[clang] f2ea852 - Fix a crash on an invalid templated UDL declaration

[Aaron Ballman via cfe-commits]

Author: Aaron Ballman
Date: 2021-10-15T10:00:16-04:00
New Revision: f2ea85255075606563370c9249f61dfad6a3f98b

URL: https://github.com/llvm/llvm-project/commit/f2ea85255075606563370c9249f61dfad6a3f98b
DIFF: https://github.com/llvm/llvm-project/commit/f2ea85255075606563370c9249f61dfad6a3f98b.diff

LOG: Fix a crash on an invalid templated UDL declaration

We were missing a null pointer check that a template parameter existed
at all.

Added: 
    

Modified: 
    clang/lib/Sema/SemaDeclCXX.cpp
    clang/test/SemaCXX/literal-operators.cpp

Removed: 
    


################################################################################
diff  --git a/clang/lib/Sema/SemaDeclCXX.cpp b/clang/lib/Sema/SemaDeclCXX.cpp
index 31eda99089295..2d1fd1b14040f 100644
--- a/clang/lib/Sema/SemaDeclCXX.cpp
+++ b/clang/lib/Sema/SemaDeclCXX.cpp
@@ -15908,7 +15908,7 @@ checkLiteralOperatorTemplateParameterList(Sema &SemaRef,
     //
     // As a DR resolution, we also allow placeholders for deduced class
     // template specializations.
-    if (SemaRef.getLangOpts().CPlusPlus20 &&
+    if (SemaRef.getLangOpts().CPlusPlus20 && PmDecl &&
         !PmDecl->isTemplateParameterPack() &&
         (PmDecl->getType()->isRecordType() ||
          PmDecl->getType()->getAs<DeducedTemplateSpecializationType>()))

diff  --git a/clang/test/SemaCXX/literal-operators.cpp b/clang/test/SemaCXX/literal-operators.cpp
index 834d5ec7923e6..067e151606202 100644
--- a/clang/test/SemaCXX/literal-operators.cpp
+++ b/clang/test/SemaCXX/literal-operators.cpp
@@ -51,3 +51,9 @@ void test_if_2() { "foo"if; } // expected-error {{no matching literal operator f
 template<typename T> void dependent_member_template() {
   T().template operator""_foo<int>(); // expected-error {{'operator""_foo' following the 'template' keyword cannot refer to a dependent template}}
 }
+
+namespace PR51142 {
+// This code previously crashed due to a null template parameter declaration.
+template<typename T> // expected-error {{template parameter list for literal operator must be either 'char...' or 'typename T, T...'}}
+constexpr auto operator ""_l();
+}