[modules] Allow emission of update records for predefined __va_list_tag.

Handles the cases where old __va_list_tag is coming from a module and the new
is not, needing an update record.

Fixes https://llvm.org/bugs/show_bug.cgi?id=27890

Patch by Cristina Cristescu, Richard Smith and me.

llvm-svn: 273159

2 files changed, 10 insertions, 0 deletions

diff --git a/clang/test/Modules/Inputs/PR27890/a.h b/clang/test/Modules/Inputs/PR27890/a.h
new file mode 100644
index 00000000000..9c6e5621160
--- /dev/null
+++ b/clang/test/Modules/Inputs/PR27890/a.h
@@ -0,0 +1,9 @@
+template <class DataType> DataType values(DataType) { __builtin_va_list ValueArgs; return DataType(); }
+
+template <class DataType>
+class opt {
+public:
+  template <class Mods>
+  opt(Mods) {}
+};
+
diff --git a/clang/test/Modules/Inputs/PR27890/module.modulemap b/clang/test/Modules/Inputs/PR27890/module.modulemap
new file mode 100644
index 00000000000..85074e80789
--- /dev/null
+++ b/clang/test/Modules/Inputs/PR27890/module.modulemap
@@ -0,0 +1 @@
+module A { header "a.h" export * }