Initial support for dumping DWARF corresponding to Swift code

src/common/language.cc

 // Copyright (c) 2010 Google Inc.
 // All rights reserved.
 //
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 // notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
@@ skipping 16 matching lines @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 // Original author: Jim Blandy <jimb@mozilla.com> <jimb@red-bean.com>
 
 // language.cc: Subclasses and singletons for google_breakpad::Language.
 // See language.h for details.
 
 #include "common/language.h"
 
+#include <stdlib.h>
+
+#if !defined(__ANDROID__)
+#include <cxxabi.h>
+#endif
+
+#include <limits>
+
+namespace {
+
+string MakeQualifiedNameWithSeparator(const string& parent_name,
+                                      const char* separator,
+                                      const string& name) {
+  if (parent_name.empty()) {
+    return name;
+  }
+
+  return parent_name + separator + name;
+}
+
+}  // namespace
+
 namespace google_breakpad {
 
+const int Language::kDontDemangle = std::numeric_limits<int>::min();
+
 // C++ language-specific operations.
 class CPPLanguage: public Language {
  public:
   CPPLanguage() {}
+
   string MakeQualifiedName(const string &parent_name,
                            const string &name) const {
-    if (parent_name.empty())
-      return name;
-    else
-      return parent_name + "::" + name;
+    return MakeQualifiedNameWithSeparator(parent_name, "::", name);
+  }
+
+  virtual int DemangleName(const string& mangled, std::string* demangled)
+      const {
+    char* demangled_c = NULL;
+    int status = kDontDemangle;
+#if !defined(__ANDROID__)  // Android NDK doesn't provide abi::__cxa_demangle.
+    demangled_c = abi::__cxa_demangle(mangled.c_str(), NULL, NULL, &status);
+#endif

[Ted Mielczarek, 2016/09/14 10:20:10]

This seems like it'd be clearer to read if it was just:
#if defined(__ANDROID__)
  return whatever;
#else
  // actually try to demangle
#endif

+
+    if (status != 0) {
+      demangled->clear();
+    } else {
+      demangled->assign(demangled_c);
+    }
+
+    if (demangled_c) {
+      free(reinterpret_cast<void*>(demangled_c));
+    }
+
+    return status;
   }
 };
 
 CPPLanguage CPPLanguageSingleton;
 
 // Java language-specific operations.
 class JavaLanguage: public Language {
  public:
+  JavaLanguage() {}
+
   string MakeQualifiedName(const string &parent_name,
                            const string &name) const {
-    if (parent_name.empty())
-      return name;
-    else
-      return parent_name + "." + name;
+    return MakeQualifiedNameWithSeparator(parent_name, ".", name);
   }
 };
 
 JavaLanguage JavaLanguageSingleton;
 
+// Swift language-specific operations.
+class SwiftLanguage: public Language {
+ public:
+  SwiftLanguage() {}
+
+  string MakeQualifiedName(const string &parent_name,
+                           const string &name) const {
+    return MakeQualifiedNameWithSeparator(parent_name, ".", name);
+  }
+
+  virtual int DemangleName(const string& mangled, std::string* demangled)
+      const {
+    // There is no programmatic interface to a Swift demangler. Pass through the
+    // mangled form because it encodes more information than the qualified name
+    // that would have been built by MakeQualifiedName(). The output can be
+    // post-processed by xcrun swift-demangle to transform mangled Swift names
+    // into something more readable.
+    demangled->assign(mangled);
+    return 0;
+  }
+};
+
+SwiftLanguage SwiftLanguageSingleton;
+
 // Assembler language-specific operations.
 class AssemblerLanguage: public Language {
+ public:
+  AssemblerLanguage() {}
+
   bool HasFunctions() const { return false; }
   string MakeQualifiedName(const string &parent_name,
                            const string &name) const {
     return name;
   }
 };
 
 AssemblerLanguage AssemblerLanguageSingleton;
 
 const Language * const Language::CPlusPlus = &CPPLanguageSingleton;
 const Language * const Language::Java = &JavaLanguageSingleton;
+const Language * const Language::Swift = &SwiftLanguageSingleton;
 const Language * const Language::Assembler = &AssemblerLanguageSingleton;
 
 } // namespace google_breakpad