fix issue where pattern completion would not be triggered (#999)

Author: zth

analysis/src/CompletionFrontEnd.ml

@@ -1026,8 +1026,10 @@ let completionWithParser1 ~currentFile ~debug ~offset ~path ~posCursor
       cases
       |> List.iter (fun (case : Parsetree.case) ->
              let oldScope = !scope in
-             if locHasCursor case.pc_rhs.pexp_loc = false then
-               completePattern ?contextPath:ctxPath case.pc_lhs;
+             if
+               locHasCursor case.pc_rhs.pexp_loc = false
+               && locHasCursor case.pc_lhs.ppat_loc
+             then completePattern ?contextPath:ctxPath case.pc_lhs;
              scopePattern ?contextPath:ctxPath case.pc_lhs;
              Ast_iterator.default_iterator.case iterator case;
              scope := oldScope);

analysis/tests/src/CompletionPattern.res

@@ -230,3 +230,15 @@ let make = (~thing: result<someVariant, unit>) => {
   | _ => ()
   }
 }
+
+type results = {
+  query: string,
+  nbHits: int,
+}
+
+type hitsUse = {results: results, hits: array<string>}
+
+let hitsUse = (): hitsUse => Obj.magic()
+
+// let {results: {query, nbHits}, } = hitsUse()
+//                               ^com

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

@@ -1207,3 +1207,19 @@ Path r
     "documentation": {"kind": "markdown", "value": "```rescript\nnest: nestedRecord\n```\n\n```rescript\ntype someRecord = {first: int, second: (bool, option<someRecord>), optThird: option<[#first | #second(someRecord)]>, nest: nestedRecord}\n```"}
   }]
 
+Complete src/CompletionPattern.res 242:33
+posCursor:[242:33] posNoWhite:[242:32] Found pattern:[242:7->242:35]
+Completable: Cpattern Value[hitsUse](Nolabel)->recordBody
+Package opens Pervasives.JsxModules.place holder
+Resolved opens 1 pervasives
+ContextPath Value[hitsUse](Nolabel)
+ContextPath Value[hitsUse]
+Path hitsUse
+[{
+    "label": "hits",
+    "kind": 5,
+    "tags": [],
+    "detail": "array<string>",
+    "documentation": {"kind": "markdown", "value": "```rescript\nhits: array<string>\n```\n\n```rescript\ntype hitsUse = {results: results, hits: array<string>}\n```"}
+  }]
+