Revert "Reland "[vm] Remove warnings about non-standard stack traces.""

This reverts commit 6651c29779.

Reason for revert: breaks google3 (b/236928633)

Original change's description:
> Reland "[vm] Remove warnings about non-standard stack traces."
>
> This is a reland of commit cc9d14d822
>
> TEST=vm/dart{,_2}/causal_stacks/async_throws_stack_lazy_non_symbolic_test
>
> Original change's description:
> > [vm] Remove warnings about non-standard stack traces.
> >
> > The language team has clarified in
> > https://github.com/dart-lang/language/issues/1212 that the content of
> > stack traces is not specified in a way that is violated by either
> > obfuscation or non-symbolic stack traces. Thus, we remove the warnings
> > about supposedly standard-violating stack traces.
> >
> > TEST=No change in actual functionality, so tested manually.
> >
> > Bug: https://github.com/dart-lang/sdk/issues/43388
> > Change-Id: I2c7ac44cf2f9afafa85d902b2783e1173e727264
> > Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/249185
> > Commit-Queue: Tess Strickland <sstrickl@google.com>
> > Reviewed-by: Daco Harkes <dacoharkes@google.com>
> > Reviewed-by: Martin Kustermann <kustermann@google.com>
>
> Bug: https://github.com/dart-lang/sdk/issues/43388
> Change-Id: Ifa7915b4ba21cca592ed5645cd9ad6cda1575f12
> Cq-Include-Trybots: luci.dart.try:vm-kernel-precomp-dwarf-linux-product-x64-try,vm-kernel-precomp-linux-debug-x64-try,vm-kernel-precomp-linux-product-x64-try,vm-kernel-precomp-nnbd-linux-release-x64-try
> Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/249192
> Commit-Queue: Tess Strickland <sstrickl@google.com>
> Reviewed-by: Martin Kustermann <kustermann@google.com>
> Reviewed-by: Daco Harkes <dacoharkes@google.com>

TBR=kustermann@google.com,dacoharkes@google.com,sstrickl@google.com

Change-Id: I65f3d84caee3ec9ac30f0ce058104bb24ef6ea11
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: https://github.com/dart-lang/sdk/issues/43388
Cq-Include-Trybots: luci.dart.try:vm-kernel-precomp-dwarf-linux-product-x64-try,vm-kernel-precomp-linux-debug-x64-try,vm-kernel-precomp-linux-product-x64-try,vm-kernel-precomp-nnbd-linux-release-x64-try
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/249580
Commit-Queue: Emmanuel Pellereau <emmanuelp@google.com>
Reviewed-by: Martin Kustermann <kustermann@google.com>
Reviewed-by: Emmanuel Pellereau <emmanuelp@google.com>

runtime/tests/vm/dart/causal_stacks/utils.dart

@@ -205,26 +205,21 @@ Future<void> assertStack(List<String> expects, StackTrace stackTrace,
 
   // Use the DWARF stack decoder if we're running in --dwarf-stack-traces mode
   // and in precompiled mode (otherwise --dwarf-stack-traces has no effect).
-  bool usingDwarf = false;
-  if (debugInfoFilename != null) {
-    try {
-      final dwarf = Dwarf.fromFile(debugInfoFilename)!;
-      usingDwarf = true;
-      frames = await Stream.fromIterable(original)
-          .transform(DwarfStackTraceDecoder(dwarf))
-          .where(_lineRE.hasMatch)
-          .toList();
-    } on FileSystemException {
-      // We're not running in precompiled mode, so the file doesn't exist and
-      // we can continue normally.
-    }
+  final decodeTrace = frames.first.startsWith('Warning:');
+  if (decodeTrace) {
+    Expect.isNotNull(debugInfoFilename);
+    final dwarf = Dwarf.fromFile(debugInfoFilename!)!;
+    frames = await Stream.fromIterable(original)
+        .transform(DwarfStackTraceDecoder(dwarf))
+        .where(_lineRE.hasMatch)
+        .toList();
   }
 
   void printFrameInformation() {
     print('RegExps for expected stack:');
     expects.forEach((s) => print('"${s}"'));
     print('');
-    if (usingDwarf) {
+    if (decodeTrace) {
       print('Non-symbolic actual stack:');
       original.forEach(print);
       print('');

runtime/tests/vm/dart_2/causal_stacks/utils.dart

@@ -207,26 +207,21 @@ Future<void> assertStack(List<String> expects, StackTrace stackTrace,
 
   // Use the DWARF stack decoder if we're running in --dwarf-stack-traces mode
   // and in precompiled mode (otherwise --dwarf-stack-traces has no effect).
-  bool usingDwarf = false;
-  if (debugInfoFilename != null) {
-    try {
-      final dwarf = Dwarf.fromFile(debugInfoFilename);
-      usingDwarf = true;
-      frames = await Stream.fromIterable(original)
-          .transform(DwarfStackTraceDecoder(dwarf))
-          .where(_lineRE.hasMatch)
-          .toList();
-    } on FileSystemException {
-      // We're not running in precompiled mode, so the file doesn't exist and
-      // we can continue normally.
-    }
+  final decodeTrace = frames.first.startsWith('Warning:');
+  if (decodeTrace) {
+    Expect.isNotNull(debugInfoFilename);
+    final dwarf = Dwarf.fromFile(debugInfoFilename);
+    frames = await Stream.fromIterable(original)
+        .transform(DwarfStackTraceDecoder(dwarf))
+        .where(_lineRE.hasMatch)
+        .toList();
   }
 
   void printFrameInformation() {
     print('RegExps for expected stack:');
     expects.forEach((s) => print('"${s}"'));
     print('');
-    if (usingDwarf) {
+    if (decodeTrace) {
       print('Non-symbolic actual stack:');
       original.forEach(print);
       print('');

runtime/vm/isolate.cc

@@ -1739,6 +1739,13 @@ Isolate::Isolate(IsolateGroup* isolate_group,
   // how the vm_tag (kEmbedderTagId) can be set, these tags need to
   // move to the OSThread structure.
   set_user_tag(UserTags::kDefaultUserTag);
+
+  if (group()->obfuscate()) {
+    OS::PrintErr(
+        "Warning: This VM has been configured to obfuscate symbol information "
+        "which violates the Dart standard.\n"
+        "         See dartbug.com/30524 for more information.\n");
+  }
 }
 
 #undef REUSABLE_HANDLE_SCOPE_INIT

runtime/vm/object.cc

@@ -25878,6 +25878,12 @@ const char* StackTrace::ToCString() const {
         isolate_instructions_image.instructions_relocated_address();
     auto const vm_relocated_address =
         vm_instructions_image.instructions_relocated_address();
+    // The Dart standard requires the output of StackTrace.toString to include
+    // all pending activations with precise source locations (i.e., to expand
+    // inlined frames and provide line and column numbers).
+    buffer.Printf(
+        "Warning: This VM has been configured to produce stack traces "
+        "that violate the Dart standard.\n");
     // This prologue imitates Android's debuggerd to make it possible to paste
     // the stack trace into ndk-stack.
     buffer.Printf(