fix triggering value completion vs named arg ambiguity

Author: zth

analysis/src/CompletionFrontEnd.ml

@@ -109,6 +109,7 @@ let extractJsxProps ~(compName : Longident.t Location.loc) ~args =
 let extractCompletableArgValueInfo exp =
   match exp.Parsetree.pexp_desc with
   | Pexp_ident {txt = Lident txt} -> Some txt
+  | Pexp_construct ({txt = Lident "()"}, _) -> Some ""
   | Pexp_construct ({txt = Lident txt}, _) -> Some txt
   | _ -> None
 
@@ -118,7 +119,11 @@ let isExprHole exp =
   | _ -> false
 
 let findArgCompletables ~(args : arg list) ~endPos ~posBeforeCursor
-    ~(contextPath : Completable.contextPath) ~posAfterFunExpr =
+    ~(contextPath : Completable.contextPath) ~posAfterFunExpr ~charBeforeCursor
+    =
+  let fnHasCursor =
+    posAfterFunExpr <= posBeforeCursor && posBeforeCursor < endPos
+  in
   let allNames =
     List.fold_right
       (fun arg allLabels ->
@@ -183,11 +188,34 @@ let findArgCompletables ~(args : arg list) ~endPos ~posBeforeCursor
         unlabelledCount := !unlabelledCount + 1;
         loop rest)
     | [] ->
-      if posAfterFunExpr <= posBeforeCursor && posBeforeCursor < endPos then
-        Some (CnamedArg (contextPath, "", allNames))
+      if fnHasCursor then
+        match charBeforeCursor with
+        | Some '~' -> Some (Completable.CnamedArg (contextPath, "", allNames))
+        | _ ->
+          Some
+            (Cargument
+               {
+                 functionContextPath = contextPath;
+                 argumentLabel =
+                   Unlabelled {argumentPosition = !unlabelledCount};
+                 prefix = "";
+               })
       else None
   in
-  loop args
+  match args with
+  (* Special handling for empty fn calls, e.g. `let _ = someFn(<com>)` *)
+  | [
+   {label = None; exp = {pexp_desc = Pexp_construct ({txt = Lident "()"}, _)}};
+  ]
+    when fnHasCursor ->
+    Some
+      (Completable.Cargument
+         {
+           functionContextPath = contextPath;
+           argumentLabel = Unlabelled {argumentPosition = 0};
+           prefix = "";
+         })
+  | _ -> loop args
 
 let rec exprToContextPath (e : Parsetree.expression) =
   match e.pexp_desc with
@@ -638,6 +666,7 @@ let completionWithParser1 ~currentFile ~debug ~offset ~path ~posCursor ~text =
               findArgCompletables ~contextPath ~args
                 ~endPos:(Loc.end_ expr.pexp_loc) ~posBeforeCursor
                 ~posAfterFunExpr:(Loc.end_ funExpr.pexp_loc)
+                ~charBeforeCursor
             | None -> None
           in
 

analysis/tests/src/CompletionFunctionArguments.res

@@ -61,10 +61,9 @@ let someFnTakingVariant = (
 // let _ = someFnTakingVariant(~configOpt2=O)
 //                                          ^com
 
-// --- UNIMPLEMENTED CASES ---
-// The following two cases does not complete to a values because of ambiguity - should it complete for a value, or for a named argument? We don't know whether the function has args or not when deciding, since we're just in the AST at that point. Can potentially be fixed in the future.
 // let _ = someOtherFn()
 //                     ^com
+
 // let _ = someOtherFn(1, 2, )
 //                          ^com
 

analysis/tests/src/expected/CompletionFunctionArguments.res.txt

@@ -158,30 +158,45 @@ Completable: Cargument Value[someFnTakingVariant](~configOpt2=O)
     "documentation": null
   }]
 
-Complete src/CompletionFunctionArguments.res 65:23
-posCursor:[65:23] posNoWhite:[65:22] Found expr:[65:11->65:24]
-Pexp_apply ...[65:11->65:22] (...[65:23->65:24])
-Completable: CnamedArg(Value[someOtherFn], "", [])
-Found type for function (bool, int, bool) => string
-[]
-
-Complete src/CompletionFunctionArguments.res 67:28
-posCursor:[67:28] posNoWhite:[67:27] Found expr:[67:11->67:30]
-Pexp_apply ...[67:11->67:22] (...[67:23->67:24], ...[67:26->67:27])
-Completable: CnamedArg(Value[someOtherFn], "", [])
-Found type for function (bool, int, bool) => string
-[]
+Complete src/CompletionFunctionArguments.res 63:23
+posCursor:[63:23] posNoWhite:[63:22] Found expr:[63:11->63:24]
+Pexp_apply ...[63:11->63:22] (...[63:23->63:24])
+Completable: Cargument Value[someOtherFn]($0)
+[{
+    "label": "true",
+    "kind": 4,
+    "tags": [],
+    "detail": "bool",
+    "documentation": null
+  }, {
+    "label": "false",
+    "kind": 4,
+    "tags": [],
+    "detail": "bool",
+    "documentation": null
+  }]
 
-Complete src/CompletionFunctionArguments.res 72:25
-posCursor:[72:25] posNoWhite:[72:24] Found expr:[72:11->72:30]
-Pexp_apply ...[72:11->72:17] (~isOff72:19->72:24=...[72:27->72:29])
-Completable: CnamedArg(Value[someFn], "", [isOff])
-Found type for function (~isOn: bool, ~isOff: bool=?, unit) => string
+Complete src/CompletionFunctionArguments.res 66:28
+posCursor:[66:28] posNoWhite:[66:27] Found expr:[66:11->66:30]
+Pexp_apply ...[66:11->66:22] (...[66:23->66:24], ...[66:26->66:27])
+Completable: Cargument Value[someOtherFn]($2)
 [{
-    "label": "isOn",
+    "label": "true",
+    "kind": 4,
+    "tags": [],
+    "detail": "bool",
+    "documentation": null
+  }, {
+    "label": "false",
     "kind": 4,
     "tags": [],
     "detail": "bool",
     "documentation": null
   }]
 
+Complete src/CompletionFunctionArguments.res 71:25
+posCursor:[71:25] posNoWhite:[71:24] Found expr:[71:11->71:30]
+Pexp_apply ...[71:11->71:17] (~isOff71:19->71:24=...[71:27->71:29])
+Completable: Cargument Value[someFn]($0)
+[]
+