fix(go): variables declared in a var ( … ) block are indexed

CHANGELOG.md

@@ -44,6 +44,7 @@ and adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 - In Go, a declaration's documentation is now just the comment written right above it, as `go doc` shows it. A section banner, a TODO or commented-out code that a blank line separates from a function, type, constant or variable is no longer added to the front of its documentation, or taken as its documentation when it has none of its own. Re-index Go projects after upgrading.
 - In Go, a comment directive written above a declaration, like `//go:embed static`, `//go:generate stringer -type=Kind` or `//nolint:errcheck`, is no longer part of its documentation, as `go doc` shows it, so a variable whose only comment is a `//go:embed` line no longer has that line as its description. Re-index Go projects after upgrading.
 - In Go, a constant declared inside a `const ( … )` group now keeps the doc comment written above it, like gin's `// ErrorTypeBind is used when Context.Bind() fails.`, so searching for what a constant means can find it. Before, every member of the group got the group's comment, or nothing when the group had none; a member without a comment of its own still gets the group's. Re-index Go projects after upgrading.
+- In Go, variables declared in a `var ( … )` block, like gin's `binding.JSON` or prometheus's metric counters, are now indexed, with their own doc comments. Before, every variable in such a block was missing from the graph: the calls and types in its value were not recorded, so a struct used only there looked unused, and a call made through it, like `fPointPool.Get()` or a counter's `.Inc()`, was matched by its method's name alone and could link to an unrelated type's method. Re-index Go projects after upgrading.
 - Indexing a project that includes large bundled JavaScript files, such as a copy of pdf.js or d3, is fast again: since 1.6.2, resolving the calls in a JavaScript or TypeScript file re-read the file's text above each call, so a single bundled library could add many seconds to an index. The graph it builds is unchanged. Thanks @bompus for the report. (#2334)
 - Indexing a project that ships a large minified JavaScript file, such as the GraphiQL bundle inside go-ethereum, no longer stalls at "Resolving refs" when CodeGraph runs on Node 22, and linking such a file is faster on any Node version. The graph it builds is unchanged.
 - The time `codegraph init` and `codegraph index` print beside the node and edge counts now covers the whole run, resolving references and linking included, and `codegraph sync` reports its whole run the same way. Before, it counted only reading and parsing the files, which can be a small part of an index, so a slow index looked fast. Thanks @bompus for the report. (#2334)

__tests__/fixtures/kernel-parity/torture.go

@@ -21,6 +21,13 @@ var handlerTable = map[string]func(int){
 	"recv": TargetCb,
 }
 
+// Registries: the group's comment, for a member without its own.
+var (
+	// handlersByName is documented inside its group.
+	handlersByName = map[string]func(int){"recv": TargetCb}
+	DefaultWidget  = NewRegistry()
+)
+
 // Widget is documented above its own type declaration.
 type Widget struct {
 	*Base

__tests__/go-var-groups.test.ts

@@ -0,0 +1,164 @@
+/**
+ * Variables declared in a Go `var ( … )` block were not indexed at all:
+ *
+ *   var (
+ *   	// ErrNoSides is returned for a shape without sides.
+ *   	ErrNoSides = errors.New("no sides")
+ *   	ErrTooMany = newError("too many sides")
+ *   )
+ *
+ * tree-sitter-go wraps a var group's specs in a `var_spec_list`, unlike a
+ * `const ( … )` group's, and both extractors read only the specs directly
+ * inside the declaration. So the variables had no nodes, a call in their
+ * initializers (`newError(…)`) was never recorded, and code reading them had
+ * nothing to point at. Each member is now a variable with its own doc comment
+ * (or the group's), its initializer walked under it, as a variable declared on
+ * its own already was.
+ *
+ * Runs against the native kernel (when built) and the wasm extractor, which
+ * must agree.
+ */
+import { describe, it, expect, beforeAll, beforeEach, afterEach } from 'vitest';
+import * as fs from 'fs';
+import * as path from 'path';
+import { extractFromSource } from '../src/extraction';
+import { initGrammars, loadGrammarsForLanguages } from '../src/extraction/grammars';
+import { tryKernelExtract, resetKernelForTests } from '../src/extraction/kernel';
+import type { ExtractionResult } from '../src/types';
+
+const KERNEL_PATH = path.join(
+  __dirname,
+  '..',
+  'codegraph-kernel',
+  'prebuilds',
+  `${process.platform}-${process.arch}`,
+  'codegraph-kernel.node'
+);
+const kernelAvailable = fs.existsSync(KERNEL_PATH) || process.env.CODEGRAPH_KERNEL_EXPECT === '1';
+
+const SOURCE = `// Package shapes is documented.
+package shapes
+
+import (
+	"errors"
+	"fmt"
+)
+
+// Errors returned by the shapes package.
+var (
+	// ErrNoSides is returned for a shape without sides.
+	ErrNoSides = errors.New("no sides")
+	ErrTooMany = newError("too many sides")
+)
+
+var (
+	registry = map[string]int{}
+	// DefaultName is documented inside its group.
+	DefaultName string
+)
+
+// single is documented above its own declaration.
+var single = 3
+
+func newError(msg string) error { return fmt.Errorf("shapes: %s", msg) }
+
+func check(n int) error {
+	if n == 0 {
+		return ErrNoSides
+	}
+	return ErrTooMany
+}
+`;
+
+const ENV_KEYS = ['CODEGRAPH_KERNEL', 'CODEGRAPH_KERNEL_LANGS'] as const;
+
+describe('Go variables declared in a var ( … ) block', () => {
+  let savedEnv: Record<string, string | undefined> = {};
+
+  beforeAll(async () => {
+    await initGrammars();
+    await loadGrammarsForLanguages(['go']);
+  });
+
+  beforeEach(() => {
+    savedEnv = Object.fromEntries(ENV_KEYS.map((k) => [k, process.env[k]]));
+    resetKernelForTests();
+  });
+
+  afterEach(() => {
+    for (const k of ENV_KEYS) {
+      if (savedEnv[k] === undefined) delete process.env[k];
+      else process.env[k] = savedEnv[k];
+    }
+    resetKernelForTests();
+  });
+
+  function extract(backend: 'kernel' | 'wasm', source: string): ExtractionResult {
+    if (backend === 'wasm') {
+      process.env.CODEGRAPH_KERNEL = '0';
+      return extractFromSource('shapes/shapes.go', source, 'go');
+    }
+    delete process.env.CODEGRAPH_KERNEL;
+    process.env.CODEGRAPH_KERNEL_LANGS = 'all';
+    const result = tryKernelExtract('shapes/shapes.go', source, 'go');
+    expect(result, 'kernel extraction').not.toBeNull();
+    return result!;
+  }
+
+  const backends = kernelAvailable ? (['kernel', 'wasm'] as const) : (['wasm'] as const);
+
+  for (const crlf of [false, true]) {
+    it.each(backends)(`%s${crlf ? ' (CRLF)' : ''}`, (backend) => {
+      const result = extract(backend, crlf ? SOURCE.replace(/\n/g, '\r\n') : SOURCE);
+      const byName = new Map(result.nodes.map((n) => [`${n.kind} ${n.name}`, n]));
+      const node = (kind: string, name: string) => {
+        const found = byName.get(`${kind} ${name}`);
+        expect(found, `${kind} ${name}`).toBeDefined();
+        return found!;
+      };
+      const file = result.nodes.find((n) => n.kind === 'file')!;
+
+      // Every member of a var group is a variable the file contains, with its
+      // own doc comment, or the group's when it has none.
+      const docs = Object.fromEntries(
+        ['ErrNoSides', 'ErrTooMany', 'registry', 'DefaultName', 'single'].map((name) => [
+          name,
+          node('variable', name).docstring ?? null,
+        ])
+      );
+      expect(docs).toEqual({
+        ErrNoSides: 'ErrNoSides is returned for a shape without sides.',
+        ErrTooMany: 'Errors returned by the shapes package.',
+        registry: null,
+        DefaultName: 'DefaultName is documented inside its group.',
+        single: 'single is documented above its own declaration.',
+      });
+      for (const name of ['ErrNoSides', 'ErrTooMany', 'registry', 'DefaultName']) {
+        const id = node('variable', name).id;
+        expect(
+          result.edges.some((e) => e.kind === 'contains' && e.source === file.id && e.target === id),
+          `file contains ${name}`
+        ).toBe(true);
+      }
+
+      // A call in a member's initializer is that variable's.
+      const tooMany = node('variable', 'ErrTooMany').id;
+      expect(
+        result.unresolvedReferences.some(
+          (r) => r.fromNodeId === tooMany && r.referenceKind === 'calls' && r.referenceName === 'newError'
+        ),
+        'ErrTooMany calls newError'
+      ).toBe(true);
+
+      // Code reading a member in the same file references it.
+      const check = node('function', 'check').id;
+      for (const name of ['ErrNoSides', 'ErrTooMany']) {
+        const id = node('variable', name).id;
+        expect(
+          result.edges.some((e) => e.kind === 'references' && e.source === check && e.target === id),
+          `check references ${name}`
+        ).toBe(true);
+      }
+    });
+  }
+});

codegraph-kernel/src/go.rs

@@ -682,8 +682,18 @@ impl<'t> Walker<'t> {
         let docstring = self.docstring_of(node);
         let is_const_decl = node.kind() == "const_declaration";
 
+        // A `var ( … )` group wraps its specs in a `var_spec_list`; a
+        // `const ( … )` group holds them directly.
+        let mut specs: Vec<Node<'t>> = Vec::new();
         for i in 0..node.named_child_count() {
-            let Some(spec) = node.named_child(i) else { continue };
+            let Some(child) = node.named_child(i) else { continue };
+            if child.kind() == "var_spec_list" {
+                specs.extend((0..child.named_child_count()).filter_map(|j| child.named_child(j)));
+            } else {
+                specs.push(child);
+            }
+        }
+        for spec in specs {
             if !matches!(spec.kind(), "var_spec" | "const_spec") {
                 continue;
             }
@@ -697,9 +707,9 @@ impl<'t> Walker<'t> {
                         None
                     };
                     let signature = value_node.map(|v| util::init_signature(self.text(v)));
-                    // A member of a `const ( … )` group has its own doc
-                    // comment beside it in the parentheses; one without keeps
-                    // the group's.
+                    // A member of a `const ( … )` or `var ( … )` group has its
+                    // own doc comment beside it in the parentheses; one without
+                    // keeps the group's.
                     let doc = self.docstring_of(spec).or_else(|| docstring.clone());
                     var_row = self.create_node(
                         if is_const_decl { "constant" } else { "variable" },

src/extraction/tree-sitter.ts

@@ -3558,10 +3558,12 @@ export class TreeSitterExtractor {
       }
     } else if (this.language === 'go') {
       // Go: var_declaration, short_var_declaration, const_declaration
-      // These can have multiple identifiers on the left
-      const specs = node.namedChildren.filter(c =>
-        c.type === 'var_spec' || c.type === 'const_spec'
-      );
+      // These can have multiple identifiers on the left. A `var ( … )` group
+      // wraps its specs in a `var_spec_list`; a `const ( … )` group holds them
+      // directly.
+      const specs = node.namedChildren
+        .flatMap((c) => (c.type === 'var_spec_list' ? c.namedChildren : [c]))
+        .filter((c) => c.type === 'var_spec' || c.type === 'const_spec');
 
       for (const spec of specs) {
         const nameNode = spec.namedChild(0);
@@ -3572,8 +3574,8 @@ export class TreeSitterExtractor {
           const initValue = valueNode ? getNodeText(valueNode, this.source).slice(0, 100) : undefined;
           const initSignature = initValue ? `= ${initValue}${initValue.length >= 100 ? '...' : ''}` : undefined;
 
-          // A member of a `const ( … )` group has its own doc comment beside
-          // it in the parentheses; one without keeps the group's.
+          // A member of a `const ( … )` or `var ( … )` group has its own doc
+          // comment beside it in the parentheses; one without keeps the group's.
           varNode = this.createNode(node.type === 'const_declaration' ? 'constant' : 'variable', name, spec, {
             docstring: this.docstringFor(spec) ?? docstring,
             signature: initSignature,