diff --git a/CHANGELOG.md b/CHANGELOG.md
index 1f354ff0..58371fc6 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -14,6 +14,7 @@ and adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 ### Fixes
 
+- C++ classes written around macros and preprocessor conditionals now keep their members. These include an access specifier spelled as a macro (`JSON_PRIVATE_UNLESS_TESTED:`), an attribute macro after a template head or a doc comment, and an `#if` in the middle of a declaration, such as inside a constructor's initializer list. The first branch of a mid-declaration `#if` is the one indexed. nlohmann/json's `basic_json` class used to be lost whole and now has its roughly 390 members. Files with a parse error dropped on redis, curl, pybind11 and leveldb, and no file got worse. Re-index after upgrading.
 - Kotlin files using newer syntax now keep their classes intact. That covers `when` guard conditions (`is X if cond ->`), `..<` ranges, multi-dollar strings (`$$"…"`) and nullable receivers in function types (`T?.() -> R`). Before, the class around such code could come out as a scatter of loose functions. On Exposed, files with a parse error dropped from 65 to 43, and on kotlinx.coroutines from 50 to 46. Re-index after upgrading.
 - A call through a class name, like `THorse.Get(…)`, `MyView.as_view()` or `ColorChoices.values()`, now reaches the class method that class inherits. The inheritance is read from the class declarations themselves, in Pascal, Python, Ruby, PHP, TypeScript/JavaScript and the Java family. Before, such a call was resolved by guessing from the name. On Horse, `THorse.Get('/ping', …)` used to land on a route-group interface's `Get` 120 times. Re-index after upgrading.
 - In Objective-C, `[super init]` and other messages to `super` now reach the superclass's method, never the sending class's own override. This also works where the index lost the `@implementation`'s range. On SDWebImage, `NSObject` subclasses' `[super init]` used to land on `SDDiskCache`'s `init`, and `[self class]` in tests on a proxy class's `class`. On AFNetworking, a serializer's `[super encodeWithCoder:]` now reaches its superclass. Re-index after upgrading.
diff --git a/__tests__/cpp-conditional-class.test.ts b/__tests__/cpp-conditional-class.test.ts
new file mode 100644
index 00000000..69c690b6
--- /dev/null
+++ b/__tests__/cpp-conditional-class.test.ts
@@ -0,0 +1,118 @@
+/**
+ * nlohmann/json's `basic_json` — the class most C++ projects vendor — was lost
+ * whole: tree-sitter-cpp cannot read
+ *
+ * - an access specifier spelled as a macro (`JSON_PRIVATE_UNLESS_TESTED:`),
+ * - a lone attribute macro after a template head or after a `/// @sa
+ *   https://…/` doc comment (both ends looked like an operator continuing the
+ *   line, so the macro wasn't blanked),
+ * - a preprocessor conditional in the middle of a declaration: inside a
+ *   member-initializer list, or between a template head and its function.
+ *
+ * The macros are rewritten or blanked, and a mid-declaration conditional keeps
+ * its first branch (directives and later branches blanked, offsets intact).
+ * An enum member after `A, /* comment *\/` is still an enum member.
+ */
+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';
+import { blankLoneMacroLines, flattenMidStatementConditionals } from '../src/extraction/languages/c-cpp';
+
+const HEADER = `#pragma once
+#define JSON_PRIVATE_UNLESS_TESTED private
+#define JSON_HEDLEY_RETURNS_NON_NULL
+#define JSON_HEDLEY_WARN_UNUSED_RESULT
+
+template<typename T>
+class basic_json
+{
+  JSON_PRIVATE_UNLESS_TESTED:
+    using lexer = int;
+
+    template<typename U, typename... Args>
+    JSON_HEDLEY_RETURNS_NON_NULL
+    static U* create(Args&& ... args)
+    {
+        return nullptr;
+    }
+
+    class nesting_depth_guard
+    {
+      public:
+        nesting_depth_guard() noexcept
+#ifdef JSON_NO_THREAD_LOCAL
+            : m_okay(false)
+#else
+            : m_okay(depth() < 10)
+#endif
+        {
+        }
+      private:
+        bool m_okay;
+    };
+
+  public:
+    /// @brief returns version information on the library
+    /// @sa https://json.nlohmann.me/api/basic_json/meta/
+    JSON_HEDLEY_WARN_UNUSED_RESULT
+    static basic_json meta()
+    {
+        return basic_json();
+    }
+
+    template < typename ValueType >
+#if defined(JSON_HAS_CPP_14)
+    constexpr
+#endif
+    auto get() const -> ValueType
+    {
+        return ValueType();
+    }
+
+    void dump() const {}
+};
+`;
+
+let root = '';
+let cg: CodeGraph;
+
+beforeAll(async () => {
+  root = fs.mkdtempSync(path.join(os.tmpdir(), 'cg-cpp-conditional-'));
+  fs.mkdirSync(path.join(root, 'include'), { recursive: true });
+  fs.writeFileSync(path.join(root, 'include/json.hpp'), HEADER);
+  cg = await CodeGraph.init(root, { index: true });
+});
+
+afterAll(() => {
+  cg?.close();
+  if (root) fs.rmSync(root, { recursive: true, force: true });
+});
+
+describe('a C++ class written around macros and conditionals', () => {
+  it('keeps its members', () => {
+    const members = cg.getNodesInFile('include/json.hpp')
+      .filter((n) => n.qualifiedName.startsWith('basic_json::') && (n.kind === 'method' || n.kind === 'class'))
+      .map((n) => n.name)
+      .sort();
+    expect(members).toEqual(expect.arrayContaining(['create', 'dump', 'get', 'meta', 'nesting_depth_guard']));
+  });
+
+  it('keeps the first branch of a mid-declaration conditional, offsets intact', () => {
+    const src = 'A() noexcept\n#ifdef X\n  : a(1)\n#else\n  : a(2)\n#endif\n{}\n';
+    const out = flattenMidStatementConditionals(src);
+    expect(out.length).toBe(src.length);
+    expect(out).toContain('  : a(1)');
+    expect(out).not.toContain('a(2)');
+    expect(out).not.toContain('#');
+    // Between whole declarations a conditional stays.
+    const top = 'int a;\n#ifdef X\nint b;\n#endif\n';
+    expect(flattenMidStatementConditionals(top)).toBe(top);
+  });
+
+  it('does not blank an enum member after a commented line', () => {
+    const src = 'typedef enum {\n  CURLE_OK,\n  CURLE_TOO_LARGE, /* 100 */\n  CURL_LAST /* never use! */\n} CURLcode;\n';
+    expect(blankLoneMacroLines(src)).toBe(src);
+  });
+});
diff --git a/src/extraction/languages/c-cpp.ts b/src/extraction/languages/c-cpp.ts
index c4aa31a4..ac238978 100644
--- a/src/extraction/languages/c-cpp.ts
+++ b/src/extraction/languages/c-cpp.ts
@@ -701,7 +701,14 @@ export function blankLoneMacroLines(source: string): string {
     if (!(m[1] as string).includes('_')) continue;
     let prev = i - 1;
     while (prev >= 0 && content(lines[prev] as string) === '') prev--;
-    if (prev >= 0 && LONE_MACRO_CONTINUATION_END_RE.test(content(lines[prev] as string))) continue;
+    // Judged on the line's code: a comment — `/// @sa https://…/meta/`, a
+    // block comment's `*/` — ends in whatever it likes but continues nothing,
+    // while `CURLE_TOO_LARGE, /* 100 */` continues with its comma. A template
+    // head (`template<typename T, typename... Args>`) before a declaration
+    // continues nothing either.
+    const prevText = prev >= 0 ? content(lines[prev] as string) : '';
+    const prevCode = /^(?:\/\/|\/\*|\*)/.test(prevText) ? '' : prevText.replace(/\/\*.*?\*\/|\/\/.*$/g, '').trim();
+    if (prevCode !== '' && !/^template\s*</.test(prevCode) && LONE_MACRO_CONTINUATION_END_RE.test(prevCode)) continue;
     let next = i + 1;
     while (next < lines.length && content(lines[next] as string) === '') next++;
     if (next < lines.length) {
@@ -953,9 +960,109 @@ function normalizeCppComInterfaces(source: string): string {
  * annotations, and CUDA specifiers + launch syntax (by `.cu`/`.cuh` extension
  * or by content, for CUDA living in `.h`/`.hpp` headers). Offset-preserving;
  * directive lines are restored at the end (see restoreDirectiveLines). */
+/**
+ * An access specifier spelled as a macro — nlohmann/json's
+ * `JSON_PRIVATE_UNLESS_TESTED:` (private, or public under test), Qt's
+ * `Q_SIGNALS:` — is rewritten to the keyword it stands for, padded to the
+ * same length. tree-sitter-cpp reads `NAME:` inside a class as an error, and
+ * json.hpp's recovery lost members around each one.
+ */
+const ACCESS_MACRO_LINE = /^([ \t]*)([A-Z][A-Z0-9]*_[A-Z0-9_]*)([ \t]*):(?!:)(?=[ \t]*(?:\/\/[^\n]*)?\r?$)/gm;
+export function rewriteCppAccessMacros(source: string): string {
+  if (!/_[A-Z0-9_]*[ \t]*:(?!:)/.test(source)) return source;
+  return source.replace(ACCESS_MACRO_LINE, (m, indent: string, name: string, gap: string) => {
+    const keyword = /PRIVATE/.test(name) ? 'private' : /PROTECTED/.test(name) ? 'protected'
+      : /PUBLIC|^Q_SIGNALS$|^Q_SLOTS$/.test(name) ? 'public' : null;
+    if (!keyword || keyword.length > name.length + gap.length) return m;
+    return `${indent}${keyword}${' '.repeat(name.length + gap.length - keyword.length)}:`;
+  });
+}
+
+/**
+ * A preprocessor conditional in the middle of a declaration or expression —
+ * inside a constructor's member-initializer list (nlohmann/json's
+ * `noexcept\n#ifdef JSON_NO_THREAD_LOCAL\n : m_okay(false)\n#else\n :
+ * m_okay(…)\n#endif`), between a template head and its function
+ * (`template <…>\n#if defined(JSON_HAS_CPP_14)\n constexpr\n#endif\n auto
+ * get()`), inside an argument list — is an error to tree-sitter-cpp, and
+ * json.hpp's recovery took the whole `basic_json` class with it. Where the
+ * code before the `#if` has not ended a statement or declaration (`;`, `{`,
+ * `}`, a label's `:`), its directives are blanked and so is every branch
+ * after the first: one consistent configuration, every newline and offset
+ * kept. A conditional between whole declarations is left alone.
+ */
+export function flattenMidStatementConditionals(source: string): string {
+  if (!source.includes('#')) return source;
+  const lines = source.split('\n');
+  const directive = (i: number) => /^[ \t]*#[ \t]*(\w+)/.exec(lines[i] ?? '')?.[1] ?? null;
+  const code = (i: number) => (lines[i] ?? '').replace(/\/\/.*$/, '').replace(/\/\*.*?\*\//g, '').trim();
+  let changed = false;
+  const blank = (i: number) => {
+    lines[i] = (lines[i] ?? '').replace(/[^\r]/g, ' ');
+    changed = true;
+  };
+  let lastCode = '';          // the last non-directive code line, trimmed
+  let inBlockComment = false;
+  let region = 0;             // #if depth inside a flattened conditional (0 = none)
+  let skipFrom = 0;           // the depth whose later branches are blanked (0 = none)
+  let continued = false;      // inside a `\`-continued directive (a multi-line #define)
+  for (let i = 0; i < lines.length; i++) {
+    if (continued) {
+      continued = /\\\s*$/.test(lines[i] ?? '');
+      continue;
+    }
+    const d = directive(i);
+    if (d !== null && !inBlockComment) {
+      // A directive continued with `\` spans lines; its body is not code.
+      if (/\\\s*$/.test(lines[i]!)) {
+        continued = true;
+        if (region === 0) continue;
+      }
+      const opens = /^if/.test(d);
+      if (region === 0) {
+        // Not after a statement macro written without its `;`
+        // (`RAPIDJSON_DIAG_OFF(padded)`), either.
+        const mid = opens && lastCode !== '' && !/[;{}]$|^[\w\s]*:$|\*\/$/.test(lastCode) &&
+          !/^(?:public|private|protected)\s*:$/.test(lastCode) && !/^[A-Z][A-Z0-9_]*(?:\s*\(.*\))?$/.test(lastCode);
+        if (!mid) continue;
+        region = 1;
+        blank(i);
+        continue;
+      }
+      if (opens) region++;
+      else if ((d === 'else' || d === 'elif') && skipFrom === 0) skipFrom = region;
+      else if (d === 'endif') {
+        if (skipFrom === region) skipFrom = 0;
+        region--;
+      }
+      if (/^(?:if|ifdef|ifndef|else|elif|elifdef|elifndef|endif)$/.test(d)) blank(i);
+      continue;
+    }
+    const text = lines[i] ?? '';
+    if (region > 0 && skipFrom > 0) {
+      if (text.trim() !== '') blank(i);
+      continue;
+    }
+    // Track block comments so a `#` or `;` inside one is not read as code.
+    const trimmed = code(i);
+    if (inBlockComment) {
+      if (text.includes('*/')) inBlockComment = false;
+      continue;
+    }
+    if (/\/\*(?!.*\*\/)/.test(text.replace(/\/\/.*$/, ''))) {
+      inBlockComment = true;
+      const before = trimmed.split('/*')[0]!.trim();
+      if (before !== '') lastCode = before;
+      continue;
+    }
+    if (trimmed !== '') lastCode = trimmed;
+  }
+  return changed ? lines.join('\n') : source;
+}
+
 function preParseCppSource(source: string, filePath?: string): string {
   const rawStrings = maskCppRawStrings(source);
-  source = rawStrings.source;
+  source = flattenMidStatementConditionals(rewriteCppAccessMacros(rawStrings.source));
   // blankCLeadingAttrMacros runs AFTER the api-prefix blank so a stacked
   // `FMT_NORETURN FMT_API void f(…)` reduces to the `MACRO Ret name(` shape
   // it matches (the _API token is already spaces by then).