[clang] reject to capture variable in RequiresExprBodyDecl

Expression in `RequiresExprBodyDecl` is resolved as constants and should not be captured.
Fixes: #69307, #76593.

Author: HerrCai0907

clang/lib/Sema/SemaExpr.cpp

@@ -19719,7 +19719,9 @@ bool Sema::tryCaptureVariable(
   // we can bailout early.
   if (CapturingFunctionScopes == 0 && (!BuildAndDiagnose || VarDC == DC))
     return true;
-
+  // Expression in `RequiresExprBodyDecl` should not be captured.
+  if (isa<RequiresExprBodyDecl>(CurContext))
+    return true;
   const auto *VD = dyn_cast<VarDecl>(Var);
   if (VD) {
     if (VD->isInitCapture())

clang/test/SemaCXX/requires-expression-with-capture-variable.cpp

@@ -0,0 +1,25 @@
+// RUN: %clang -fsyntax-only -std=c++20 -Xclang -verify %s
+
+// expected-no-diagnostics
+
+auto GH69307_Func_1() {
+  constexpr auto b = 1;
+  return [&](auto c) -> int
+           requires requires { b + c; }
+  { return 1; };
+};
+auto GH69307_Func_Ret = GH69307_Func_1()(1);
+
+auto GH69307_Lambda_1 = []() {
+  return [&](auto c) -> int
+           requires requires { c; }
+  { return 1; };
+};
+auto GH69307_Lambda_1_Ret = GH69307_Lambda_1()(1);
+
+auto GH69307_Lambda_2 = [](auto c) {
+  return [&]() -> int
+           requires requires { c; }
+  { return 1; };
+};
+auto GH69307_Lambda_2_Ret = GH69307_Lambda_2(1)();