Split ScarinessScore between its "storage" (POD), and an initializing object.

[filcab]

Summary

This is needed so we can use it for D23672 on VS2013, since this VS
version doesn't support unrestricted unions, and doesn't allow us to
uses an object without a trivial default constructor inside a union.

[filcab]

Updated to account for D24029.
Kostya: I know you've accepted the revision, but since this is a non-trivial change, I'm updating it to show why D24029 would help.

[filcab]

Merged two commits by mistake.

[kcc]

LGTM

lib/asan/CMakeLists.txt

 # Build for the AddressSanitizer runtime support library.
 
 set(ASAN_SOURCES
   asan_allocator.cc
   asan_activation.cc
   asan_debugging.cc
   asan_descriptions.cc
+  asan_errors.cc
   asan_fake_stack.cc
   asan_flags.cc
   asan_globals.cc
   asan_interceptors.cc
   asan_linux.cc
   asan_mac.cc
   asan_malloc_linux.cc
   asan_malloc_mac.cc

lib/asan/asan_errors.h

+//===-- asan_errors.h -------------------------------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file is a part of AddressSanitizer, an address sanity checker.
+//
+// ASan-private header for error structures.
+//===----------------------------------------------------------------------===//
+#ifndef ASAN_ERRORS_H
+#define ASAN_ERRORS_H
+
+#include "asan_descriptions.h"
+#include "asan_scariness_score.h"
+
+namespace __asan {
+
+struct ErrorBase {
+  ScarinessScoreBase scariness;
+};
+
+struct ErrorStackOverflow : ErrorBase {
+  u32 tid;
+  uptr addr, pc, bp, sp;
+  // ErrorStackOverflow never owns the context.
+  void *context;
+  // VS2013 doesn't implement unrestricted unions, so we need a trivial default
+  // constructor
+  ErrorStackOverflow() = default;
+  ErrorStackOverflow(const SignalContext &sig, u32 tid_)
+      : tid(tid_),
+        addr(sig.addr),
+        pc(sig.pc),
+        bp(sig.bp),
+        sp(sig.sp),
+        context(sig.context) {
+    scariness.Clear();
+    scariness.Scare(10, "stack-overflow");
+  }
+  void Print();
+};
+
+enum ErrorKind {
+  kErrorKindInvalid = 0,
+  kErrorKindStackOverflow,
+};
+
+struct ErrorDescription {
+  ErrorKind kind;
+  // We're using a tagged union because it allows us to have a trivially
+  // copiable type and use the same structures as the public interface.
+  //
+  // We can add a wrapper around it to make it "more c++-like", but that would
+  // add a lot of code and the benefit wouldn't be that big.
+  union {
+    ErrorStackOverflow stack_overflow;
+  };
+  ErrorDescription() { internal_memset(this, 0, sizeof(*this)); }
+  ErrorDescription(const ErrorStackOverflow &e)  // NOLINT
+      : kind(kErrorKindStackOverflow),
+        stack_overflow(e) {}
+
+  bool IsValid() { return kind != kErrorKindInvalid; }
+  void Print() {
+    switch (kind) {
+      case kErrorKindStackOverflow:
+        stack_overflow.Print();
+        return;
+      case kErrorKindInvalid:
+        CHECK(0);
+    }
+    CHECK(0);
+  }
+};
+
+}  // namespace __asan
+
+#endif  // ASAN_ERRORS_H

lib/asan/asan_errors.cc

+//===-- asan_errors.cc ------------------------------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file is a part of AddressSanitizer, an address sanity checker.
+//
+// ASan implementation for error structures.
+//===----------------------------------------------------------------------===//
+
+#include "asan_errors.h"
+#include "asan_stack.h"
+
+namespace __asan {
+
+void ErrorStackOverflow::Print() {
+  Decorator d;
+  Printf("%s", d.Warning());
+  Report(
+      "ERROR: AddressSanitizer: stack-overflow on address %p"
+      " (pc %p bp %p sp %p T%d)\n",
+      (void *)addr, (void *)pc, (void *)bp, (void *)sp, tid);
+  Printf("%s", d.EndWarning());
+  scariness.Print();
+  BufferedStackTrace stack;
+  GetStackTraceWithPcBpAndContext(&stack, kStackTraceMax, pc, bp, context,
+                                  common_flags()->fast_unwind_on_fatal);
+  stack.Print();
+  ReportErrorSummary("stack-overflow", &stack);
+}
+
+}  // namespace __asan

lib/asan/asan_report.cc

 //===-- asan_report.cc ----------------------------------------------------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 //
 // This file is a part of AddressSanitizer, an address sanity checker.
 //
 // This file contains error reporting code.
 //===----------------------------------------------------------------------===//
 
+#include "asan_errors.h"
 #include "asan_flags.h"
 #include "asan_descriptions.h"
 #include "asan_internal.h"
 #include "asan_mapping.h"
 #include "asan_report.h"
 #include "asan_scariness_score.h"
 #include "asan_stack.h"
 #include "asan_thread.h"
if (halt_on_error_) {
       // so it's safe to wait
       lock_.Lock();
     }
 
     StartReporting(report);
   }
 
   ~ScopedInErrorReport() {
+    if (current_error_.IsValid()) current_error_.Print();
+
     // Make sure the current thread is announced.
     DescribeThread(GetCurrentThread());
     // We may want to grab this lock again when printing stats.
     asanThreadRegistry().Unlock();
     // Print memory stats.
     if (flags()->print_stats)
       __asan_print_accumulated_stats();
 
~ScopedInErrorReport() {
     reporting_thread_tid_ = kInvalidTid;
     lock_.Unlock();
     if (halt_on_error_) {
       Report("ABORTING\n");
       Die();
     }
   }
 
+  void ReportError(const ErrorDescription &description) {
+    // Can only report one error per ScopedInErrorReport.
+    CHECK_EQ(current_error_.kind, kErrorKindInvalid);
+    current_error_ = description;
+  }
+
  private:
   void StartReporting(ReportData *report) {
     if (report) report_data = *report;
     report_happened = true;
     ASAN_ON_ERROR();
     // Make sure the registry and sanitizer report mutexes are locked while
     // we're printing an error report.
     // We can lock them only here to avoid self-deadlock in case of
     // recursive reports.
     asanThreadRegistry().Lock();
     CommonSanitizerReportMutex.Lock();
     reporting_thread_tid_ = GetCurrentTidOrInvalid();
     Printf("===================================================="
            "=============\n");
   }
 
   static StaticSpinMutex lock_;
   static u32 reporting_thread_tid_;
+  // Error currently being reported. This enables the destructor to interact
+  // with the debugger and point it to an error description.
+  static ErrorDescription current_error_;
   bool halt_on_error_;
 };
 
 StaticSpinMutex ScopedInErrorReport::lock_;
 u32 ScopedInErrorReport::reporting_thread_tid_ = kInvalidTid;
+ErrorDescription ScopedInErrorReport::current_error_;
 
 void ReportStackOverflow(const SignalContext &sig) {
   ScopedInErrorReport in_report(/*report*/ nullptr, /*fatal*/ true);
-  Decorator d;
-  Printf("%s", d.Warning());
-  Report(
-      "ERROR: AddressSanitizer: stack-overflow on address %p"
-      " (pc %p bp %p sp %p T%d)\n",
-      (void *)sig.addr, (void *)sig.pc, (void *)sig.bp, (void *)sig.sp,
-      GetCurrentTidOrInvalid());
-  Printf("%s", d.EndWarning());
-  ScarinessScore::PrintSimple(10, "stack-overflow");
-  GET_STACK_TRACE_SIGNAL(sig);
-  stack.Print();
-  ReportErrorSummary("stack-overflow", &stack);
+  ErrorStackOverflow error{sig, GetCurrentTidOrInvalid()};  // NOLINT
+  in_report.ReportError(error);
 }
 
 void ReportDeadlySignal(const char *description, const SignalContext &sig) {
   ScopedInErrorReport in_report(/*report*/ nullptr, /*fatal*/ true);
   Decorator d;
   Printf("%s", d.Warning());
   Report(
       "ERROR: AddressSanitizer: %s on unknown address %p"

lib/asan/asan_scariness_score.h

 #ifndef ASAN_SCARINESS_SCORE_H
 #define ASAN_SCARINESS_SCORE_H
 
 #include "asan_flags.h"
 #include "sanitizer_common/sanitizer_common.h"
 #include "sanitizer_common/sanitizer_libc.h"
 
 namespace __asan {
-class ScarinessScore {
- public:
-  ScarinessScore() {
+struct ScarinessScoreBase {
+  void Clear() {
     descr[0] = 0;
+    score = 0;
   }
   void Scare(int add_to_score, const char *reason) {
     if (descr[0])
       internal_strlcat(descr, "-", sizeof(descr));
     internal_strlcat(descr, reason, sizeof(descr));
     score += add_to_score;
   };
   int GetScore() const { return score; }
   const char *GetDescription() const { return descr; }
   void Print() {
     if (score && flags()->print_scariness)
       Printf("SCARINESS: %d (%s)\n", score, descr);
   }
   static void PrintSimple(int score, const char *descr) {
-    ScarinessScore SS;
-    SS.Scare(score, descr);
-    SS.Print();
+    ScarinessScoreBase SSB;
+    SSB.Clear();
+    SSB.Scare(score, descr);
+    SSB.Print();
   }
 
  private:
-  int score = 0;
+  int score;
   char descr[1024];
 };
 
+struct ScarinessScore : ScarinessScoreBase {
+  ScarinessScore() {
+    Clear();
+  }
+};
+
 }  // namespace __asan
 
 #endif  // ASAN_SCARINESS_SCORE_H