Revert "[SDK] Adds an SDK hash to kernels and the VM."

This reverts commit edde575.

Reason for revert: Breaks the Dart to Flutter roll and golem

Original change's description:
> [SDK] Adds an SDK hash to kernels and the VM.
>
> Adds a new SDK hash to kernels and the VM which is optionally checked
> to verify kernels are built for the same SDK as the VM.
> This helps catch incompatibilities that are currently causing
> subtle bugs and (not so subtle) crashes.
>
> The SDK hash is encoded in kernels as a new field in components.
> The hash is derived from the 10 byte git short hash.
>
> This new check can be disabled via:
>   tools/gn.py ... --no-verify-sdk-hash
>
> This CL bumps the min. (and max.) supported kernel format version,
> making the VM backwards incompatible from this point back.
>
> Bug: #41802
> Change-Id: I3cbb2d481239ee64dafdaa0e4aac36c80281931b
> Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/150343
> Commit-Queue: Clement Skau <[email protected]>
> Reviewed-by: Jens Johansen <[email protected]>
> Reviewed-by: Martin Kustermann <[email protected]>

[email protected],[email protected],[email protected]

Change-Id: I34cc7d378e2babdaaca4d932d19c19d0f35422fc
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: #41802
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/152703
Reviewed-by: Siva Annamalai <[email protected]>
Commit-Queue: Siva Annamalai <[email protected]>

Author: a-siva

DEPS

@@ -512,7 +512,7 @@ deps = {
     "packages": [
       {
         "package": "dart/cfe/dart2js_dills",
-        "version": "binary_version:43_2",
+        "version": "binary_version:42",
       }
     ],
     "dep_type": "cipd",

pkg/front_end/test/binary_md_dill_reader.dart

@@ -473,33 +473,31 @@ class BinaryMdDillReader {
         type = type.substring(0, type.indexOf("["));
         type = _lookupGenericType(typeNames, type, types);
 
-        int intCount = int.tryParse(count) ?? -1;
-        if (intCount == -1) {
-          if (vars[count] != null && vars[count] is int) {
-            intCount = vars[count];
-          } else if (count.contains(".")) {
-            List<String> countData =
-                count.split(regExpSplit).map((s) => s.trim()).toList();
-            if (vars[countData[0]] != null) {
-              dynamic v = vars[countData[0]];
-              if (v is Map &&
-                  countData[1] == "last" &&
-                  v["items"] is List &&
-                  v["items"].last is int) {
-                intCount = v["items"].last;
-              } else if (v is Map && v[countData[1]] != null) {
-                v = v[countData[1]];
-                if (v is Map && v[countData[2]] != null) {
-                  v = v[countData[2]];
-                  if (v is int) intCount = v;
-                } else if (v is int &&
-                    countData.length == 4 &&
-                    countData[2] == "+") {
-                  intCount = v + int.parse(countData[3]);
-                }
-              } else {
-                throw "Unknown dot to int ($count)";
+        int intCount = -1;
+        if (vars[count] != null && vars[count] is int) {
+          intCount = vars[count];
+        } else if (count.contains(".")) {
+          List<String> countData =
+              count.split(regExpSplit).map((s) => s.trim()).toList();
+          if (vars[countData[0]] != null) {
+            dynamic v = vars[countData[0]];
+            if (v is Map &&
+                countData[1] == "last" &&
+                v["items"] is List &&
+                v["items"].last is int) {
+              intCount = v["items"].last;
+            } else if (v is Map && v[countData[1]] != null) {
+              v = v[countData[1]];
+              if (v is Map && v[countData[2]] != null) {
+                v = v[countData[2]];
+                if (v is int) intCount = v;
+              } else if (v is int &&
+                  countData.length == 4 &&
+                  countData[2] == "+") {
+                intCount = v + int.parse(countData[3]);
               }
+            } else {
+              throw "Unknown dot to int ($count)";
             }
           }
         }

pkg/front_end/test/spell_checking_list_code.txt

@@ -313,7 +313,6 @@ disallow
 disambiguator
 disjoint
 dispatched
-distribute
 divided
 dmitryas
 doc
@@ -326,7 +325,6 @@ downloaded
 downloading
 dq
 dquote
-dsdk
 dst
 dummy
 dupdate
@@ -437,14 +435,12 @@ futured
 futureor
 g
 gardening
-gen
 generation
 gets
 getter1a
 getter1b
 getting
 gft
-git
 github
 glb
 glob

pkg/kernel/binary.md

@@ -143,8 +143,7 @@ type CanonicalName {
 
 type ComponentFile {
   UInt32 magic = 0x90ABCDEF;
-  UInt32 formatVersion = 43;
-  Byte[10] shortSdkHash;
+  UInt32 formatVersion = 42;
   List<String> problemsAsJson; // Described in problems.md.
   Library[] libraries;
   UriSource sourceMap;

pkg/kernel/lib/binary/ast_from_binary.dart

@@ -5,7 +5,6 @@ library kernel.ast_from_binary;
 
 import 'dart:core' hide MapEntry;
 import 'dart:developer';
-import 'dart:convert';
 import 'dart:typed_data';
 
 import '../ast.dart';
@@ -29,22 +28,11 @@ class InvalidKernelVersionError {
   InvalidKernelVersionError(this.version);
 
   String toString() {
-    return 'Unexpected Kernel Format Version ${version} '
+    return 'Unexpected Kernel version ${version} '
         '(expected ${Tag.BinaryFormatVersion}).';
   }
 }
 
-class InvalidKernelSdkVersionError {
-  final String version;
-
-  InvalidKernelSdkVersionError(this.version);
-
-  String toString() {
-    return 'Unexpected Kernel SDK Version ${version} '
-        '(expected ${expectedSdkHash}).';
-  }
-}
-
 class CompilationModeError {
   final String message;
 
@@ -496,13 +484,6 @@ class BinaryBuilder {
     if (_bytes.length == 0) throw new StateError("Empty input given.");
   }
 
-  void _readAndVerifySdkHash() {
-    final sdkHash = ascii.decode(readBytes(sdkHashLength));
-    if (!isValidSdkHash(sdkHash)) {
-      throw InvalidKernelSdkVersionError(sdkHash);
-    }
-  }
-
   /// Deserializes a kernel component and stores it in [component].
   ///
   /// When linking with a non-empty component, canonical names must have been
@@ -530,9 +511,6 @@ class BinaryBuilder {
       if (version != Tag.BinaryFormatVersion) {
         throw InvalidKernelVersionError(version);
       }
-
-      _readAndVerifySdkHash();
-
       _byteOffset = offset;
       List<int> componentFileSizes = _indexComponents();
       if (componentFileSizes.length > 1) {
@@ -716,8 +694,6 @@ class BinaryBuilder {
       throw InvalidKernelVersionError(formatVersion);
     }
 
-    _readAndVerifySdkHash();
-
     // Read component index from the end of this ComponentFiles serialized data.
     _ComponentIndex index = _readComponentIndex(componentFileSize);
 
@@ -742,8 +718,6 @@ class BinaryBuilder {
       throw InvalidKernelVersionError(formatVersion);
     }
 
-    _readAndVerifySdkHash();
-
     List<String> problemsAsJson = readListOfStrings();
     if (problemsAsJson != null) {
       component.problemsAsJson ??= <String>[];

pkg/kernel/lib/binary/ast_to_binary.dart

@@ -4,7 +4,6 @@
 library kernel.ast_to_binary;
 
 import 'dart:core' hide MapEntry;
-import 'dart:convert';
 import 'dart:developer';
 import 'dart:io' show BytesBuilder;
 import 'dart:typed_data';
@@ -538,7 +537,6 @@ class BinaryPrinter implements Visitor<void>, BinarySink {
       final componentOffset = getBufferOffset();
       writeUInt32(Tag.ComponentFile);
       writeUInt32(Tag.BinaryFormatVersion);
-      writeBytes(ascii.encode(expectedSdkHash));
       writeListOfStrings(component.problemsAsJson);
       indexLinkTable(component);
       _collectMetadata(component);

pkg/kernel/lib/binary/tag.dart

@@ -149,7 +149,7 @@ class Tag {
   /// Internal version of kernel binary format.
   /// Bump it when making incompatible changes in kernel binaries.
   /// Keep in sync with runtime/vm/kernel_binary.h, pkg/kernel/binary.md.
-  static const int BinaryFormatVersion = 43;
+  static const int BinaryFormatVersion = 42;
 }
 
 abstract class ConstantTag {
@@ -169,27 +169,3 @@ abstract class ConstantTag {
   static const int UnevaluatedConstant = 12;
   // 13 is occupied by [SetConstant]
 }
-
-const int sdkHashLength = 10; // Bytes, a Git "short hash".
-
-const String sdkHashNull = '0000000000';
-
-// Will be correct hash for Flutter SDK / Dart SDK we distribute.
-// If non-null we will validate when consuming kernel, will use when producing
-// kernel.
-// If null, local development setting (e.g. run gen_kernel.dart from source),
-// we put 0x00..00 into when producing, do not validate when consuming.
-String get expectedSdkHash {
-  final sdkHash =
-      const String.fromEnvironment('sdk_hash', defaultValue: sdkHashNull);
-  if (sdkHash.length != 10) {
-    throw '-Dsdk_hash=<hash> must be a 10 byte string!';
-  }
-  return sdkHash;
-}
-
-bool isValidSdkHash(String sdkHash) {
-  return (sdkHash == sdkHashNull ||
-      expectedSdkHash == sdkHashNull ||
-      sdkHash == expectedSdkHash);
-}

runtime/bin/BUILD.gn

@@ -964,11 +964,9 @@ prebuilt_dart_action("gen_kernel_bytecode_dill") {
 
   abs_depfile = rebase_path(depfile)
   rebased_output = rebase_path(output, root_build_dir)
-
   vm_args = [
     "--depfile=$abs_depfile",
     "--depfile_output_filename=$rebased_output",
-    "-Dsdk_hash=$sdk_hash",
   ]
 
   args = [

runtime/tests/vm/dart/sdk_hash_test.dart

@@ -48,7 +48,6 @@ final String executableSuffix = Platform.isWindows ? ".exe" : "";
 final String buildDir = p.dirname(Platform.executable);
 final String platformDill = p.join(buildDir, "vm_platform_strong.dill");
 final String genSnapshot = p.join(buildDir, "gen_snapshot${executableSuffix}");
-final String dart = p.join(buildDir, "dart${executableSuffix}");
 final String dartPrecompiledRuntime =
     p.join(buildDir, "dart_precompiled_runtime${executableSuffix}");
 final String genKernel = p.join("pkg", "vm", "bin", "gen_kernel.dart");