[clang] [clang] reject to capture variable in `RequiresExprBodyDecl` (PR #78598)

[via cfe-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-clang

Author: Congcong Cai (HerrCai0907)

<details>
<summary>Changes</summary>

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

---
Full diff: https://github.com/llvm/llvm-project/pull/78598.diff


2 Files Affected:

- (modified) clang/lib/Sema/SemaExpr.cpp (+3-1) 
- (added) clang/test/SemaCXX/requires-expression-with-capture-variable.cpp (+25) 


``````````diff
diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp
index 6413a48f809ac9..767fc3787cb22f 100644
--- a/clang/lib/Sema/SemaExpr.cpp
+++ b/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())
diff --git a/clang/test/SemaCXX/requires-expression-with-capture-variable.cpp b/clang/test/SemaCXX/requires-expression-with-capture-variable.cpp
new file mode 100644
index 00000000000000..d01a54133f6c39
--- /dev/null
+++ b/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)();

``````````

</details>


https://github.com/llvm/llvm-project/pull/78598