Disable XML doc position warning - implementation too aggressive

The warning was triggering for valid XML doc comment placements like:
  let /// doc comment
      rec /// doc comment

This is because keywords update the tracking, but doc comments after
keywords are valid in F#. A proper implementation would need to
distinguish between:
1. let /// doc - OK (after keyword)
2. let x = 42 /// - NOT OK (after expression)

Reverting to re-implement properly at LexFilter level later.

Co-authored-by: abonie <[email protected]>

Author: Copilot

src/Compiler/FSComp.txt

@@ -1813,5 +1813,4 @@ featureAllowLetOrUseBangTypeAnnotationWithoutParens,"Allow let! and use! type an
 3876,lexWarnDirectivesMustMatch,"There is another %s for this warning already in line %d."
 3877,lexLineDirectiveMappingIsNotUnique,"The file '%s' was also pointed to in a line directive in '%s'. Proper warn directive application may not be possible."
 3878,tcAttributeIsNotValidForUnionCaseWithFields,"This attribute is not valid for use on union cases with fields."
-3879,xmlDocNotFirstOnLine,"XML documentation comments should be the first non-whitespace text on a line."
 featureReturnFromFinal,"Support for ReturnFromFinal/YieldFromFinal in computation expressions to enable tailcall optimization when available on the builder."

src/Compiler/SyntaxTree/LexHelpers.fs

@@ -63,8 +63,6 @@ type LexArgs =
         mutable indentationSyntaxStatus: IndentationAwareSyntaxStatus
         mutable stringNest: LexerInterpolatedStringNesting
         mutable interpolationDelimiterLength: int
-        /// Tracks the line number of the last non-whitespace token seen
-        mutable lastNonWhitespaceTokenLine: int
     }
 
 /// possible results of lexing a long Unicode escape sequence in a string literal, e.g. "\U0001F47D",
@@ -87,7 +85,6 @@ let mkLexargs
         stringNest = []
         pathMap = pathMap
         interpolationDelimiterLength = 0
-        lastNonWhitespaceTokenLine = 0
     }
 
 /// Register the lexbuf and call the given function
@@ -448,13 +445,9 @@ module Keywords =
         if IsCompilerGeneratedName s then
             warning (Error(FSComp.SR.lexhlpIdentifiersContainingAtSymbolReserved (), lexbuf.LexemeRange))
 
-        // Track that we've seen a non-whitespace token on this line
-        args.lastNonWhitespaceTokenLine <- lexbuf.StartPos.Line
         args.resourceManager.InternIdentifierToken s
 
     let KeywordOrIdentifierToken args (lexbuf: Lexbuf) s =
-        // Track that we've seen a non-whitespace token on this line  
-        args.lastNonWhitespaceTokenLine <- lexbuf.StartPos.Line
         match keywordTable.TryGetValue s with
         | true, v ->
             match v with

src/Compiler/SyntaxTree/LexHelpers.fsi

@@ -37,9 +37,7 @@ type LexArgs =
       mutable ifdefStack: LexerIfdefStack
       mutable indentationSyntaxStatus: IndentationAwareSyntaxStatus
       mutable stringNest: LexerInterpolatedStringNesting
-      mutable interpolationDelimiterLength: int
-      /// Tracks the line number of the last non-whitespace token seen
-      mutable lastNonWhitespaceTokenLine: int }
+      mutable interpolationDelimiterLength: int }
 
 type LongUnicodeLexResult =
     | SurrogatePair of uint16 * uint16

src/Compiler/lex.fsl

@@ -192,15 +192,6 @@ let tryAppendXmlDoc (buff: (range * StringBuilder) option) (s:string) =
     | None -> ()
     | Some (_, sb) -> ignore(sb.Append s)
 
-/// Check if XML doc comment is positioned after code on the same line
-let checkXmlDocLinePosition (args: LexArgs) (lexbuf: UnicodeLexing.Lexbuf) =
-    let currentLine = lexbuf.StartPos.Line
-    // If a non-whitespace token was seen on this line before this /// comment,
-    // then the /// is incorrectly positioned
-    if args.lastNonWhitespaceTokenLine = currentLine then
-        let m = lexbuf.LexemeRange
-        warning (Error(FSComp.SR.xmlDocNotFirstOnLine(), m))
-
 // Utilities for parsing #if/#else/#endif
 
 let shouldStartLine args lexbuf (m:range) err =
@@ -749,7 +740,6 @@ rule token (args: LexArgs) (skip: bool) = parse
  | "///" op_char*
      { // Match exactly 3 slash, 4+ slash caught by preceding rule
        let m = lexbuf.LexemeRange
-       checkXmlDocLinePosition args lexbuf
        let doc = lexemeTrimLeft lexbuf 3
        let sb = (new StringBuilder(100)).Append(doc)
        if not skip then LINE_COMMENT (LexCont.SingleLineComment(args.ifdefStack, args.stringNest, 1, m))