Prefixed module nameof (#16743) (#16747)

Author: nojaf

docs/release-notes/.FSharp.Compiler.Service/8.0.202.md

@@ -1,3 +1,3 @@
 ### Fixed
 
-* `nameof Module` expressions and patterns are processed to link files in `--test:GraphBasedChecking`. ([PR #16570](https://github.com/dotnet/fsharp/pull/16570))
+`nameof Module` expressions and patterns are processed to link files in `--test:GraphBasedChecking`. ([PR #16570](https://github.com/dotnet/fsharp/pull/16570), [PR #16747](https://github.com/dotnet/fsharp/pull/16747))

src/Compiler/Driver/GraphChecking/FileContentMapping.fs

@@ -311,8 +311,27 @@ let visitSynTypeConstraint (tc: SynTypeConstraint) : FileContentEntry list =
 let inline (|NameofIdent|_|) (ident: Ident) =
     if ident.idText = "nameof" then ValueSome() else ValueNone
 
+/// nameof X.Y.Z can be used in expressions and patterns
+[<RequireQualifiedAccess; NoComparison>]
+type NameofResult =
+    /// Example: nameof X
+    /// Where X is a module name
+    | SingleIdent of potentialModuleName: Ident
+    /// Example: nameof X.Y.Z
+    /// Where Z is either a module name or something from inside module or namespace Y.
+    /// Both options need to be explored.
+    | LongIdent of longIdent: LongIdent
+
+let visitNameofResult (nameofResult: NameofResult) : FileContentEntry =
+    match nameofResult with
+    | NameofResult.SingleIdent moduleName -> visitIdentAsPotentialModuleName moduleName
+    | NameofResult.LongIdent longIdent ->
+        // In this case the last part of the LongIdent could be a module name.
+        // So we should not cut off the last part.
+        FileContentEntry.PrefixedIdentifier(longIdentToPath false longIdent)
+
 /// Special case of `nameof Module` type of expression
-let (|NameofExpr|_|) (e: SynExpr) =
+let (|NameofExpr|_|) (e: SynExpr) : NameofResult option =
     let rec stripParen (e: SynExpr) =
         match e with
         | SynExpr.Paren(expr = expr) -> stripParen expr
@@ -321,14 +340,20 @@ let (|NameofExpr|_|) (e: SynExpr) =
     match e with
     | SynExpr.App(flag = ExprAtomicFlag.NonAtomic; isInfix = false; funcExpr = SynExpr.Ident NameofIdent; argExpr = moduleNameExpr) ->
         match stripParen moduleNameExpr with
-        | SynExpr.Ident moduleNameIdent -> Some moduleNameIdent
+        | SynExpr.Ident moduleNameIdent -> Some(NameofResult.SingleIdent moduleNameIdent)
+        | SynExpr.LongIdent(longDotId = longIdent) ->
+            match longIdent.LongIdent with
+            | [] -> None
+            // This is highly unlikely to be produced by the parser
+            | [ moduleNameIdent ] -> Some(NameofResult.SingleIdent moduleNameIdent)
+            | lid -> Some(NameofResult.LongIdent(lid))
         | _ -> None
     | _ -> None
 
 let visitSynExpr (e: SynExpr) : FileContentEntry list =
     let rec visit (e: SynExpr) (continuation: FileContentEntry list -> FileContentEntry list) : FileContentEntry list =
         match e with
-        | NameofExpr moduleNameIdent -> continuation [ visitIdentAsPotentialModuleName moduleNameIdent ]
+        | NameofExpr nameofResult -> continuation [ visitNameofResult nameofResult ]
         | SynExpr.Const _ -> continuation []
         | SynExpr.Paren(expr = expr) -> visit expr continuation
         | SynExpr.Quote(operator = operator; quotedExpr = quotedExpr) ->
@@ -552,18 +577,22 @@ let (|NameofPat|_|) (pat: SynPat) =
     | SynPat.LongIdent(longDotId = SynLongIdent(id = [ NameofIdent ]); typarDecls = None; argPats = SynArgPats.Pats [ moduleNamePat ]) ->
         match stripPats moduleNamePat with
         | SynPat.LongIdent(
-            longDotId = SynLongIdent.SynLongIdent(id = [ moduleNameIdent ]; dotRanges = []; trivia = [ None ])
+            longDotId = SynLongIdent.SynLongIdent(id = longIdent)
             extraId = None
             typarDecls = None
             argPats = SynArgPats.Pats []
-            accessibility = None) -> Some moduleNameIdent
+            accessibility = None) ->
+            match longIdent with
+            | [] -> None
+            | [ moduleNameIdent ] -> Some(NameofResult.SingleIdent moduleNameIdent)
+            | lid -> Some(NameofResult.LongIdent lid)
         | _ -> None
     | _ -> None
 
 let visitPat (p: SynPat) : FileContentEntry list =
     let rec visit (p: SynPat) (continuation: FileContentEntry list -> FileContentEntry list) : FileContentEntry list =
         match p with
-        | NameofPat moduleNameIdent -> continuation [ visitIdentAsPotentialModuleName moduleNameIdent ]
+        | NameofPat moduleNameIdent -> continuation [ visitNameofResult moduleNameIdent ]
         | SynPat.Paren(pat = pat) -> visit pat continuation
         | SynPat.Typed(pat = pat; targetType = t) -> visit pat (fun nodes -> nodes @ visitSynType t)
         | SynPat.Const _ -> continuation []

tests/FSharp.Compiler.ComponentTests/TypeChecks/Graph/Scenarios.fs

@@ -796,6 +796,8 @@ type Foo = class end
                 sourceFile
                     "Program"
                     """
+module Program
+
 printfn "Hello"
 """
                     Set.empty
@@ -907,6 +909,35 @@ do
 module Bar
 
 let _ = nameof ((Foo))
+"""
+                    (set [| 0 |])
+            ]
+        scenario
+            "prefixed module name in nameof expression"
+            [
+                sourceFile "A.fs" "module X.Y.Z" Set.empty
+                sourceFile
+                    "B.fs"
+                    """
+module B
+
+open System.ComponentModel
+
+[<Description(nameof X.Y.Z)>]
+let v = 2
+"""
+                    (set [| 0 |])
+            ]
+        scenario
+            "prefixed module name in nameof pattern"
+            [
+                sourceFile "A.fs" "module X.Y.Z" Set.empty
+                sourceFile
+                    "B.fs"
+                    """
+module B
+
+do ignore (match "" with | nameof X.Y.Z -> () | _ -> ())
 """
                     (set [| 0 |])
             ]