Editor support for link tag (microsoft#41877)

* Initial scribbles

* Compiles but provides spans instead of location pairs

Probably need to fork the services/server types and provide a conversion
with Session.toFileSpan. Not sure where to put the conversion.

* Switch to DocumentSpan

In theory this is already better supported, but not sure practise bears
that out.

* Builds w/protocol types + conversions

* cleanup:better names and scrub TODOs

* fix test harness too

* Misc

1. Simplify protocol after talking to @mjbvz.
2. Add more tests.
3. Initial notes about where to add parsing.

* Parse and store links in the compiler

The text of the link is still stored in the comment text, but that's now
kept in an object instead of just a string. Each link has the parse for
the entity reference, if there is one.

Needs lots more tests -- this just makes all the existing jsdoc tests
pass.

* more tests and some fixes

* Fix other failing tests

* fix bad merge

* polish parser

* improve names and array types

* slight tweaks

* remove some done TODOs

* more tests + resulting fixes

* add+fix cross-module tests

* Support `@see {@link`

Plus find-all-refs support equivalent to @see's.

* add server test

* Make comments actually part of the AST

* Add span for link.name in language service/protocol

* Make checker optional in getJSDocTags

Also change to JSDocCommentText from JSDocCommentComment

* Use getTokenValue instead of getTokenText

Measure twice, slice once

* Add missing support for top-level links

The language service and protocol were missing support for top-level
links. This commit adds that plumbing.

* add string back to comment type in node constructors

* Full parse of link tags and jsdoc comment text

- Doesn't pass fourslash yet, I'm going to switch to baselines for
  failures there.
- Still needs some work on the protocol to convert file+offset to
  file+line+offset.

* fix lint

* Fix missing newlines in inferFromUsage codefix

* Parse jsdoc comments as text node/link array

And switch to line+character offsets in the protocol

* Fix fourslash tests

Mostly ones that can't be baselined, but I switched a couple more over
to baselines

* Improve types and documentation

* Test+fix @link emit, scrub other TODOs

* update API baselines

* test that goto-def works with @link

* Split link displaypart into 3

One for link prefix and suffix, one for link name, and one for link
text.

* update baselines

* Provide JSDocTagInfo.text: string to full clients by default

Instead of upgrading them to displayparts.

* Real server tests

* Disambiguate {@link} and @param x {type}

They are ambiguous; previously the parser preferred the type
interpretation, but will now look ahead and parse links instead when the
prefix is `{@link`.

* Add explanatory comment in test

* fix location in richResponse in protocol

* update API baseline

* Address PR comments

1. Add a cross-file goto-def test.
2. Switch from per-message args to UserPreference.

* use arraysEqual from core

Author: sandersn

src/compiler/checker.ts

@@ -5187,7 +5187,7 @@ namespace ts {
                 function preserveCommentsOn<T extends Node>(node: T) {
                     if (some(propertySymbol.declarations, d => d.kind === SyntaxKind.JSDocPropertyTag)) {
                         const d = propertySymbol.declarations?.find(d => d.kind === SyntaxKind.JSDocPropertyTag)! as JSDocPropertyTag;
-                        const commentText = d.comment;
+                        const commentText = getTextOfJSDocComment(d.comment);
                         if (commentText) {
                             setSyntheticLeadingComments(node, [{ kind: SyntaxKind.MultiLineCommentTrivia, text: "*\n * " + commentText.replace(/\n/g, "\n * ") + "\n ", pos: -1, end: -1, hasTrailingNewLine: true }]);
                         }
@@ -6702,7 +6702,7 @@ namespace ts {
                     const typeParams = getSymbolLinks(symbol).typeParameters;
                     const typeParamDecls = map(typeParams, p => typeParameterToDeclaration(p, context));
                     const jsdocAliasDecl = symbol.declarations?.find(isJSDocTypeAlias);
-                    const commentText = jsdocAliasDecl ? jsdocAliasDecl.comment || jsdocAliasDecl.parent.comment : undefined;
+                    const commentText = getTextOfJSDocComment(jsdocAliasDecl ? jsdocAliasDecl.comment || jsdocAliasDecl.parent.comment : undefined);
                     const oldFlags = context.flags;
                     context.flags |= NodeBuilderFlags.InTypeAlias;
                     const oldEnclosingDecl = context.enclosingDeclaration;
@@ -38577,6 +38577,10 @@ namespace ts {
                 const meaning = SymbolFlags.Type | SymbolFlags.Namespace | SymbolFlags.Value;
                 return resolveEntityName(<EntityName>name, meaning, /*ignoreErrors*/ false, /*dontResolveAlias*/ true, getHostSignatureFromJSDoc(name));
             }
+            else if (isJSDocLink(name.parent)) {
+                const meaning = SymbolFlags.Type | SymbolFlags.Namespace | SymbolFlags.Value;
+                return resolveEntityName(<EntityName>name, meaning, /*ignoreErrors*/ true);
+            }
 
             if (name.parent.kind === SyntaxKind.TypePredicate) {
                 return resolveEntityName(<Identifier>name, /*meaning*/ SymbolFlags.FunctionScopedVariable);

src/compiler/emitter.ts

@@ -3565,13 +3565,16 @@ namespace ts {
         function emitJSDoc(node: JSDoc) {
             write("/**");
             if (node.comment) {
-                const lines = node.comment.split(/\r\n?|\n/g);
-                for (const line of lines) {
-                    writeLine();
-                    writeSpace();
-                    writePunctuation("*");
-                    writeSpace();
-                    write(line);
+                const text = getTextOfJSDocComment(node.comment);
+                if (text) {
+                    const lines = text.split(/\r\n?|\n/g);
+                    for (const line of lines) {
+                        writeLine();
+                        writeSpace();
+                        writePunctuation("*");
+                        writeSpace();
+                        write(line);
+                    }
                 }
             }
             if (node.tags) {
@@ -3704,10 +3707,11 @@ namespace ts {
             emit(tagName);
         }
 
-        function emitJSDocComment(comment: string | undefined) {
-            if (comment) {
+        function emitJSDocComment(comment: NodeArray<JSDocText | JSDocLink> | undefined) {
+            const text = getTextOfJSDocComment(comment);
+            if (text) {
                 writeSpace();
-                write(comment);
+                write(text);
             }
         }
 

src/compiler/factory/nodeFactory.ts

@@ -770,6 +770,10 @@ namespace ts {
         return node.kind === SyntaxKind.JSDocNameReference;
     }
 
+    export function isJSDocLink(node: Node): node is JSDocLink {
+        return node.kind === SyntaxKind.JSDocLink;
+    }
+
     export function isJSDocAllType(node: Node): node is JSDocAllType {
         return node.kind === SyntaxKind.JSDocAllType;
     }

src/compiler/factory/nodeTests.ts

@@ -896,6 +896,11 @@ namespace ts {
         return getJSDocTags(node).filter(doc => doc.kind === kind);
     }
 
+    /** Gets the text of a jsdoc comment, flattening links to their text. */
+    export function getTextOfJSDocComment(comment?: NodeArray<JSDocText | JSDocLink>) {
+        return comment?.map(c => c.kind === SyntaxKind.JSDocText ? c.text : `{@link ${c.name ? entityNameToString(c.name) + " " : ""}${c.text}}`).join("");
+    }
+
     /**
      * Gets the effective type parameters. If the node was parsed in a
      * JavaScript file, gets the type parameters from the `@template` tag from JSDoc.
@@ -1860,7 +1865,13 @@ namespace ts {
 
     /** True if node is of a kind that may contain comment text. */
     export function isJSDocCommentContainingNode(node: Node): boolean {
-        return node.kind === SyntaxKind.JSDocComment || node.kind === SyntaxKind.JSDocNamepathType || isJSDocTag(node) || isJSDocTypeLiteral(node) || isJSDocSignature(node);
+        return node.kind === SyntaxKind.JSDocComment
+            || node.kind === SyntaxKind.JSDocNamepathType
+            || node.kind === SyntaxKind.JSDocText
+            || node.kind === SyntaxKind.JSDocLink
+            || isJSDocTag(node)
+            || isJSDocTypeLiteral(node)
+            || isJSDocSignature(node);
     }
 
     // TODO: determine what this does before making it public.

src/compiler/parser.ts

@@ -1229,7 +1229,7 @@ namespace ts {
 
     /** @deprecated Use `factory.createJSDocParameterTag` or the factory supplied by your transformation context instead. */
     export const createJSDocParamTag = Debug.deprecate(function createJSDocParamTag(name: EntityName, isBracketed: boolean, typeExpression?: JSDocTypeExpression, comment?: string): JSDocParameterTag {
-        return factory.createJSDocParameterTag(/*tagName*/ undefined, name, isBracketed, typeExpression, /*isNameFirst*/ false, comment);
+        return factory.createJSDocParameterTag(/*tagName*/ undefined, name, isBracketed, typeExpression, /*isNameFirst*/ false, comment ? factory.createNodeArray([factory.createJSDocText(comment)]) : undefined);
     }, factoryDeprecation);
 
     /** @deprecated Use `factory.createComma` or the factory supplied by your transformation context instead. */
@@ -1374,4 +1374,4 @@ namespace ts {
     });
 
     // #endregion Renamed node Tests
-}
+}

src/compiler/types.ts

@@ -175,8 +175,8 @@ namespace ts.server {
                 kindModifiers: body.kindModifiers,
                 textSpan: this.decodeSpan(body, fileName),
                 displayParts: [{ kind: "text", text: body.displayString }],
-                documentation: [{ kind: "text", text: body.documentation }],
-                tags: body.tags
+                documentation: typeof body.documentation === "string" ? [{ kind: "text", text: body.documentation }] : body.documentation,
+                tags: this.decodeLinkDisplayParts(body.tags)
             };
         }
 
@@ -536,6 +536,13 @@ namespace ts.server {
                 this.lineOffsetToPosition(fileName, span.end, lineMap));
         }
 
+        private decodeLinkDisplayParts(tags: (protocol.JSDocTagInfo | JSDocTagInfo)[]): JSDocTagInfo[] {
+            return tags.map(tag => typeof tag.text === "string" ? {
+                ...tag,
+                text: [textPart(tag.text)]
+            } : (tag as JSDocTagInfo));
+        }
+
         getNameOrDottedNameSpan(_fileName: string, _startPos: number, _endPos: number): TextSpan {
             return notImplemented();
         }
@@ -554,9 +561,10 @@ namespace ts.server {
                 return undefined;
             }
 
-            const { items, applicableSpan: encodedApplicableSpan, selectedItemIndex, argumentIndex, argumentCount } = response.body;
+            const { items: encodedItems, applicableSpan: encodedApplicableSpan, selectedItemIndex, argumentIndex, argumentCount } = response.body;
 
-            const applicableSpan = this.decodeSpan(encodedApplicableSpan, fileName);
+            const applicableSpan = encodedApplicableSpan as unknown as TextSpan;
+            const items = (encodedItems as (SignatureHelpItem | protocol.SignatureHelpItem)[]).map(item => ({ ...item, tags: this.decodeLinkDisplayParts(item.tags) }));
 
             return { items, applicableSpan, selectedItemIndex, argumentIndex, argumentCount };
         }

src/compiler/utilitiesPublic.ts

@@ -1583,7 +1583,7 @@ namespace FourSlash {
             assert.equal(actualTags.length, (options.tags || ts.emptyArray).length, this.assertionMessageAtLastKnownMarker("signature help tags"));
             ts.zipWith((options.tags || ts.emptyArray), actualTags, (expectedTag, actualTag) => {
                 assert.equal(actualTag.name, expectedTag.name);
-                assert.equal(actualTag.text, expectedTag.text, this.assertionMessageAtLastKnownMarker("signature help tag " + actualTag.name));
+                assert.deepEqual(actualTag.text, expectedTag.text, this.assertionMessageAtLastKnownMarker("signature help tag " + actualTag.name));
             });
 
             const allKeys: readonly (keyof FourSlashInterface.VerifySignatureHelpOptions)[] = [