Exclude variable initializers

Author: jablko

src/compiler/checker.ts

@@ -12760,8 +12760,6 @@ namespace ts {
         }
 
         function getSignatureFromDeclaration(declaration: SignatureDeclaration | JSDocSignature): Signature {
-            const signature = getSignatureOfTypeTag(declaration);
-            if (signature) return signature;
             const links = getNodeLinks(declaration);
             if (!links.resolvedSignature) {
                 const parameters: Symbol[] = [];
@@ -12941,7 +12939,15 @@ namespace ts {
                         continue;
                     }
                 }
-                result.push(getSignatureFromDeclaration(decl));
+                // If this is a function or method declaration, get the accurate minArgumentCount from the type tag, if present.
+                // If this is a variable or property declaration, apply the type tag to the target
+                // (getTypeForVariableLikeDeclaration()), not to the initializer.
+                result.push(
+                    (!isFunctionExpressionOrArrowFunction(decl) &&
+                        !isObjectLiteralMethod(decl) &&
+                        getSignatureOfTypeTag(decl)) ||
+                        getSignatureFromDeclaration(decl)
+                );
             }
             return result;
         }

tests/cases/conformance/jsdoc/checkJsdocTypeTag6.ts

@@ -21,3 +21,26 @@ function add2(a, b) { return a + b; }
 // TODO: Should be an error since signature doesn't match.
 /** @type {(a: number, b: number, c: number) => number} */
 function add3(a, b) { return a + b; }
+
+// Confirm initializers are compatible.
+// They can't have more parameters than the target.
+
+/** @type {() => void} */
+function func(more) {}
+
+/** @type {() => void} */
+const variable = function (more) {};
+
+/** @type {() => void} */
+const arrow = (more) => {};
+
+({
+  /** @type {() => void} */
+  method(more) {},
+
+  /** @type {() => void} */
+  prop: function (more) {},
+
+  /** @type {() => void} */
+  arrow: (more) => {},
+});