Use pointer-by-value captures in coroutine test lambdas

Defense-in-depth against a GCC 14 bug where reference captures in
coroutine lambdas are corrupted in the coroutine frame. The root
cause is fixed in CoroTaskRunner::init() (heap storage), but using
explicit pointer captures avoids any residual risk.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: pratikmankawde

src/test/core/Coroutine_test.cpp

@@ -40,6 +40,11 @@ class Coroutine_test : public beast::unit_test::suite
         }
     };
 
+    // NOTE: All coroutine lambdas passed to postCoroTask use explicit
+    // pointer-by-value captures instead of [&] to work around a GCC 14
+    // bug where reference captures in coroutine lambdas are corrupted
+    // in the coroutine frame.
+
     void
     correct_order()
     {
@@ -56,11 +61,11 @@ class Coroutine_test : public beast::unit_test::suite
         gate g1, g2;
         std::shared_ptr<JobQueue::CoroTaskRunner> c;
         env.app().getJobQueue().postCoroTask(
-            jtCLIENT, "CoroTest", [&](auto runner) -> CoroTask<void> {
-                c = runner;
-                g1.signal();
+            jtCLIENT, "CoroTest", [cp = &c, g1p = &g1, g2p = &g2](auto runner) -> CoroTask<void> {
+                *cp = runner;
+                g1p->signal();
                 co_await runner->suspend();
-                g2.signal();
+                g2p->signal();
                 co_return;
             });
         BEAST_EXPECT(g1.wait_for(5s));
@@ -84,14 +89,14 @@ class Coroutine_test : public beast::unit_test::suite
 
         gate g;
         env.app().getJobQueue().postCoroTask(
-            jtCLIENT, "CoroTest", [&](auto runner) -> CoroTask<void> {
+            jtCLIENT, "CoroTest", [gp = &g](auto runner) -> CoroTask<void> {
                 // Schedule a resume before suspending.  The posted job
                 // cannot actually call resume() until the current resume()
                 // releases CoroTaskRunner::mutex_, which only happens after
                 // the coroutine suspends at co_await.
                 runner->post();
                 co_await runner->suspend();
-                g.signal();
+                gp->signal();
                 co_return;
             });
         BEAST_EXPECT(g.wait_for(5s));
@@ -126,20 +131,23 @@ class Coroutine_test : public beast::unit_test::suite
 
         for (int i = 0; i < N; ++i)
         {
-            jq.postCoroTask(jtCLIENT, "CoroTest", [&, id = i](auto runner) -> CoroTask<void> {
-                a[id] = runner;
-                g.signal();
-                co_await runner->suspend();
-
-                this->BEAST_EXPECT(*lv == -1);
-                *lv = id;
-                this->BEAST_EXPECT(*lv == id);
-                g.signal();
-                co_await runner->suspend();
-
-                this->BEAST_EXPECT(*lv == id);
-                co_return;
-            });
+            jq.postCoroTask(
+                jtCLIENT,
+                "CoroTest",
+                [this, ap = &a, gp = &g, lvp = &lv, id = i](auto runner) -> CoroTask<void> {
+                    (*ap)[id] = runner;
+                    gp->signal();
+                    co_await runner->suspend();
+
+                    this->BEAST_EXPECT(**lvp == -1);
+                    **lvp = id;
+                    this->BEAST_EXPECT(**lvp == id);
+                    gp->signal();
+                    co_await runner->suspend();
+
+                    this->BEAST_EXPECT(**lvp == id);
+                    co_return;
+                });
             BEAST_EXPECT(g.wait_for(5s));
             a[i]->join();
         }

src/test/core/JobQueue_test.cpp

@@ -43,6 +43,11 @@ class JobQueue_test : public beast::unit_test::suite
         }
     }
 
+    // NOTE: All coroutine lambdas passed to postCoroTask use explicit
+    // pointer-by-value captures instead of [&] to work around a GCC 14
+    // bug where reference captures in coroutine lambdas are corrupted
+    // in the coroutine frame.
+
     void
     testPostCoroTask()
     {
@@ -53,8 +58,8 @@ class JobQueue_test : public beast::unit_test::suite
             // Test repeated post()s until the coroutine completes.
             std::atomic<int> yieldCount{0};
             auto const runner = jQueue.postCoroTask(
-                jtCLIENT, "PostCoroTest1", [&yieldCount](auto runner) -> CoroTask<void> {
-                    while (++yieldCount < 4)
+                jtCLIENT, "PostCoroTest1", [ycp = &yieldCount](auto runner) -> CoroTask<void> {
+                    while (++(*ycp) < 4)
                         co_await runner->suspend();
                     co_return;
                 });
@@ -81,8 +86,8 @@ class JobQueue_test : public beast::unit_test::suite
             // Test repeated resume()s until the coroutine completes.
             int yieldCount{0};
             auto const runner = jQueue.postCoroTask(
-                jtCLIENT, "PostCoroTest2", [&yieldCount](auto runner) -> CoroTask<void> {
-                    while (++yieldCount < 4)
+                jtCLIENT, "PostCoroTest2", [ycp = &yieldCount](auto runner) -> CoroTask<void> {
+                    while (++(*ycp) < 4)
                         co_await runner->suspend();
                     co_return;
                 });
@@ -118,8 +123,8 @@ class JobQueue_test : public beast::unit_test::suite
             // Not recommended for the faint of heart...
             bool unprotected;
             auto const runner = jQueue.postCoroTask(
-                jtCLIENT, "PostCoroTest3", [&unprotected](auto) -> CoroTask<void> {
-                    unprotected = false;
+                jtCLIENT, "PostCoroTest3", [up = &unprotected](auto) -> CoroTask<void> {
+                    *up = false;
                     co_return;
                 });
             BEAST_EXPECT(runner == nullptr);