

Related information

Provide any related information (optional):

FCS 41.0.0-preview.21472.3

[nojaf]

params and parallel should get ticks and do not get them.

[vzarytovskii]

Hm, interesting, it got changed in #12072, keywordsWithDescription was moved from the lexhelp to the PrettyNaming module, as a lookup table when we check whether we need to add backticks and not is in it (we didn't use it there prior to this change):

And here's the new logic by which we check whether we need to wrap it:

fsharp/src/fsharp/PrettyNaming.fs

Lines 257 to 265 in b3d46d4

	let IsIdentifierName (name: string) =
	not (keywordLookup.Contains name) &&
	not (IsUnencodedOpName name) &&
	not (IsUnencodedLegacyOpName name) &&
	let nameLen = name.Length
	nameLen > 0 &&
	IsIdentifierFirstCharacter name.[0] &&
	let rec loop i = (i >= nameLen || (IsIdentifierPartCharacter(name.[i]) && loop (i+1)))
	loop 1

The lookup in keywordLookup is new.

cc @dsyme

[dsyme]

Hmmm yes I see, it was incorrect to use "keywordsWithDescription", which is mis-named - some of the entries in that table are not keywords (e.g. not, which is a function in the standard library), and not all keywords are present (e.g. reserved ones like params and parallel).

[nojaf]

So a fix would be to renamed keywordsWithDescription and update

fsharp/src/fsharp/PrettyNaming.fs

Lines 158 to 235 in b3d46d4

	let keywordsWithDescription : (string * string) list =
	[ "abstract", FSComp.SR.keywordDescriptionAbstract()
	"and", FSComp.SR.keyworkDescriptionAnd()
	"as", FSComp.SR.keywordDescriptionAs()
	"assert", FSComp.SR.keywordDescriptionAssert()
	"base", FSComp.SR.keywordDescriptionBase()
	"begin", FSComp.SR.keywordDescriptionBegin()
	"class", FSComp.SR.keywordDescriptionClass()
	"const", FSComp.SR.keywordDescriptionConst()
	"default", FSComp.SR.keywordDescriptionDefault()
	"delegate", FSComp.SR.keywordDescriptionDelegate()
	"do", FSComp.SR.keywordDescriptionDo()
	"done", FSComp.SR.keywordDescriptionDone()
	"downcast", FSComp.SR.keywordDescriptionDowncast()
	"downto", FSComp.SR.keywordDescriptionDownto()
	"elif", FSComp.SR.keywordDescriptionElif()
	"else", FSComp.SR.keywordDescriptionElse()
	"end", FSComp.SR.keywordDescriptionEnd()
	"exception", FSComp.SR.keywordDescriptionException()
	"extern", FSComp.SR.keywordDescriptionExtern()
	"false", FSComp.SR.keywordDescriptionTrueFalse()
	"finally", FSComp.SR.keywordDescriptionFinally()
	"for", FSComp.SR.keywordDescriptionFor()
	"fun", FSComp.SR.keywordDescriptionFun()
	"function", FSComp.SR.keywordDescriptionFunction()
	"global", FSComp.SR.keywordDescriptionGlobal()
	"if", FSComp.SR.keywordDescriptionIf()
	"in", FSComp.SR.keywordDescriptionIn()
	"inherit", FSComp.SR.keywordDescriptionInherit()
	"inline", FSComp.SR.keywordDescriptionInline()
	"interface", FSComp.SR.keywordDescriptionInterface()
	"internal", FSComp.SR.keywordDescriptionInternal()
	"lazy", FSComp.SR.keywordDescriptionLazy()
	"let", FSComp.SR.keywordDescriptionLet()
	"let!", FSComp.SR.keywordDescriptionLetBang()
	"match", FSComp.SR.keywordDescriptionMatch()
	"match!", FSComp.SR.keywordDescriptionMatchBang()
	"member", FSComp.SR.keywordDescriptionMember()
	"module", FSComp.SR.keywordDescriptionModule()
	"mutable", FSComp.SR.keywordDescriptionMutable()
	"namespace", FSComp.SR.keywordDescriptionNamespace()
	"new", FSComp.SR.keywordDescriptionNew()
	"not", FSComp.SR.keywordDescriptionNot()
	"null", FSComp.SR.keywordDescriptionNull()
	"of", FSComp.SR.keywordDescriptionOf()
	"open", FSComp.SR.keywordDescriptionOpen()
	"or", FSComp.SR.keywordDescriptionOr()
	"override", FSComp.SR.keywordDescriptionOverride()
	"private", FSComp.SR.keywordDescriptionPrivate()
	"public", FSComp.SR.keywordDescriptionPublic()
	"rec", FSComp.SR.keywordDescriptionRec()
	"return", FSComp.SR.keywordDescriptionReturn()
	"return!", FSComp.SR.keywordDescriptionReturnBang()
	"static", FSComp.SR.keywordDescriptionStatic()
	"struct", FSComp.SR.keywordDescriptionStruct()
	"then", FSComp.SR.keywordDescriptionThen()
	"to", FSComp.SR.keywordDescriptionTo()
	"true", FSComp.SR.keywordDescriptionTrueFalse()
	"try", FSComp.SR.keywordDescriptionTry()
	"type", FSComp.SR.keywordDescriptionType()
	"upcast", FSComp.SR.keywordDescriptionUpcast()
	"use", FSComp.SR.keywordDescriptionUse()
	"use!", FSComp.SR.keywordDescriptionUseBang()
	"val", FSComp.SR.keywordDescriptionVal()
	"void", FSComp.SR.keywordDescriptionVoid()
	"when", FSComp.SR.keywordDescriptionWhen()
	"while", FSComp.SR.keywordDescriptionWhile()
	"with", FSComp.SR.keywordDescriptionWith()
	"yield", FSComp.SR.keywordDescriptionYield()
	"yield!", FSComp.SR.keywordDescriptionYieldBang()
	"->", FSComp.SR.keywordDescriptionRightArrow()
	"<-", FSComp.SR.keywordDescriptionLeftArrow()
	":>", FSComp.SR.keywordDescriptionCast()
	":?>", FSComp.SR.keywordDescriptionDynamicCast()
	"<@", FSComp.SR.keywordDescriptionTypedQuotation()
	"@>", FSComp.SR.keywordDescriptionTypedQuotation()
	"<@@", FSComp.SR.keywordDescriptionUntypedQuotation()
	"@@>", FSComp.SR.keywordDescriptionUntypedQuotation() ]

Remove not and add params and parallel?

[Happypig375]

Consider not in when 'T: not struct. Here, not is a keyword.

[dsyme]

Well, sort of. But in any case for the purposes of backtick escape it's not a keyword.

[nojaf]

@dsyme what was the outcome here again of fixing this?
Move keywordList from lexhelp.fs and use that in PrettyNaming?

fsharp/src/fsharp/lexhelp.fs

Lines 265 to 355 in 2f81541

	let private keywordList =
	[ FSHARP, "abstract", ABSTRACT
	ALWAYS, "and" ,AND
	ALWAYS, "as" ,AS
	ALWAYS, "assert" ,ASSERT
	ALWAYS, "asr" ,INFIX_STAR_STAR_OP "asr"
	ALWAYS, "base" ,BASE
	ALWAYS, "begin" ,BEGIN
	ALWAYS, "class" ,CLASS
	FSHARP, "const" ,CONST
	FSHARP, "default" ,DEFAULT
	FSHARP, "delegate" ,DELEGATE
	ALWAYS, "do" ,DO
	ALWAYS, "done" ,DONE
	FSHARP, "downcast" ,DOWNCAST
	ALWAYS, "downto" ,DOWNTO
	FSHARP, "elif" ,ELIF
	ALWAYS, "else" ,ELSE
	ALWAYS, "end" ,END
	ALWAYS, "exception" ,EXCEPTION
	FSHARP, "extern" ,EXTERN
	ALWAYS, "false" ,FALSE
	ALWAYS, "finally" ,FINALLY
	FSHARP, "fixed" ,FIXED
	ALWAYS, "for" ,FOR
	ALWAYS, "fun" ,FUN
	ALWAYS, "function" ,FUNCTION
	FSHARP, "global" ,GLOBAL
	ALWAYS, "if" ,IF
	ALWAYS, "in" ,IN
	ALWAYS, "inherit" ,INHERIT
	FSHARP, "inline" ,INLINE
	FSHARP, "interface" ,INTERFACE
	FSHARP, "internal" ,INTERNAL
	ALWAYS, "land" ,INFIX_STAR_DIV_MOD_OP "land"
	ALWAYS, "lazy" ,LAZY
	ALWAYS, "let" ,LET(false)
	ALWAYS, "lor" ,INFIX_STAR_DIV_MOD_OP "lor"
	ALWAYS, "lsl" ,INFIX_STAR_STAR_OP "lsl"
	ALWAYS, "lsr" ,INFIX_STAR_STAR_OP "lsr"
	ALWAYS, "lxor" ,INFIX_STAR_DIV_MOD_OP "lxor"
	ALWAYS, "match" ,MATCH
	FSHARP, "member" ,MEMBER
	ALWAYS, "mod" ,INFIX_STAR_DIV_MOD_OP "mod"
	ALWAYS, "module" ,MODULE
	ALWAYS, "mutable" ,MUTABLE
	FSHARP, "namespace" ,NAMESPACE
	ALWAYS, "new" ,NEW
	FSHARP, "null" ,NULL
	ALWAYS, "of" ,OF
	ALWAYS, "open" ,OPEN
	ALWAYS, "or" ,OR
	FSHARP, "override" ,OVERRIDE
	ALWAYS, "private" ,PRIVATE
	FSHARP, "public" ,PUBLIC
	ALWAYS, "rec" ,REC
	FSHARP, "return" ,YIELD(false)
	ALWAYS, "sig" ,SIG
	FSHARP, "static" ,STATIC
	ALWAYS, "struct" ,STRUCT
	ALWAYS, "then" ,THEN
	ALWAYS, "to" ,TO
	ALWAYS, "true" ,TRUE
	ALWAYS, "try" ,TRY
	ALWAYS, "type" ,TYPE
	FSHARP, "upcast" ,UPCAST
	FSHARP, "use" ,LET(true)
	ALWAYS, "val" ,VAL
	FSHARP, "void" ,VOID
	ALWAYS, "when" ,WHEN
	ALWAYS, "while" ,WHILE
	ALWAYS, "with" ,WITH
	FSHARP, "yield" ,YIELD(true)
	ALWAYS, "_" ,UNDERSCORE
	(*------- for prototyping and explaining offside rule *)
	FSHARP, "__token_OBLOCKSEP" ,OBLOCKSEP
	FSHARP, "__token_OWITH" ,OWITH
	FSHARP, "__token_ODECLEND" ,ODECLEND
	FSHARP, "__token_OTHEN" ,OTHEN
	FSHARP, "__token_OELSE" ,OELSE
	FSHARP, "__token_OEND" ,OEND
	FSHARP, "__token_ODO" ,ODO
	FSHARP, "__token_OLET" ,OLET(true)
	FSHARP, "__token_constraint",CONSTRAINT
	]
	(*------- reserved keywords which are ml-compatibility ids *)
	@ List.map (fun s -> (FSHARP,s,RESERVED))
	[ "break"; "checked"; "component"; "constraint"; "continue"
	"fori"; "include"; "mixin"
	"parallel"; "params"; "process"; "protected"; "pure"
	"sealed"; "trait"; "tailcall"; "virtual" ]