[clang] [Clang][SemaCXX] improve sema check of clang::musttail attribute (PR #77727)

[Qizhi Hu via cfe-commits]

https://github.com/jcsxky created https://github.com/llvm/llvm-project/pull/77727

Call function with no-return attribute generate code with unreachable instruction instead of return and if the call  statement  has  `clang::musttail` attribute, it would crash in Verify. Check this condition in Sema.

>From 0a340a46a69f04555bfeaeb14f214f57ebd6b9cd Mon Sep 17 00:00:00 2001
From: huqizhi <huqizhi at feysh.com>
Date: Thu, 11 Jan 2024 13:02:21 +0800
Subject: [PATCH] [Clang][SemaCXX] improve sema check of clang::musttail
 attribute

---
 clang/include/clang/Basic/DiagnosticSemaKinds.td | 2 ++
 clang/lib/Sema/SemaStmt.cpp                      | 6 ++++++
 clang/test/SemaCXX/PR76631.cpp                   | 7 +++++++
 3 files changed, 15 insertions(+)
 create mode 100644 clang/test/SemaCXX/PR76631.cpp

diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td b/clang/include/clang/Basic/DiagnosticSemaKinds.td
index 3884dca59e2f3b..b40befc5c1cfb5 100644
--- a/clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -3113,6 +3113,8 @@ def err_musttail_scope : Error<
   "cannot perform a tail call from this return statement">;
 def err_musttail_no_variadic : Error<
   "%0 attribute may not be used with variadic functions">;
+def err_musttail_no_return : Error<
+  "%0 attribute may not be used with no-return-attribute functions">;
 
 def err_nsobject_attribute : Error<
   "'NSObject' attribute is for pointer types only">;
diff --git a/clang/lib/Sema/SemaStmt.cpp b/clang/lib/Sema/SemaStmt.cpp
index 21efe25ed84a3d..9e7c8c7e4e8c12 100644
--- a/clang/lib/Sema/SemaStmt.cpp
+++ b/clang/lib/Sema/SemaStmt.cpp
@@ -786,6 +786,12 @@ bool Sema::checkMustTailAttr(const Stmt *St, const Attr &MTA) {
     return false;
   }
 
+  const auto *CalleeDecl = CE->getCalleeDecl();
+  if (CalleeDecl && CalleeDecl->hasAttr<CXX11NoReturnAttr>()) {
+    Diag(St->getBeginLoc(), diag::err_musttail_no_return) << &MTA;
+    return false;
+  }
+
   // Caller and callee must match in whether they have a "this" parameter.
   if (CallerType.This.isNull() != CalleeType.This.isNull()) {
     if (const auto *ND = dyn_cast_or_null<NamedDecl>(CE->getCalleeDecl())) {
diff --git a/clang/test/SemaCXX/PR76631.cpp b/clang/test/SemaCXX/PR76631.cpp
new file mode 100644
index 00000000000000..df89753bd12580
--- /dev/null
+++ b/clang/test/SemaCXX/PR76631.cpp
@@ -0,0 +1,7 @@
+[[noreturn]] void throw_int() {
+  throw int();
+}
+
+void throw_int_wrapper() {
+  [[clang::musttail]] return throw_int(); // expected-error {{'musttail' attribute may not be used with no-return-attribute functions}}
+}