[AST] There is no message for C++1z-style static_assert

We would crash in the DeclPrinter trying to pretty-print the
static_assert message.  C++1z-style assertions don't have a message so
we would crash.

This fixes PR23756.

llvm-svn: 239170

1 files changed, 4 insertions, 2 deletions

diff --git a/clang/lib/AST/DeclPrinter.cpp b/clang/lib/AST/DeclPrinter.cpp
index c0f3e17693d..d8cd40ec9c6 100644
--- a/clang/lib/AST/DeclPrinter.cpp
+++ b/clang/lib/AST/DeclPrinter.cpp
@@ -733,8 +733,10 @@ void DeclPrinter::VisitImportDecl(ImportDecl *D) {
 void DeclPrinter::VisitStaticAssertDecl(StaticAssertDecl *D) {
   Out << "static_assert(";
   D->getAssertExpr()->printPretty(Out, nullptr, Policy, Indentation);
-  Out << ", ";
-  D->getMessage()->printPretty(Out, nullptr, Policy, Indentation);
+  if (StringLiteral *SL = D->getMessage()) {
+    Out << ", ";
+    SL->printPretty(Out, nullptr, Policy, Indentation);
+  }
   Out << ")";
 }