[CrashReproducer] Add a module map callback for added headers

The current ModuleDependencyCollector has a AST listener to collect
header files present in loaded modules, but this isn't enough to collect
all headers needed in the crash reproducer. One of the reasons is that
the AST writer doesn't write symbolic link header paths in the pcm modules,
this makes the listeners on the reader only able to collect the real files.

Since the module maps could contain submodules that use headers which
are symbolic links, not collecting those forbid the reproducer scripts
to regen the modules.

For instance:

usr/include/module.map:
  ...
  module pthread {
    header "pthread.h"
    export *

    module impl {
      header "pthread_impl.h"
      export *
    }
  }
  ...

usr/include/pthread/pthread_impl.h
usr/include/pthread_impl.h -> pthread/pthread_impl.h

The AST dump for the module above:

  <SUBMODULE_HEADER abbrevid=6/> blob data = 'pthread_impl.h'
  <SUBMODULE_TOPHEADER abbrevid=7/> blob data = '/<path_to_sdk>/usr/include/pthread/pthread_impl.h'

Note that we don't have "usr/include/pthread_impl.h" which is requested
by the module.map in case we want to reconstruct the module in the
reproducer. The reason the original symbolic link path isn't used is
because the headers are kept by name and requested through the
FileManager, which unique files and returns the real path only.

To fix that, add a callback to be invoked everytime a header is added
while parsing module maps and hook that up to the module dependecy
collector. This callback is only registered when generating the
reproducer.

Differential Revision: http://reviews.llvm.org/D18585

rdar://problem/24499339

llvm-svn: 264971

clang/include/clang/Frontend/Utils.h

@@ -77,7 +77,7 @@ void DoPrintPreprocessedInput(Preprocessor &PP, raw_ostream* OS,
 /// interface.
 class DependencyCollector {
 public:
-  void attachToPreprocessor(Preprocessor &PP);
+  virtual void attachToPreprocessor(Preprocessor &PP);
   virtual void attachToASTReader(ASTReader &R);
   llvm::ArrayRef<std::string> getDependencies() const { return Dependencies; }
 
@@ -136,6 +136,7 @@ class ModuleDependencyCollector : public DependencyCollector {
     VFSWriter.addFileMapping(VPath, RPath);
   }
 
+  void attachToPreprocessor(Preprocessor &PP) override;
   void attachToASTReader(ASTReader &R) override;
 
   void writeFileMap();

clang/include/clang/Lex/ModuleMap.h

@@ -50,6 +50,11 @@ class ModuleMapCallbacks {
   /// \param IsSystem Whether this is a module map from a system include path.
   virtual void moduleMapFileRead(SourceLocation FileStart,
                                  const FileEntry &File, bool IsSystem) {}
+
+  /// \brief Called when a header is added during module map parsing.
+  ///
+  /// \param File The header file itself.
+  virtual void moduleMapAddHeader(const FileEntry &File) {}
 };
 
 class ModuleMap {

clang/lib/Frontend/ModuleDependencyCollector.cpp

@@ -12,6 +12,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "clang/Frontend/Utils.h"
+#include "clang/Lex/Preprocessor.h"
 #include "clang/Serialization/ASTReader.h"
 #include "llvm/ADT/StringMap.h"
 #include "llvm/ADT/iterator_range.h"
@@ -22,7 +23,7 @@
 using namespace clang;
 
 namespace {
-/// Private implementation for ModuleDependencyCollector
+/// Private implementations for ModuleDependencyCollector
 class ModuleDependencyListener : public ASTReaderListener {
   ModuleDependencyCollector &Collector;
 public:
@@ -36,12 +37,30 @@ class ModuleDependencyListener : public ASTReaderListener {
     return true;
   }
 };
+
+struct ModuleDependencyMMCallbacks : public ModuleMapCallbacks {
+  ModuleDependencyCollector &Collector;
+  ModuleDependencyMMCallbacks(ModuleDependencyCollector &Collector)
+      : Collector(Collector) {}
+
+  void moduleMapAddHeader(const FileEntry &File) override {
+    StringRef HeaderPath = File.getName();
+    if (llvm::sys::path::is_absolute(HeaderPath))
+      Collector.addFile(HeaderPath);
+  }
+};
+
 }
 
 void ModuleDependencyCollector::attachToASTReader(ASTReader &R) {
   R.addListener(llvm::make_unique<ModuleDependencyListener>(*this));
 }
 
+void ModuleDependencyCollector::attachToPreprocessor(Preprocessor &PP) {
+  PP.getHeaderSearchInfo().getModuleMap().addModuleMapCallbacks(
+      llvm::make_unique<ModuleDependencyMMCallbacks>(*this));
+}
+
 void ModuleDependencyCollector::writeFileMap() {
   if (Seen.empty())
     return;

clang/lib/Lex/ModuleMap.cpp

@@ -811,6 +811,10 @@ void ModuleMap::addHeader(Module *Mod, Module::Header Header,
     HeaderInfo.MarkFileModuleHeader(Header.Entry, Role,
                                     isCompilingModuleHeader);
   }
+
+  // Notify callbacks that we just added a new header.
+  for (const auto &Cb : Callbacks)
+    Cb->moduleMapAddHeader(*Header.Entry);
 }
 
 void ModuleMap::excludeHeader(Module *Mod, Module::Header Header) {

clang/test/Modules/crash-vfs-path-symlink-topheader.m

@@ -0,0 +1,50 @@
+// 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: rm -f %t/i/usr/include/pthread_impl.h
+// RUN: ln -s pthread/pthread_impl.h %t/i/usr/include/pthread_impl.h
+
+// 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/pthread_impl.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:   },