fix(resolution): an interface overload links the implementation overload with its parameters (#2663)

CHANGELOG.md

@@ -14,6 +14,7 @@ and adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 ### Fixes
 
+- In Java, Kotlin and Scala, an interface method that is overloaded now links each overload to the implementation's overload with the same parameters, not to every implementation method of that name, so `codegraph_explore` and callers no longer follow `put(String)` into `put(List<String>, double)`. A generic interface's method still reaches every implementation of its parameter count. Thanks @hxj1225 for the report. (#2663)
 - In TypeScript, an awaited call with type arguments like `await fetchApi<User>("/me")` or `await api.get<T>(url)` now links to the function it calls. Before, the call was dropped, so typed fetch wrappers looked like they had no callers. (#2586)
 - In React, a component rendered at module scope, in a top-level constant or inside a test's `it(…)` callback, like `createRoot(el).render(<App />)` or `render(<Card />)`, now counts as rendered there, so an app's entry reaches its root component and a component's tests show among its callers. (#2587)
 - In Python, `import a.b as X` written inside a function now links its calls like `X.f()`, as the same import at module level already did. Thanks @Egrn for the report. (#2600)

__tests__/interface-impl-overloads.test.ts

@@ -0,0 +1,150 @@
+/**
+ * An interface overload is implemented by the overload with its parameters
+ * (#2663). The interface-impl synthesizer linked every overload of an
+ * interface method to every same-named overload of the implementation, so
+ * `putTairValue(String)` reached `putTairValue(List<String>, double)` and the
+ * other way round. In Java, Kotlin and Scala an override repeats the
+ * parameter list, so a base overload pairs with the implementation overloads
+ * of its parameter count, and of those with the one whose parameter types are
+ * written alike when there is one. A generic interface's `save(T)` still
+ * reaches every one-parameter `save` of its implementation.
+ *
+ * The generic case is written in Kotlin: a Java `implements Store<String>`
+ * gets no `implements` edge today, generic or not of this change.
+ */
+import { describe, it, expect, afterAll, beforeAll } from 'vitest';
+import * as fs from 'fs';
+import * as os from 'os';
+import * as path from 'path';
+import { CodeGraph } from '../src';
+
+let root = '';
+let cg: CodeGraph;
+
+beforeAll(async () => {
+  root = fs.mkdtempSync(path.join(os.tmpdir(), 'cg-iface-overloads-'));
+  const files: Record<string, string> = {
+    // The issue's example.
+    'src/ExampleService.java': `import java.util.List;
+
+interface ExampleService {
+    Object putTairValue(String tairKey);
+
+    Object putTairValue(List<String> tairKey, double count);
+}
+`,
+    'src/ExampleServiceImpl.java': `import java.util.List;
+
+class ExampleServiceImpl implements ExampleService {
+    @Override
+    public Object putTairValue(String tairKey) {
+        return null;
+    }
+
+    @Override
+    public Object putTairValue(List<String> tairKey, double count) {
+        return null;
+    }
+}
+`,
+    // Same parameter count, told apart by type, `final` and an annotation aside.
+    'src/Store.java': `interface Store {
+    void put(String key);
+    void put(int index);
+}
+
+class MapStore implements Store {
+    public void put(@Deprecated final String key) {}
+    public void put(int index) {}
+}
+`,
+    // A type parameter: no implementation's types are written alike, so every one of its count.
+    'src/Repository.kt': `interface Repository<T> {
+    fun save(entity: T)
+    fun save(entities: List<T>, flush: Boolean)
+}
+
+class UserRepository : Repository<String> {
+    override fun save(entity: String) {}
+    fun save(entities: Map<String, Int>) {}
+    override fun save(entities: List<String>, flush: Boolean) {}
+}
+`,
+    'src/Cache.kt': `interface Cache {
+    fun put(key: String): Any?
+    fun put(keys: List<String>, count: Double = 1.0): Any?
+}
+
+class MemoryCache : Cache {
+    override fun put(key: String): Any? = null
+    override fun put(keys: List<String>, count: Double): Any? = null
+}
+`,
+    'src/Repo.scala': `trait Repo {
+  def find(id: Long): Any
+  def find(ids: List[Long], limit: Int): Any
+}
+
+class SqlRepo extends Repo {
+  def find(id: Long): Any = null
+  def find(ids: List[Long], limit: Int): Any = null
+}
+`,
+  };
+  for (const [rel, content] of Object.entries(files)) {
+    fs.mkdirSync(path.dirname(path.join(root, rel)), { recursive: true });
+    fs.writeFileSync(path.join(root, rel), content);
+  }
+  cg = await CodeGraph.init(root, { index: true });
+});
+
+afterAll(() => {
+  cg?.close();
+  if (root) fs.rmSync(root, { recursive: true, force: true });
+});
+
+/** `Owner::name:line -> Owner::name:line` of every interface-impl edge from methods of `owner`. */
+const implEdges = (owner: string): string[] => {
+  const methods = cg.getNodesByKind('method').filter((n) => n.qualifiedName.startsWith(`${owner}::`));
+  return methods.flatMap((m) => cg.getOutgoingEdges(m.id)
+    .filter((e) => e.kind === 'calls' && e.metadata?.synthesizedBy === 'interface-impl')
+    .map((e) => {
+      const t = cg.getNode(e.target)!;
+      return `${m.qualifiedName}:${m.startLine} -> ${t.qualifiedName}:${t.startLine}`;
+    })).sort();
+};
+
+describe('an interface overload is implemented by the overload with its parameters (#2663)', () => {
+  it('Java: by parameter count', () => {
+    expect(implEdges('ExampleService')).toEqual([
+      'ExampleService::putTairValue:4 -> ExampleServiceImpl::putTairValue:4',
+      'ExampleService::putTairValue:6 -> ExampleServiceImpl::putTairValue:9',
+    ]);
+  });
+
+  it('Java: by parameter types at the same count', () => {
+    expect(implEdges('Store')).toEqual([
+      'Store::put:2 -> MapStore::put:7',
+      'Store::put:3 -> MapStore::put:8',
+    ]);
+  });
+
+  it('a type parameter: every implementation overload of its count, as before', () => {
+    expect(implEdges('Repository')).toEqual([
+      'Repository::save:2 -> UserRepository::save:7',
+      'Repository::save:2 -> UserRepository::save:8',
+      'Repository::save:3 -> UserRepository::save:9',
+    ]);
+  });
+
+  it('Kotlin and Scala: by parameter count, a default value aside', () => {
+    expect(implEdges('Cache')).toEqual([
+      'Cache::put:2 -> MemoryCache::put:7',
+      'Cache::put:3 -> MemoryCache::put:8',
+    ]);
+    expect(implEdges('Repo')).toEqual([
+      'Repo::find:2 -> SqlRepo::find:7',
+      'Repo::find:3 -> SqlRepo::find:8',
+    ]);
+  });
+});

src/resolution/callback-synthesizer.ts

@@ -1563,6 +1563,80 @@ function goPromotions(
   };
 }
 
+/**
+ * Languages where an override repeats the parameter list of what it
+ * overrides, so an interface overload is implemented by the same-named
+ * method with the same parameters: Java, Kotlin, C# and Scala. TypeScript is
+ * not one — an implementation may take fewer parameters than its interface
+ * declares.
+ */
+const PARAMETER_PAIRED_LANGS = new Set(['java', 'kotlin', 'csharp', 'scala']);
+
+/**
+ * The parameter types a stored method signature lists, as written and with
+ * whitespace dropped — `(String tairKey)` and `Object (List<String> tairKey,
+ * double count)` (Java), `(keys: List<String>, count: Double = 1.0): Any?`
+ * (Kotlin), `(keys: List[String], count: Double): Any` (Scala). Null when the
+ * signature is missing or takes a variable number of arguments, which a
+ * parameter count cannot pair.
+ */
+function signatureParameterTypes(signature: string | undefined): string[] | null {
+  if (!signature) return null;
+  const open = signature.indexOf('(');
+  if (open < 0) return null;
+  const params: string[] = [];
+  let depth = 0;
+  let start = open + 1;
+  for (let i = open; i < signature.length; i++) {
+    const ch = signature[i]!;
+    if (ch === '(' || ch === '<' || ch === '[' || ch === '{') depth++;
+    else if (ch === ')' || ch === '>' || ch === ']' || ch === '}') {
+      depth--;
+      if (depth === 0) {
+        params.push(signature.slice(start, i));
+        break;
+      }
+    } else if (ch === ',' && depth === 1) {
+      params.push(signature.slice(start, i));
+      start = i + 1;
+    }
+  }
+  if (depth !== 0) return null;
+  const types: string[] = [];
+  for (const raw of params) {
+    const param = raw.replace(/@\w+(?:\.\w+)*(?:\([^()]*\))?/g, '').trim();
+    if (param === '') continue;
+    if (/\.\.\.|\bvararg\b|\bparams\b|\*\s*$/.test(param)) return null;
+    const colon = param.indexOf(':');
+    const type = colon >= 0
+      ? param.slice(colon + 1).replace(/=.*$/, '')
+      : param.replace(/\bfinal\b/g, '').replace(/[A-Za-z_$][\w$]*\s*$/, '');
+    types.push(type.replace(/\s+/g, ''));
+  }
+  return types;
+}
+
+/**
+ * The implementation overloads an interface method `base` pairs with, among
+ * `impls` of its name (#2663): in Java, Kotlin, C# and Scala the ones with as
+ * many parameters as `base`, and of those the ones whose parameter types are
+ * written alike when there are any — a generic interface's `save(T entity)`
+ * is implemented as `save(User entity)`, so types that differ do not rule an
+ * overload out. Every one, as before, when a signature can't be read, takes
+ * varargs, or no overload has `base`'s parameter count.
+ */
+function pairedOverloads(base: Node, impls: Node[]): Node[] {
+  if (impls.length < 2 || !PARAMETER_PAIRED_LANGS.has(base.language)) return impls;
+  const want = signatureParameterTypes(base.signature);
+  if (!want) return impls;
+  const typed = impls.map((m) => ({ m, types: signatureParameterTypes(m.signature) }));
+  if (typed.some((t) => t.types === null)) return impls;
+  const sameArity = typed.filter((t) => t.types!.length === want.length);
+  if (sameArity.length === 0) return impls;
+  const exact = sameArity.filter((t) => t.types!.every((type, i) => type === want[i]));
+  return (exact.length > 0 ? exact : sameArity).map((t) => t.m);
+}
+
 async function interfaceOverrideEdges(queries: QueryBuilder, onYield: MaybeYield): Promise<Edge[]> {
   let scanned255 = 0;
   const edges: Edge[] = [];
@@ -1644,8 +1718,10 @@ async function interfaceOverrideEdges(queries: QueryBuilder, onYield: MaybeYield
       const promotes = goStruct && sup.provenance === 'heuristic' && base.kind === 'interface';
       // Group impl methods by name to handle OVERLOADS: an interface `list()` and
       // `list(params)` are distinct nodes and a call may resolve to either, so
-      // link every base overload → every same-name impl overload (keying by name
-      // alone would drop all but one and miss the resolved overload). A Go
+      // each base overload links the impl overloads it pairs with
+      // (pairedOverloads) — by parameters where the language makes an override
+      // repeat them, else every same-name one (keying by name alone would drop
+      // all but one and miss the resolved overload). A Go
       // interface's unexported method is matched in its own package only
       // (goMethodKey): a namesake the type declares elsewhere is another
       // method, and the one the interface asks for is promoted.
@@ -1665,7 +1741,7 @@ async function interfaceOverrideEdges(queries: QueryBuilder, onYield: MaybeYield
           if (promotes) unmatched.push(bm);
           continue;
         }
-        for (const m of impls) {
+        for (const m of pairedOverloads(bm, impls)) {
           if (added >= MAX_CALLBACKS_PER_CHANNEL) break;
           if (bm.id === m.id) continue;
           const key = `${bm.id}>${m.id}`;