Start reifying error descriptions (Re-do of D23672 supporting VS2013)

[filcab]

Summary

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

This commit sets up the infrastructure to use reified error
descriptions, and moves ReportStackOverflow to the new system.

After we convert all the errors, we'll be able to simplify ScopedInErrorReport
and remove the older debugging mechanism which had some errors partly reified
in some way. We'll be able to maintain the external API.

ScopedInErrorReport will be able to track one of the reified errors at a time.
The purpose of this is so we have its destructor actually print the error and
possibly interface with the debugger (will depend on the platform, of course).

[kcc]

LGTM

[kcc]

BTW, please don't include samsonov@ and timurrrr@ into the following code reviews.
They have moved to other projects.

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"