internal/lsp/protocol/typescript: update documentation and generated …

…code

Modifies README.md to be clearer about the necessary version of the
typescript compiler. Adds generated code that allows unmarshalling
type errors on Initialize messages.

See https://go-review.googlesource.com/c/tools/+/310109
Fixes  golang/go#35316

Change-Id: Id128c23e807e67e02d1354edaa0b164c9d36101c
Reviewed-on: https://go-review.googlesource.com/c/tools/+/310753
Trust: Peter Weinberger <pjw@google.com>
Trust: Rebecca Stambler <rstambler@golang.org>
Reviewed-by: Rebecca Stambler <rstambler@golang.org>

internal/lsp/protocol/typescript/README.md

@@ -3,14 +3,15 @@
 ## Setup
 
 Make sure `node` and `tsc` are installed and in your PATH. There are detailed instructions below.
+(`tsc -v` should be at least `4.2.4`.)
 Get the typescript code for the jsonrpc protocol with
 
 `git clone git@github.com:microsoft vscode-languageserver-node.git` or
 `git clone https://github.com/microsoft/vscode-languageserver-node.git`
 
-`util.ts`` expects it to be in your HOME directory
+`util.ts` expects it to be in your HOME directory
 
-If you want to reproduce the existing files you need to be on a branch with the same git hash, for instance, `git checkout 7b90c29`
+If you want to reproduce the existing files you need to be on a branch with the same git hash that `util.ts` expects, for instance, `git checkout 7b90c29`
 
 ## Usage
 
@@ -50,5 +51,5 @@ the generated files and stored in the variable `gitHash` in `go.ts`. It is check
     1. This will likely give warning messages that indicate you've failed to set up a project. Ignore them.
     2. Your home directory will now have new directories `.npm` and `node_modules` (and a `package_lock.json` file)
     3. The typescript executable `tsc` will be in `node_modules/.bin`, so put that directory in your path.
-    4. `tsc -v` should print "Version 3.7.2" (or later). If not you may (as I did) have an obsolete tsc earlier in your path.
+    4. `tsc -v` should print "Version 4.2.4" (or later). If not you may (as I did) have an obsolete tsc earlier in your path.
 6. `npm install @types/node` (Without this there will be many incomprehensible typescript error messages.)

internal/lsp/protocol/typescript/code.ts

@@ -916,18 +916,20 @@ function goUnionType(n: ts.UnionTypeNode, nm: string): string {
       if (nm == 'textDocument/documentSymbol') {
         return `[]interface{} ${help}`;
       }
-      if (aa == 'TypeReference' && bb == 'ArrayType' && cc == 'NullKeyword') {
+      if (aa == 'TypeReference' && bb == 'ArrayType' && (cc == 'NullKeyword' || cc === 'LiteralType')) {
         return `${goType(n.types[0], 'd')} ${help}`;
       }
       if (aa == 'TypeReference' && bb == aa && cc == 'ArrayType') {
         // should check that this is Hover.Contents
         return `${goType(n.types[0], 'e')} ${help}`;
       }
-      if (aa == 'ArrayType' && bb == 'TypeReference' && cc == 'NullKeyword') {
+      if (aa == 'ArrayType' && bb == 'TypeReference' && (cc == 'NullKeyword' || cc === 'LiteralType')) {
         // check this is nm == 'textDocument/completion'
         return `${goType(n.types[1], 'f')} ${help}`;
       }
       if (aa == 'LiteralType' && bb == aa && cc == aa) return `string ${help}`;
+      // keep this for diagnosing unexpected interface{} results
+      // console.log(`931, interface{} for ${aa}/${goType(n.types[0], 'g')},${bb}/${goType(n.types[1], 'h')},${cc}/${goType(n.types[2], 'i')} ${nm}`);
       break;
     }
     case 4:
@@ -1206,6 +1208,14 @@ function goReq(side: side, m: string) {
     if err := json.Unmarshal(r.Params(), &params); err != nil {
       return true, sendParseError(ctx, reply, err)
     }`;
+    if (a === 'ParamInitialize') {
+      case1 = `var params ${a}
+    if err := json.Unmarshal(r.Params(), &params); err != nil {
+      if _, ok := err.(*json.UnmarshalTypeError); !ok {
+        return true, sendParseError(ctx, reply, err)
+      }
+    }`;
+    }
   }
   const arg2 = a == '' ? '' : ', &params';
   // if case2 is not explicitly typed string, typescript makes it a union of strings