[modules] PR20786: add (already passing) regression test from the bug report.

llvm-svn: 216683

clang/test/Modules/Inputs/PR20786/TBranchProxy.h

@@ -0,0 +1,2 @@
+#include "random.h"
+#include "TFormula.h"

clang/test/Modules/Inputs/PR20786/TFormula.h

@@ -0,0 +1 @@
+#include "TMath.h"

clang/test/Modules/Inputs/PR20786/TMath.h

@@ -0,0 +1 @@
+#include "random.h"

clang/test/Modules/Inputs/PR20786/module.modulemap

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+module TMath { header "TMath.h" }
+module TFormula { header "TFormula.h" }
+module TBranchProxy { header "TBranchProxy.h" }

clang/test/Modules/Inputs/PR20786/random.h

@@ -0,0 +1,12 @@
+namespace std {
+  template<typename> struct mersenne_twister_engine {
+    friend bool operator==(const mersenne_twister_engine &,
+                           const mersenne_twister_engine &) {
+      return false;
+    }
+  };
+  struct random_device {
+    mersenne_twister_engine<int> mt; // require complete type
+  };
+}
+

clang/test/Modules/pr20786.cpp

@@ -0,0 +1,2 @@
+// RUN: rm -rf %T
+// RUN: %clang_cc1 -fmodules -fmodules-cache-path=%T -fmodule-name=TBranchProxy -emit-module -x c++ %S/Inputs/PR20786/module.modulemap