[VFS] Handle empty entries in directory traversal

The VFS YAML files contain empty directory entries to describe that it's
returning from a subdirectory before describing new files in the parent.
In the future, we should properly sort and write YAML files avoiding
such empty dirs and mitigate the extra recurson cost. However, since
this is used by previous existing YAMLs, make the traversal work in
their presence.

rdar://problem/24499339

llvm-svn: 264970

6 files changed, 74 insertions, 8 deletions

diff --git a/clang/lib/Basic/VirtualFileSystem.cpp b/clang/lib/Basic/VirtualFileSystem.cpp
index 325e5eb7bb7..a44111a3885 100644
--- a/clang/lib/Basic/VirtualFileSystem.cpp
+++ b/clang/lib/Basic/VirtualFileSystem.cpp
@@ -1358,16 +1358,21 @@ RedirectingFileSystem::lookupPath(sys::path::const_iterator Start,
     ++Start;
 #endif
 
-  if (CaseSensitive ? !Start->equals(From->getName())
-                    : !Start->equals_lower(From->getName()))
-    // failure to match
-    return make_error_code(llvm::errc::no_such_file_or_directory);
+  StringRef FromName = From->getName();
 
-  ++Start;
+  // Forward the search to the next component in case this is an empty one.
+  if (!FromName.empty()) {
+    if (CaseSensitive ? !Start->equals(FromName)
+                      : !Start->equals_lower(FromName))
+      // failure to match
+      return make_error_code(llvm::errc::no_such_file_or_directory);
 
-  if (Start == End) {
-    // Match!
-    return From;
+    ++Start;
+
+    if (Start == End) {
+      // Match!
+      return From;
+    }
   }
 
   auto *DE = dyn_cast<RedirectingDirectoryEntry>(From);
diff --git a/clang/test/Modules/Inputs/crash-recovery/usr/include/module.map b/clang/test/Modules/Inputs/crash-recovery/usr/include/module.map
index 70aae494eff..9b429160db5 100644
--- a/clang/test/Modules/Inputs/crash-recovery/usr/include/module.map
+++ b/clang/test/Modules/Inputs/crash-recovery/usr/include/module.map
@@ -3,4 +3,14 @@ module cstd [system] {
   module stdio {
     header "stdio.h"
   }
+
+  module pthread {
+    header "pthread.h"
+    export *
+
+    module impl {
+      header "pthread_impl.h"
+      export *
+    }
+  }
 }
diff --git a/clang/test/Modules/Inputs/crash-recovery/usr/include/pthread.h b/clang/test/Modules/Inputs/crash-recovery/usr/include/pthread.h
new file mode 100644
index 00000000000..44ac9fce952
--- /dev/null
+++ b/clang/test/Modules/Inputs/crash-recovery/usr/include/pthread.h
@@ -0,0 +1 @@
+#include "pthread/pthread_impl.h"
diff --git a/clang/test/Modules/Inputs/crash-recovery/usr/include/pthread/pthread_impl.h b/clang/test/Modules/Inputs/crash-recovery/usr/include/pthread/pthread_impl.h
new file mode 100644
index 00000000000..21a720a7c3c
--- /dev/null
+++ b/clang/test/Modules/Inputs/crash-recovery/usr/include/pthread/pthread_impl.h
@@ -0,0 +1 @@
+#define _PTHREAD_MUTEX_SIG_init   0x32AAABA7
diff --git a/clang/test/Modules/Inputs/crash-recovery/usr/include/pthread_impl.h b/clang/test/Modules/Inputs/crash-recovery/usr/include/pthread_impl.h
new file mode 100644
index 00000000000..21a720a7c3c
--- /dev/null
+++ b/clang/test/Modules/Inputs/crash-recovery/usr/include/pthread_impl.h
@@ -0,0 +1 @@
+#define _PTHREAD_MUTEX_SIG_init   0x32AAABA7
diff --git a/clang/test/Modules/crash-vfs-path-emptydir-entries.m b/clang/test/Modules/crash-vfs-path-emptydir-entries.m
new file mode 100644
index 00000000000..444c4556b51
--- /dev/null
+++ b/clang/test/Modules/crash-vfs-path-emptydir-entries.m
@@ -0,0 +1,48 @@
+// REQUIRES: crash-recovery, shell
+
+// FIXME: This XFAIL is cargo-culted from crash-report.c. Do we need it?
+// XFAIL: mingw32
+
+// Test clang can collect symbolic link headers used in modules.
+// crash reproducer if there's a symbolic link header file used in a module.
+
+// RUN: rm -rf %t
+// RUN: mkdir -p %t/i %t/m %t %t/sysroot
+// RUN: cp -a %S/Inputs/crash-recovery/usr %t/i/
+
+// RUN: not env FORCE_CLANG_DIAGNOSTICS_CRASH= TMPDIR=%t TEMP=%t TMP=%t \
+// RUN: %clang -fsyntax-only %s -I %/t/i -isysroot %/t/sysroot/ \
+// RUN:     -fmodules -fmodules-cache-path=%t/m/ 2>&1 | FileCheck %s
+
+// RUN: FileCheck --check-prefix=CHECKSRC %s -input-file %t/crash-vfs-*.m
+// RUN: FileCheck --check-prefix=CHECKSH %s -input-file %t/crash-vfs-*.sh
+// RUN: FileCheck --check-prefix=CHECKYAML %s -input-file \
+// RUN: %t/crash-vfs-*.cache/vfs/vfs.yaml
+// RUN: find %t/crash-vfs-*.cache/vfs | \
+// RUN:   grep "usr/include/stdio.h" | count 1
+
+#include "usr/include/stdio.h"
+
+// CHECK: Preprocessed source(s) and associated run script(s) are located at:
+// CHECK-NEXT: note: diagnostic msg: {{.*}}.m
+// CHECK-NEXT: note: diagnostic msg: {{.*}}.cache
+
+// CHECKSRC: @import cstd.stdio;
+
+// CHECKSH: # Crash reproducer
+// CHECKSH-NEXT: # Driver args: "-fsyntax-only"
+// CHECKSH-NEXT: # Original command: {{.*$}}
+// CHECKSH-NEXT: "-cc1"
+// CHECKSH: "-isysroot" "{{[^"]*}}/sysroot/"
+// CHECKSH-NOT: "-fmodules-cache-path="
+// CHECKSH: "crash-vfs-{{[^ ]*}}.m"
+// CHECKSH: "-ivfsoverlay" "crash-vfs-{{[^ ]*}}.cache/vfs/vfs.yaml"
+
+// CHECKYAML: 'type': 'directory',
+// CHECKYAML: 'name': "",
+// CHECKYAML-NEXT: 'contents': [
+// CHECKYAML-NEXT:   {
+// CHECKYAML-NEXT:     'type': 'file',
+// CHECKYAML-NEXT:     'name': "pthread_impl.h",
+// CHECKYAML-NEXT:     'external-contents': "/{{.*}}/i/usr/include/pthread_impl.h"
+// CHECKYAML-NEXT:   },