Complete tagged template application

analysis/src/CompletionFrontEnd.ml

@@ -1127,6 +1127,45 @@ let completionWithParser1 ~currentFile ~debug ~offset ~path ~posCursor
       (* Case foo-> when the parser adds a ghost expression to the rhs
          so the apply expression does not include the cursor *)
       if setPipeResult ~lhs ~id:"" then setFound ()
+    (*
+       A dot completion for a tagged templated application.
+       Example:
+         sh`echo "meh"`.
+       or
+         sh`bar`.len
+    *)
+    | Pexp_apply
+        {
+          funct = {pexp_desc = Pexp_ident {txt = Lident "."; loc = _}};
+          args =
+            [(_, ({pexp_desc = Pexp_apply _} as innerExpr)); (_, fieldExpr)];
+        }
+      when Res_parsetree_viewer.is_tagged_template_literal innerExpr
+           && expr.pexp_loc |> Loc.hasPos ~pos:posBeforeCursor
+           || CompletionExpressions.isExprHole fieldExpr ->
+      exprToContextPath innerExpr
+      |> Option.iter (fun cpath ->
+             (* Determine the field name if present *)
+             let fieldName =
+               match fieldExpr.pexp_desc with
+               | Pexp_ident {txt = Lident fieldName}
+                 when Res_parsetree_viewer.is_tagged_template_literal innerExpr
+                 ->
+                 fieldName
+               (* This is likely to be an exprhole *)
+               | _ -> ""
+             in
+
+             setResult
+               (Cpath
+                  (CPField
+                     {
+                       contextPath = cpath;
+                       fieldName;
+                       posOfDot;
+                       exprLoc = expr.pexp_loc;
+                     }));
+             setFound ())
     | _ -> (
       if expr.pexp_loc |> Loc.hasPos ~pos:posNoWhite && !result = None then (
         setFound ();

tests/analysis_tests/tests/src/CompletionTaggedTemplate.res

@@ -0,0 +1,8 @@
+@module("meh") @taggedTemplate
+external meh: (array<string>, array<string>) => string = "default"
+
+// let x = meh`foo`.
+//                  ^com
+
+// let y = meh`bar`.len
+//                     ^com