-gmodules: Don't emit incomplete breadcrumbs pointing to nonexistant PCM files.

When a module name is specified as -fmodule-name, that module gets a
clang::Module object, but it won't actually be built or imported; it
will be textual. CGDebugInfo wouldn't detect this and them emit a
DICompileUnit that had a hash but no name and that confused both
dsymutil, LLDB, and myself.

rdar://problem/47926508

Differential Revision: https://reviews.llvm.org/D57976

llvm-svn: 353578

1 files changed, 16 insertions, 0 deletions

diff --git a/clang/test/Modules/DebugInfo-fmodule-name.c b/clang/test/Modules/DebugInfo-fmodule-name.c
new file mode 100644
index 00000000000..6d962bcd274
--- /dev/null
+++ b/clang/test/Modules/DebugInfo-fmodule-name.c
@@ -0,0 +1,16 @@
+// RUN: rm -rf %t
+// RUN: %clang_cc1 -fmodules -fmodule-format=obj -fmodule-name=F \
+// RUN:     -debug-info-kind=limited -dwarf-ext-refs \
+// RUN:     -fimplicit-module-maps -x c -fmodules-cache-path=%t -F %S/Inputs \
+// RUN:     %s -S -emit-llvm -debugger-tuning=lldb -o - | FileCheck %s
+
+#include "F/F.h"
+
+// CHECK: !DICompileUnit
+// CHECK-NOT: dwoId:
+
+// We still want the import, but no skeleton CU, since no PCM was built.
+
+// CHECK: !DIModule({{.*}}, name: "F"
+// CHECK-NOT: !DICompileUnit
+// CHECK-NOT: dwoId: