[CFE] Indicate NNBD compilation mode on all libraries

Change-Id: I01236158b593d0e4bd7cf67017459f05fb9520a8
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/136128
Commit-Queue: Jens Johansen <jensj@google.com>
Reviewed-by: Johnni Winther <johnniwinther@google.com>

pkg/front_end/lib/src/fasta/source/source_library_builder.dart

@@ -36,6 +36,7 @@ import 'package:kernel/ast.dart'
         Member,
         Name,
         NeverType,
+        NonNullableByDefaultCompiledMode,
         Nullability,
         Procedure,
         ProcedureKind,
@@ -310,6 +311,11 @@ class SourceLibraryBuilder extends LibraryBuilderImpl {
         super(
             fileUri, libraryDeclaration.toScope(importScope), new Scope.top()) {
     library.isNonNullableByDefault = isNonNullableByDefault;
+    library.nonNullableByDefaultCompiledMode = loader.target.enableNonNullable
+        ? (loader.nnbdStrongMode
+            ? NonNullableByDefaultCompiledMode.Strong
+            : NonNullableByDefaultCompiledMode.Weak)
+        : NonNullableByDefaultCompiledMode.Disabled;
   }
 
   SourceLibraryBuilder(
@@ -958,6 +964,12 @@ class SourceLibraryBuilder extends LibraryBuilderImpl {
     }
 
     library.isNonNullableByDefault = isNonNullableByDefault;
+    // TODO(CFE Team): Is this really needed in two places?
+    library.nonNullableByDefaultCompiledMode = loader.target.enableNonNullable
+        ? (loader.nnbdStrongMode
+            ? NonNullableByDefaultCompiledMode.Strong
+            : NonNullableByDefaultCompiledMode.Weak)
+        : NonNullableByDefaultCompiledMode.Disabled;
 
     return library;
   }

pkg/front_end/test/spell_checking_list_code.txt

@@ -22,6 +22,7 @@ acov
 across
 affecting
 afterwards
+agnostic
 agree
 ahe
 ai
@@ -97,6 +98,8 @@ bin
 binder
 binders
 binds
+bit1
+bit2
 bj
 blob
 blocking

pkg/kernel/binary.md

@@ -143,7 +143,7 @@ type CanonicalName {
 
 type ComponentFile {
   UInt32 magic = 0x90ABCDEF;
-  UInt32 formatVersion = 39;
+  UInt32 formatVersion = 40;
   List<String> problemsAsJson; // Described in problems.md.
   Library[] libraries;
   UriSource sourceMap;
@@ -228,7 +228,8 @@ type Name {
 }
 
 type Library {
-  Byte flags (_unused_, isSynthetic, isNonNullableByDefault);
+  Byte flags (_unused_, isSynthetic, isNonNullableByDefault,
+              nnbdModeBit1, nnbdModeBit2);
   UInt languageVersionMajor;
   UInt languageVersionMinor;
   CanonicalNameReference canonicalName;

pkg/kernel/lib/ast.dart

@@ -315,6 +315,8 @@ class Reference {
 //                      LIBRARIES and CLASSES
 // ------------------------------------------------------------------------
 
+enum NonNullableByDefaultCompiledMode { Disabled, Weak, Strong, Agnostic }
+
 class Library extends NamedNode
     implements Annotatable, Comparable<Library>, FileUriNode {
   /// An import path to this library.
@@ -347,6 +349,8 @@ class Library extends NamedNode
 
   static const int SyntheticFlag = 1 << 1;
   static const int NonNullableByDefaultFlag = 1 << 2;
+  static const int NonNullableByDefaultModeBit1Weak = 1 << 3;
+  static const int NonNullableByDefaultModeBit2Strong = 1 << 4;
 
   int flags = 0;
 
@@ -364,6 +368,38 @@ class Library extends NamedNode
         : (flags & ~NonNullableByDefaultFlag);
   }
 
+  NonNullableByDefaultCompiledMode get nonNullableByDefaultCompiledMode {
+    bool weak = (flags & NonNullableByDefaultModeBit1Weak) != 0;
+    bool strong = (flags & NonNullableByDefaultModeBit2Strong) != 0;
+
+    if (weak && strong) return NonNullableByDefaultCompiledMode.Agnostic;
+    if (strong) return NonNullableByDefaultCompiledMode.Strong;
+    if (weak) return NonNullableByDefaultCompiledMode.Weak;
+    return NonNullableByDefaultCompiledMode.Disabled;
+  }
+
+  void set nonNullableByDefaultCompiledMode(
+      NonNullableByDefaultCompiledMode mode) {
+    switch (mode) {
+      case NonNullableByDefaultCompiledMode.Disabled:
+        flags = (flags & ~NonNullableByDefaultModeBit1Weak) &
+            ~NonNullableByDefaultModeBit2Strong;
+        break;
+      case NonNullableByDefaultCompiledMode.Weak:
+        flags = (flags | NonNullableByDefaultModeBit1Weak) &
+            ~NonNullableByDefaultModeBit2Strong;
+        break;
+      case NonNullableByDefaultCompiledMode.Strong:
+        flags = (flags & ~NonNullableByDefaultModeBit1Weak) |
+            NonNullableByDefaultModeBit2Strong;
+        break;
+      case NonNullableByDefaultCompiledMode.Agnostic:
+        flags = (flags | NonNullableByDefaultModeBit1Weak) |
+            NonNullableByDefaultModeBit2Strong;
+        break;
+    }
+  }
+
   String name;
 
   /// Problems in this [Library] encoded as json objects.

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 = 39;
+  static const int BinaryFormatVersion = 40;
 }
 
 abstract class ConstantTag {

pkg/kernel/test/binary/library_flags_test.dart

@@ -4,18 +4,72 @@
 
 import 'utils.dart';
 
-/// Test that library flags (external, synthetic)
-/// are serialized and read correctly.
+/// Test that library flags are serialized and read correctly.
 main() {
-  Library lib = new Library(Uri.parse("foo://bar.dart"));
-  lib.isSynthetic = false;
-  Library lib2 = libRoundTrip(lib);
-  if (lib2.isSynthetic != false)
-    throw "Serialized and re-read library had change in synthetic flag.";
-
-  lib = new Library(Uri.parse("foo://bar.dart"));
-  lib.isSynthetic = true;
-  lib2 = libRoundTrip(lib);
-  if (lib2.isSynthetic != true)
-    throw "Serialized and re-read library had change in synthetic flag.";
+  setSynthetic(Library lib, bool isSynthetic) {
+    lib.isSynthetic = isSynthetic;
+  }
+
+  verifySynthetic(Library lib, bool isSynthetic) {
+    if (lib.isSynthetic != isSynthetic) {
+      throw "Serialized and re-read library had change in synthetic flag.";
+    }
+  }
+
+  setNonNullableByDefault(Library lib, bool isNonNullableByDefault) {
+    lib.isNonNullableByDefault = isNonNullableByDefault;
+  }
+
+  verifyNonNullableByDefault(Library lib, bool isNonNullableByDefault) {
+    if (lib.isNonNullableByDefault != isNonNullableByDefault) {
+      throw "Serialized and re-read library had change in "
+          "isNonNullableByDefault flag.";
+    }
+  }
+
+  setNonNullableByDefaultCompiledMode(Library lib,
+      NonNullableByDefaultCompiledMode nonNullableByDefaultCompiledMode) {
+    lib.nonNullableByDefaultCompiledMode = nonNullableByDefaultCompiledMode;
+  }
+
+  verifyNonNullableByDefaultCompiledMode(Library lib,
+      NonNullableByDefaultCompiledMode nonNullableByDefaultCompiledMode) {
+    if (lib.nonNullableByDefaultCompiledMode !=
+        nonNullableByDefaultCompiledMode) {
+      throw "Serialized and re-read library had change in "
+          "nonNullableByDefaultCompiledMode flag.";
+    }
+  }
+
+  int combination = 0;
+  for (bool isSynthetic in [true, false]) {
+    for (bool isNonNullableByDefault in [true, false]) {
+      for (NonNullableByDefaultCompiledMode nonNullableByDefaultCompiledMode
+          in [
+        NonNullableByDefaultCompiledMode.Disabled,
+        NonNullableByDefaultCompiledMode.Weak,
+        NonNullableByDefaultCompiledMode.Strong,
+        NonNullableByDefaultCompiledMode.Agnostic,
+      ]) {
+        combination++;
+        print("Checking combination #$combination ("
+            "isSynthetic: $isSynthetic; "
+            "isNonNullableByDefault: $isNonNullableByDefault; "
+            "nonNullableByDefaultCompiledMode:"
+            " $nonNullableByDefaultCompiledMode");
+        Library lib = new Library(Uri.parse("foo://bar.dart"));
+        setSynthetic(lib, isSynthetic);
+        setNonNullableByDefault(lib, isNonNullableByDefault);
+        setNonNullableByDefaultCompiledMode(
+            lib, nonNullableByDefaultCompiledMode);
+        Library lib2 = libRoundTrip(lib);
+        verifySynthetic(lib2, isSynthetic);
+        verifyNonNullableByDefault(lib2, isNonNullableByDefault);
+        verifyNonNullableByDefaultCompiledMode(
+            lib2, nonNullableByDefaultCompiledMode);
+      }
+    }
+  }
+
+  print("Done: Everything looks good.");
 }

runtime/vm/compiler/frontend/kernel_translation_helper.h

@@ -763,6 +763,15 @@ class LibraryHelper {
     kExternal = 1 << 0,
     kSynthetic = 1 << 1,
     kIsNonNullableByDefault = 1 << 2,
+    kNonNullableByDefaultCompiledModeBit1Weak = 1 << 3,
+    kNonNullableByDefaultCompiledModeBit2Strong = 1 << 4,
+  };
+
+  enum NonNullableByDefaultCompiledMode {
+    kDisabled,
+    kWeak,
+    kStrong,
+    kAgnostic
   };
 
   explicit LibraryHelper(KernelReaderHelper* helper, uint32_t binary_version)
@@ -782,6 +791,14 @@ class LibraryHelper {
   bool IsNonNullableByDefault() const {
     return (flags_ & kIsNonNullableByDefault) != 0;
   }
+  NonNullableByDefaultCompiledMode GetNonNullableByDefaultCompiledMode() const {
+    bool weak = (flags_ & kNonNullableByDefaultCompiledModeBit1Weak) != 0;
+    bool strong = (flags_ & kNonNullableByDefaultCompiledModeBit2Strong) != 0;
+    if (weak && strong) return kAgnostic;
+    if (strong) return kStrong;
+    if (weak) return kWeak;
+    return kDisabled;
+  }
 
   uint8_t flags_ = 0;
   NameIndex canonical_name_;

runtime/vm/kernel_binary.h

@@ -20,7 +20,7 @@ static const uint32_t kMagicProgramFile = 0x90ABCDEFu;
 
 // Both version numbers are inclusive.
 static const uint32_t kMinSupportedKernelFormatVersion = 29;
-static const uint32_t kMaxSupportedKernelFormatVersion = 39;
+static const uint32_t kMaxSupportedKernelFormatVersion = 40;
 
 // Keep in sync with package:kernel/lib/binary/tag.dart
 #define KERNEL_TAG_LIST(V)                                                     \