From: Eric Fiselier <eric@efcs.ca>
Date: Fri, 30 Sep 2016 22:38:31 +0000 (+0000)
Subject: [coroutines] Diagnose when 'main' is declared as a coroutine.
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=fa5a2d7a669a54f6ed90d6026a1ad25ed6cd6649;p=clang

[coroutines] Diagnose when 'main' is declared as a coroutine.

Summary: The title says it all.

Reviewers: rsmith, GorNishanov

Subscribers: mehdi_amini, cfe-commits

Differential Revision: https://reviews.llvm.org/D25078

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@282973 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/include/clang/Basic/DiagnosticSemaKinds.td b/include/clang/Basic/DiagnosticSemaKinds.td
index 00b9ca805a..58e8e00d85 100644
--- a/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/include/clang/Basic/DiagnosticSemaKinds.td
@@ -8562,6 +8562,8 @@ def err_coroutine_ctor_dtor : Error<
   "'%1' cannot be used in a %select{constructor|destructor}0">;
 def err_coroutine_constexpr : Error<
   "'%0' cannot be used in a constexpr function">;
+def err_coroutine_main : Error<
+  "'main' cannot be a coroutine">;
 def err_coroutine_varargs : Error<
   "'%0' cannot be used in a varargs function">;
 def ext_coroutine_without_co_await_co_yield : ExtWarn<
diff --git a/lib/Sema/SemaCoroutine.cpp b/lib/Sema/SemaCoroutine.cpp
index 5143036088..461ca8eddc 100644
--- a/lib/Sema/SemaCoroutine.cpp
+++ b/lib/Sema/SemaCoroutine.cpp
@@ -127,6 +127,11 @@ checkCoroutineContext(Sema &S, SourceLocation Loc, StringRef Keyword) {
     S.Diag(Loc, diag::err_coroutine_constexpr) << Keyword;
   } else if (FD->isVariadic()) {
     S.Diag(Loc, diag::err_coroutine_varargs) << Keyword;
+  } else if (FD->isMain()) {
+    S.Diag(FD->getLocStart(), diag::err_coroutine_main);
+    S.Diag(Loc, diag::note_declared_coroutine_here)
+      << (Keyword == "co_await" ? 0 :
+          Keyword == "co_yield" ? 1 : 2);
   } else {
     auto *ScopeInfo = S.getCurFunction();
     assert(ScopeInfo && "missing function scope for function");
diff --git a/test/SemaCXX/coroutines.cpp b/test/SemaCXX/coroutines.cpp
index d375e9eddb..92fdc79474 100644
--- a/test/SemaCXX/coroutines.cpp
+++ b/test/SemaCXX/coroutines.cpp
@@ -283,3 +283,11 @@ struct bad_promise_5 {
 coro<bad_promise_5> bad_final_suspend() { // expected-error {{no member named 'await_ready' in 'not_awaitable'}}
   co_await a;
 }
+
+
+template<> struct std::coroutine_traits<int, int, const char**>
+{ using promise_type = promise; };
+
+int main(int, const char**) { // expected-error {{'main' cannot be a coroutine}}
+  co_await a; // expected-note {{function is a coroutine due to use of 'co_await' here}}
+}