dsymutil: Avoid pruning non-type forward declarations inside DW_TAG_module

forward declarations.

Especially with template instantiations, there are legitimate reasons
why for declarations might be emitted into a DW_TAG_module skeleton /
forward-declaration sub-tree, that are not forward declarations in the
sense of that there is a more complete definition over in a .pcm file.

The example in the testcase is a constant DW_TAG_member of a
DW_TAG_class template instatiation.

rdar://problem/43623196

llvm-svn: 341123

3 files changed, 59 insertions, 0 deletions

diff --git a/llvm/test/tools/dsymutil/Inputs/modules-pruning/1.o b/llvm/test/tools/dsymutil/Inputs/modules-pruning/1.o
new file mode 100644
index 00000000000..89cb1b467ed
--- /dev/null
+++ b/llvm/test/tools/dsymutil/Inputs/modules-pruning/1.o
diff --git a/llvm/test/tools/dsymutil/Inputs/modules-pruning/Outer.pcm b/llvm/test/tools/dsymutil/Inputs/modules-pruning/Outer.pcm
new file mode 100644
index 00000000000..657a024a686
--- /dev/null
+++ b/llvm/test/tools/dsymutil/Inputs/modules-pruning/Outer.pcm
diff --git a/llvm/test/tools/dsymutil/X86/modules-pruning.cpp b/llvm/test/tools/dsymutil/X86/modules-pruning.cpp
new file mode 100644
index 00000000000..7f331f183f0
--- /dev/null
+++ b/llvm/test/tools/dsymutil/X86/modules-pruning.cpp
@@ -0,0 +1,59 @@
+// RUN: dsymutil -f -oso-prepend-path=%p/../Inputs/modules-pruning \
+// RUN:   -y %p/dummy-debug-map.map -o - \
+// RUN:     | llvm-dwarfdump --name isRef -p - | FileCheck %s
+
+/* Compile with:
+   cat >modules.modulemap <<EOF
+   module Outer {
+     module Template {
+       header "template.h"
+       export *
+     }
+   }
+EOF
+   clang++ -D TEMPLATE_H -E -o template.h modules-pruning.cpp
+   clang++ -c -fcxx-modules -fmodules -fmodule-map-file=modules.modulemap \
+     -g -gmodules -fmodules-cache-path=. \
+     -Xclang -fdisable-module-hash modules-pruning.cpp -o 1.o
+*/
+
+// CHECK: DW_TAG_compile_unit
+// CHECK:   DW_TAG_module
+// CHECK:     DW_TAG_module
+// CHECK:       DW_TAG_class
+// CHECK:         DW_TAG_member
+// CHECK:           DW_AT_name ("isRef")
+// CHECK:           DW_AT_declaration (true)
+// CHECK:           DW_AT_const_value (1)
+// CHECK-NOT: DW_TAG
+
+#ifdef TEMPLATE_H
+
+namespace M {
+struct false_type {
+  static const bool value = false;
+};
+struct true_type {
+  static const bool value = true;
+};
+
+template <class T> struct is_reference      : false_type {};
+template <class T> struct is_reference<T&>  : true_type {};
+
+template<class T>
+class Template {
+public:
+  static const bool isRef = is_reference<T>::value;
+  Template() {}
+};
+}
+#else
+
+#include "template.h"
+
+void foo() {
+  M::Template<bool&> TB1;
+  TB1.isRef;
+}
+
+#endif