From aba0ef85a9b57ff9bc8e7fa2f4c19b48bdb3c0ca Mon Sep 17 00:00:00 2001
From: Gerrit Birkeland <gerrit@gerritbirkeland.com>
Date: Sat, 11 Nov 2023 14:34:50 -0700
Subject: [PATCH] Detect duplicate nodes when discovering comments

Closes #2359
Resolves #2437

Co-Authored-By: Sebastian Malton <sebastian@malton.name>
---
 CHANGELOG.md                            |  2 ++
 scripts/testcase.js                     |  6 +++++-
 src/lib/converter/comments/discovery.ts |  4 +++-
 src/lib/converter/symbols.ts            | 15 ++++++++++-----
 src/test/converter2/issues/gh2437.ts    | 18 ++++++++++++++++++
 src/test/issues.c2.test.ts              |  5 +++++
 6 files changed, 43 insertions(+), 7 deletions(-)
 create mode 100644 src/test/converter2/issues/gh2437.ts

diff --git a/CHANGELOG.md b/CHANGELOG.md
index bf4f21684..580b05317 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5,10 +5,12 @@
 -   Fixed default option values on options declared by plugins in packages mode, #2433.
 -   `gitRevision` will now be replaced in `sourceLinkTemplate`, #2434.
 -   Improved handling of function-modules created with `Object.assign`, #2436.
+-   TypeDoc will no longer warn about duplicate comments with warnings which point to a single comment, #2437
 -   Fixed an infinite loop when `skipLibCheck` is used to ignore some compiler errors, #2438.
 
 ### Thanks!
 
+-   @Nokel81
 -   @ocavue
 -   @swarnpallav
 
diff --git a/scripts/testcase.js b/scripts/testcase.js
index 0431fd2c7..64c28e729 100644
--- a/scripts/testcase.js
+++ b/scripts/testcase.js
@@ -49,7 +49,11 @@ async function main() {
     const tokens = lexer.lex(data.body);
 
     const code = /** @type {marked.marked.Tokens.Code} */ (
-        tokens.find((tok) => tok.type === "code")
+        tokens.find(
+            (tok) =>
+                tok.type === "code" &&
+                ["ts", "tsx", "js", "jsx"].includes(tok.lang || ""),
+        ) || tokens.find((tok) => tok.type === "code")
     );
     if (!code) {
         console.log("No codeblock found");
diff --git a/src/lib/converter/comments/discovery.ts b/src/lib/converter/comments/discovery.ts
index 45f085493..af3d655de 100644
--- a/src/lib/converter/comments/discovery.ts
+++ b/src/lib/converter/comments/discovery.ts
@@ -140,14 +140,16 @@ export function discoverComment(
     const reverse = !symbol.declarations?.some(ts.isSourceFile);
 
     const discovered: DiscoveredComment[] = [];
+    const seen = new Set<ts.Node>();
 
     for (const decl of symbol.declarations || []) {
         const text = decl.getSourceFile().text;
         if (wantedKinds[kind].includes(decl.kind)) {
             const node = declarationToCommentNode(decl);
-            if (!node) {
+            if (!node || seen.has(node)) {
                 continue;
             }
+            seen.add(node);
 
             // Special behavior here! We temporarily put the implementation comment
             // on the reflection which contains all the signatures. This lets us pull
diff --git a/src/lib/converter/symbols.ts b/src/lib/converter/symbols.ts
index 47705c852..be4eb0ed3 100644
--- a/src/lib/converter/symbols.ts
+++ b/src/lib/converter/symbols.ts
@@ -856,10 +856,11 @@ function convertVariable(
     exportSymbol?: ts.Symbol,
 ) {
     const declaration = symbol.getDeclarations()?.[0];
-    assert(declaration);
 
     const comment = context.getComment(symbol, ReflectionKind.Variable);
-    const type = context.checker.getTypeOfSymbolAtLocation(symbol, declaration);
+    const type = declaration
+        ? context.checker.getTypeOfSymbolAtLocation(symbol, declaration)
+        : context.checker.getTypeOfSymbol(symbol);
 
     if (
         isEnumLike(context.checker, type, declaration) &&
@@ -883,7 +884,7 @@ function convertVariable(
     );
 
     let typeNode: ts.TypeNode | undefined;
-    if (ts.isVariableDeclaration(declaration)) {
+    if (declaration && ts.isVariableDeclaration(declaration)) {
         // Otherwise we might have destructuring
         typeNode = declaration.type;
     }
@@ -902,8 +903,12 @@ function convertVariable(
     return ts.SymbolFlags.Property;
 }
 
-function isEnumLike(checker: ts.TypeChecker, type: ts.Type, location: ts.Node) {
-    if (!hasAllFlags(type.flags, ts.TypeFlags.Object)) {
+function isEnumLike(
+    checker: ts.TypeChecker,
+    type: ts.Type,
+    location?: ts.Node,
+) {
+    if (!location || !hasAllFlags(type.flags, ts.TypeFlags.Object)) {
         return false;
     }
 
diff --git a/src/test/converter2/issues/gh2437.ts b/src/test/converter2/issues/gh2437.ts
new file mode 100644
index 000000000..7525abdab
--- /dev/null
+++ b/src/test/converter2/issues/gh2437.ts
@@ -0,0 +1,18 @@
+export interface TemplatedTypeBase {
+    /**
+     * Doc here
+     */
+    prop?: string[];
+}
+
+export interface One extends TemplatedTypeBase {}
+
+export interface Two extends TemplatedTypeBase {}
+
+export type Type = One | Two;
+
+export function isTemplateInstance(
+    type: Type,
+): type is Type & { prop: string[] } {
+    return true;
+}
diff --git a/src/test/issues.c2.test.ts b/src/test/issues.c2.test.ts
index cf6558642..a97127ee4 100644
--- a/src/test/issues.c2.test.ts
+++ b/src/test/issues.c2.test.ts
@@ -1213,6 +1213,11 @@ describe("Issue Tests", () => {
         );
     });
 
+    it("Does not warn due to the diamond problem in comment discovery #2437", () => {
+        convert();
+        logger.expectNoOtherMessages();
+    });
+
     it("Handles recursive aliases without looping infinitely #2438", () => {
         const bad = query(convert(), "Bad");
         equal(bad.kind, ReflectionKind.Interface);