[PATCH] D134885: [Clang] Fix variant crashes from GH58028, GH57370

[Roy Jacobson via Phabricator via cfe-commits]

royjacobson created this revision.
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Fixes a null dereference in some diagnostic issuing code.

Closes https://github.com/llvm/llvm-project/issues/57370
Closes https://github.com/llvm/llvm-project/issues/58028


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D134885

Files:
  clang/lib/Sema/SemaInit.cpp
  clang/test/SemaCXX/specialization-diagnose-crash.cpp


Index: clang/test/SemaCXX/specialization-diagnose-crash.cpp
===================================================================
--- /dev/null
+++ clang/test/SemaCXX/specialization-diagnose-crash.cpp
@@ -0,0 +1,17 @@
+// RUN: %clang_cc1 -fsyntax-only %s -verify
+// expected-no-diagnostics
+// This is a reduction of GH57370 and GH58028, originally appearing
+// in libstdc++'s variant code.
+
+struct V1 {};
+struct V2 : V1 {
+  int &a;
+};
+
+template <typename T> struct X { T x; };
+
+template <class T1, class T2, class = void> struct Variant {};
+
+template <class T1, class T2> struct Variant<T1, T2, decltype(X<T2>{T1()})> {};
+
+void f() { Variant<V1, V2>(); }
Index: clang/lib/Sema/SemaInit.cpp
===================================================================
--- clang/lib/Sema/SemaInit.cpp
+++ clang/lib/Sema/SemaInit.cpp
@@ -695,10 +695,10 @@
         //   member of reference type uninitialized, the program is
         //   ill-formed.
         SemaRef.Diag(Loc, diag::err_init_reference_member_uninitialized)
-          << Field->getType()
-          << ILE->getSyntacticForm()->getSourceRange();
-        SemaRef.Diag(Field->getLocation(),
-                     diag::note_uninit_reference_member);
+            << Field->getType()
+            << (ILE->isSyntacticForm() ? ILE : ILE->getSyntacticForm())
+                   ->getSourceRange();
+        SemaRef.Diag(Field->getLocation(), diag::note_uninit_reference_member);
       }
       hadError = true;
       return;


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