[PATCH] D131423: [clang] fix frontend crash when evaluating type trait

[YingChi Long via Phabricator via cfe-commits]

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Crash input:

  template<class... Ts> bool b = __is_constructible(Ts...);
  bool x = b<>;

See https://godbolt.org/z/q39W78hsK.

Fixes https://github.com/llvm/llvm-project/issues/57008


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D131423

Files:
  clang/lib/Sema/SemaExprCXX.cpp
  clang/test/SemaCXX/type-trait-eval-crash-issue-57008.cpp


Index: clang/test/SemaCXX/type-trait-eval-crash-issue-57008.cpp
===================================================================
--- /dev/null
+++ clang/test/SemaCXX/type-trait-eval-crash-issue-57008.cpp
@@ -0,0 +1,6 @@
+// RUN: %clang_cc1 -fsyntax-only %s
+
+// Shouldn't crash here
+// Reported by https://github.com/llvm/llvm-project/issues/57008
+template<class... Ts> bool b = __is_constructible(Ts...);
+bool x = b<>;
Index: clang/lib/Sema/SemaExprCXX.cpp
===================================================================
--- clang/lib/Sema/SemaExprCXX.cpp
+++ clang/lib/Sema/SemaExprCXX.cpp
@@ -5304,6 +5304,8 @@
     //   variable t:
     //
     //     T t(create<Args>()...);
+    if (Args.empty())
+      return false;
     assert(!Args.empty());
 
     // Precondition: T and all types in the parameter pack Args shall be


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