[clang] [coroutine] Create coroutine body in the correct eval context (PR #78589)

[Utkarsh Saxena via cfe-commits]

https://github.com/usx95 updated https://github.com/llvm/llvm-project/pull/78589

>From 07c6ad92fda63e69489933b5cededf8f03a68ef3 Mon Sep 17 00:00:00 2001
From: Utkarsh Saxena <usx at google.com>
Date: Thu, 18 Jan 2024 14:38:22 +0000
Subject: [PATCH 1/2] [coroutine] Create coroutine body in the correct eval
 context

---
 clang/lib/Sema/SemaCoroutine.cpp              |  4 +++
 clang/test/SemaCXX/coroutine-promise-ctor.cpp | 34 +++++++++++++++++++
 2 files changed, 38 insertions(+)
 create mode 100644 clang/test/SemaCXX/coroutine-promise-ctor.cpp

diff --git a/clang/lib/Sema/SemaCoroutine.cpp b/clang/lib/Sema/SemaCoroutine.cpp
index 0e0f8f67dcd73e1..4e600fd29ee7395 100644
--- a/clang/lib/Sema/SemaCoroutine.cpp
+++ b/clang/lib/Sema/SemaCoroutine.cpp
@@ -21,6 +21,7 @@
 #include "clang/AST/StmtCXX.h"
 #include "clang/Basic/Builtins.h"
 #include "clang/Lex/Preprocessor.h"
+#include "clang/Sema/EnterExpressionEvaluationContext.h"
 #include "clang/Sema/Initialization.h"
 #include "clang/Sema/Overload.h"
 #include "clang/Sema/ScopeInfo.h"
@@ -773,6 +774,9 @@ bool Sema::checkFinalSuspendNoThrow(const Stmt *FinalSuspend) {
 
 bool Sema::ActOnCoroutineBodyStart(Scope *SC, SourceLocation KWLoc,
                                    StringRef Keyword) {
+  // Ignore previous expr evaluation contexts.
+  EnterExpressionEvaluationContext PotentiallyEvaluated(
+      *this, Sema::ExpressionEvaluationContext::PotentiallyEvaluated);
   if (!checkCoroutineContext(*this, KWLoc, Keyword))
     return false;
   auto *ScopeInfo = getCurFunction();
diff --git a/clang/test/SemaCXX/coroutine-promise-ctor.cpp b/clang/test/SemaCXX/coroutine-promise-ctor.cpp
new file mode 100644
index 000000000000000..c8a976e838241f0
--- /dev/null
+++ b/clang/test/SemaCXX/coroutine-promise-ctor.cpp
@@ -0,0 +1,34 @@
+// RUN: %clang_cc1 -std=c++20 -ast-dump %s | FileCheck %s
+#include "Inputs/std-coroutine.h"
+
+// Github issue: https://github.com/llvm/llvm-project/issues/78290
+class Gen {
+   public:
+    class promise_type {
+       public:
+        template<typename... Args>
+        explicit promise_type(Args...) {}
+        // CHECK:       CXXConstructorDecl {{.*}} used promise_type 'void ()' {{.*}}
+        // CHECK-NEXT:     TemplateArgument pack
+        // CHECK-NEXT:     CompoundStmt {{.*}}
+        Gen get_return_object() { return {}; }
+
+        void unhandled_exception() {}
+        void return_void() {}
+        std::suspend_always await_transform(Gen gen) { return {}; }
+
+        std::suspend_always initial_suspend() { return {}; }
+        // CHECK: CXXMethodDecl {{.*}} used initial_suspend {{.*}}
+        std::suspend_always final_suspend() noexcept { return {}; }
+        // CHECK: CXXMethodDecl {{.*}} used final_suspend {{.*}}
+    };
+};
+
+Gen CoroutineBody() {
+    if constexpr (0) {
+        co_await Gen{};
+    }
+    co_await Gen{};
+}
+
+int main() { return 0; }
\ No newline at end of file

>From 4058bfbbfa37ae24d0ca044df58e8c8486440b7b Mon Sep 17 00:00:00 2001
From: Utkarsh Saxena <usx at google.com>
Date: Thu, 18 Jan 2024 14:50:52 +0000
Subject: [PATCH 2/2] new line

---
 clang/test/SemaCXX/coroutine-promise-ctor.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/clang/test/SemaCXX/coroutine-promise-ctor.cpp b/clang/test/SemaCXX/coroutine-promise-ctor.cpp
index c8a976e838241f0..787164c58be234e 100644
--- a/clang/test/SemaCXX/coroutine-promise-ctor.cpp
+++ b/clang/test/SemaCXX/coroutine-promise-ctor.cpp
@@ -31,4 +31,4 @@ Gen CoroutineBody() {
     co_await Gen{};
 }
 
-int main() { return 0; }
\ No newline at end of file
+int main() { return 0; }