Remove the flag --incompatible_restrict_string_escapes

This allows us to simplify the code and remove the options from the lexer and parser.

#8380

PiperOrigin-RevId: 404799093

src/main/java/com/google/devtools/build/lib/packages/semantics/BuildLanguageOptions.java

@@ -494,15 +494,6 @@ public class BuildLanguageOptions extends OptionsBase implements Serializable {
               + "returns a depset instead.")
   public boolean incompatibleDepsetForLibrariesToLinkGetter;
 
-  @Option(
-      name = "incompatible_restrict_string_escapes",
-      defaultValue = "true",
-      documentationCategory = OptionDocumentationCategory.STARLARK_SEMANTICS,
-      effectTags = {OptionEffectTag.BUILD_FILE_SEMANTICS},
-      metadataTags = {OptionMetadataTag.INCOMPATIBLE_CHANGE},
-      help = "If set to true, unknown string escapes like `\\a` become rejected.")
-  public boolean incompatibleRestrictStringEscapes;
-
   @Option(
       name = "incompatible_linkopts_to_linklibs",
       defaultValue = "true",
@@ -618,7 +609,6 @@ public StarlarkSemantics toStarlarkSemantics() {
                 INCOMPATIBLE_DEPSET_FOR_LIBRARIES_TO_LINK_GETTER,
                 incompatibleDepsetForLibrariesToLinkGetter)
             .setBool(INCOMPATIBLE_REQUIRE_LINKER_INPUT_CC_API, incompatibleRequireLinkerInputCcApi)
-            .setBool(INCOMPATIBLE_RESTRICT_STRING_ESCAPES, incompatibleRestrictStringEscapes)
             .setBool(INCOMPATIBLE_LINKOPTS_TO_LINKLIBS, incompatibleLinkoptsToLinklibs)
             .set(MAX_COMPUTATION_STEPS, maxComputationSteps)
             .set(NESTED_SET_DEPTH_LIMIT, nestedSetDepthLimit)
@@ -683,8 +673,6 @@ public StarlarkSemantics toStarlarkSemantics() {
       "-incompatible_no_rule_outputs_param";
   public static final String INCOMPATIBLE_REQUIRE_LINKER_INPUT_CC_API =
       "+incompatible_require_linker_input_cc_api";
-  public static final String INCOMPATIBLE_RESTRICT_STRING_ESCAPES =
-      "+incompatible_restrict_string_escapes";
   public static final String INCOMPATIBLE_RUN_SHELL_COMMAND_STRING =
       "+incompatible_run_shell_command_string";
   public static final String INCOMPATIBLE_STRUCT_HAS_NO_METHODS =

src/main/java/com/google/devtools/build/lib/skyframe/BzlCompileFunction.java

@@ -20,7 +20,6 @@
 import com.google.devtools.build.lib.events.Event;
 import com.google.devtools.build.lib.packages.BazelStarlarkEnvironment;
 import com.google.devtools.build.lib.packages.PackageFactory;
-import com.google.devtools.build.lib.packages.semantics.BuildLanguageOptions;
 import com.google.devtools.build.lib.vfs.FileSystemUtils;
 import com.google.devtools.build.lib.vfs.Path;
 import com.google.devtools.build.lib.vfs.RootedPath;
@@ -167,8 +166,6 @@ static BzlCompileValue computeInline(
             // statements whose bindings are intended to be visible in all BUILD
             // files. The loadBindsGlobally flag allows us to retrieve them.
             .loadBindsGlobally(key.isBuildPrelude())
-            .restrictStringEscapes(
-                semantics.getBool(BuildLanguageOptions.INCOMPATIBLE_RESTRICT_STRING_ESCAPES))
             .build();
     StarlarkFile file = StarlarkFile.parse(input, options);
 

src/main/java/com/google/devtools/build/lib/skyframe/PackageFunction.java

@@ -1456,8 +1456,6 @@ private CompiledBuildFile compileBuildFile(
             // as in .bzl files. One can always use a renaming load statement.
             .loadBindsGlobally(true)
             .allowToplevelRebinding(true)
-            .restrictStringEscapes(
-                semantics.getBool(BuildLanguageOptions.INCOMPATIBLE_RESTRICT_STRING_ESCAPES))
             .build();
 
     // parse

src/main/java/com/google/devtools/build/lib/skyframe/WorkspaceFileFunction.java

@@ -40,7 +40,6 @@
 import com.google.devtools.build.lib.packages.WorkspaceFactory;
 import com.google.devtools.build.lib.packages.WorkspaceFileValue;
 import com.google.devtools.build.lib.packages.WorkspaceFileValue.WorkspaceFileKey;
-import com.google.devtools.build.lib.packages.semantics.BuildLanguageOptions;
 import com.google.devtools.build.lib.rules.repository.RepositoryDelegatorFunction;
 import com.google.devtools.build.lib.rules.repository.ResolvedFileValue;
 import com.google.devtools.build.lib.server.FailureDetails.PackageLoading;
@@ -136,9 +135,6 @@ public SkyValue compute(SkyKey skyKey, Environment env)
             // WORKSPACE files followed BUILD norms, but this should
             // probably be flipped.
             .allowToplevelRebinding(true)
-            .restrictStringEscapes(
-                starlarkSemantics.getBool(
-                    BuildLanguageOptions.INCOMPATIBLE_RESTRICT_STRING_ESCAPES))
             .build();
 
     // Accumulate workspace files (prefix + main + suffix).

src/main/java/net/starlark/java/eval/Starlark.java

@@ -943,7 +943,7 @@ public static Object eval(
    */
   private static StarlarkFunction newExprFunction(
       ParserInput input, FileOptions options, Module module) throws SyntaxError.Exception {
-    Expression expr = Expression.parse(input, options);
+    Expression expr = Expression.parse(input);
     Program prog = Program.compileExpr(expr, module, options);
     Resolver.Function rfn = prog.getResolvedFunction();
     int[] globalIndex = module.getIndicesOfGlobals(rfn.getGlobals()); // see execFileProgram

src/main/java/net/starlark/java/syntax/Expression.java

@@ -56,15 +56,9 @@ public enum Kind {
    */
   public abstract Kind kind();
 
-  /** Parses an expression with the default options. */
-  public static Expression parse(ParserInput input) throws SyntaxError.Exception {
-    return parse(input, FileOptions.DEFAULT);
-  }
-
   /** Parses an expression. */
-  public static Expression parse(ParserInput input, FileOptions options)
-      throws SyntaxError.Exception {
-    return Parser.parseExpression(input, options);
+  public static Expression parse(ParserInput input) throws SyntaxError.Exception {
+    return Parser.parseExpression(input);
   }
 
 }

src/main/java/net/starlark/java/syntax/FileOptions.java

@@ -41,15 +41,6 @@ public abstract class FileOptions {
   /** The default options for Starlark static processing. New clients should use these defaults. */
   public static final FileOptions DEFAULT = builder().build();
 
-  // Options are presented in phase order: scanner, parser, resolver, compiler.
-
-  // --- scanner options ---
-
-  /** Disallow ineffective escape sequences such as {@code \a} when scanning string literals. */
-  public abstract boolean restrictStringEscapes();
-
-  // --- resolver options ---
-
   /**
    * During resolution, permit load statements to access private names such as {@code _x}. <br>
    * (Required for continued support of Bazel "WORKSPACE.resolved" files.)
@@ -82,7 +73,6 @@ public abstract class FileOptions {
   public static Builder builder() {
     // These are the DEFAULT values.
     return new AutoValue_FileOptions.Builder()
-        .restrictStringEscapes(true)
         .allowLoadPrivateSymbols(false)
         .allowToplevelRebinding(false)
         .loadBindsGlobally(false)
@@ -95,8 +85,6 @@ public static Builder builder() {
   @AutoValue.Builder
   public abstract static class Builder {
     // AutoValue why u make me say it 3 times?
-    public abstract Builder restrictStringEscapes(boolean value);
-
     public abstract Builder allowLoadPrivateSymbols(boolean value);
 
     public abstract Builder allowToplevelRebinding(boolean value);

src/main/java/net/starlark/java/syntax/Lexer.java

@@ -54,8 +54,6 @@ final class Lexer {
   private final char[] buffer;
   private int pos;
 
-  private final FileOptions options;
-
   // The stack of enclosing indentation levels in spaces.
   // The first (outermost) element is always zero.
   private final Stack<Integer> indentStack = new Stack<>();
@@ -93,9 +91,8 @@ final class Lexer {
 
   // Constructs a lexer which tokenizes the parser input.
   // Errors are appended to errors.
-  Lexer(ParserInput input, FileOptions options, List<SyntaxError> errors) {
+  Lexer(ParserInput input, List<SyntaxError> errors) {
     this.locs = FileLocations.create(input.getContent(), input.getFile());
-    this.options = options;
     this.buffer = input.getContent();
     this.pos = 0;
     this.errors = errors;
@@ -362,20 +359,9 @@ private void escapedStringLiteral(char quot, boolean isRaw) {
             case 'u':
             case 'U':
             case 'v':
-            case 'x':
-              // exists in Python but not implemented in Blaze => error
-              error("invalid escape sequence: \\" + c, pos - 1);
-              break;
             default:
               // unknown char escape => "\literal"
-              if (options.restrictStringEscapes()) {
-                error(
-                    "invalid escape sequence: \\"
-                        + c
-                        + ". You can enable unknown escape sequences by passing the flag"
-                        + " --incompatible_restrict_string_escapes=false",
-                    pos - 1);
-              }
+              error("invalid escape sequence: \\" + c + ". Use '\\\\' to insert '\\'.", pos - 1);
               literal.append('\\');
               literal.append(c);
               break;

src/main/java/net/starlark/java/syntax/Parser.java

@@ -171,9 +171,9 @@ private static String tokenString(TokenKind kind, @Nullable Object value) {
   }
 
   // Main entry point for parsing a file.
-  static ParseResult parseFile(ParserInput input, FileOptions options) {
+  static ParseResult parseFile(ParserInput input) {
     List<SyntaxError> errors = new ArrayList<>();
-    Lexer lexer = new Lexer(input, options, errors);
+    Lexer lexer = new Lexer(input, errors);
     Parser parser = new Parser(lexer, errors);
 
     StarlarkFile.ParseProfiler profiler = Parser.profiler;
@@ -207,10 +207,9 @@ private void parseStatement(ImmutableList.Builder<Statement> list) {
   }
 
   /** Parses an expression, possibly followed by newline tokens. */
-  static Expression parseExpression(ParserInput input, FileOptions options)
-      throws SyntaxError.Exception {
+  static Expression parseExpression(ParserInput input) throws SyntaxError.Exception {
     List<SyntaxError> errors = new ArrayList<>();
-    Lexer lexer = new Lexer(input, options, errors);
+    Lexer lexer = new Lexer(input, errors);
     Parser parser = new Parser(lexer, errors);
     Expression result = null;
     try {

src/main/java/net/starlark/java/syntax/StarlarkFile.java

@@ -134,7 +134,7 @@ public Resolver.Function getResolvedFunction() {
    * </pre>
    */
   public static StarlarkFile parse(ParserInput input, FileOptions options) {
-    Parser.ParseResult result = Parser.parseFile(input, options);
+    Parser.ParseResult result = Parser.parseFile(input);
     return new StarlarkFile(
         result.locs, result.statements, options, result.comments, result.errors);
   }

src/main/java/net/starlark/java/syntax/StringLiteral.java

@@ -81,7 +81,7 @@ public static String unquote(String s) {
     // independent of the Lexer, which should only validate string literals
     // but not unquote them. Clients (e.g. the compiler) can unquote on demand.
     ArrayList<SyntaxError> errors = new ArrayList<>();
-    Lexer lexer = new Lexer(ParserInput.fromLines(s), FileOptions.DEFAULT, errors);
+    Lexer lexer = new Lexer(ParserInput.fromLines(s), errors);
     lexer.nextToken();
     if (!errors.isEmpty()) {
       throw new IllegalArgumentException(errors.get(0).message());

src/test/java/com/google/devtools/build/lib/packages/semantics/ConsistencyTest.java

@@ -147,7 +147,6 @@ private static BuildLanguageOptions buildRandomOptions(Random rand) throws Excep
         "--incompatible_struct_has_no_methods=" + rand.nextBoolean(),
         "--incompatible_visibility_private_attributes_at_definition=" + rand.nextBoolean(),
         "--incompatible_require_linker_input_cc_api=" + rand.nextBoolean(),
-        "--incompatible_restrict_string_escapes=" + rand.nextBoolean(),
         "--incompatible_use_cc_configure_from_rules_cc=" + rand.nextBoolean(),
         "--internal_starlark_flag_test_canary=" + rand.nextBoolean(),
         "--max_computation_steps=" + rand.nextLong());
@@ -197,7 +196,6 @@ private static StarlarkSemantics buildRandomSemantics(Random rand) {
             BuildLanguageOptions.INCOMPATIBLE_VISIBILITY_PRIVATE_ATTRIBUTES_AT_DEFINITION,
             rand.nextBoolean())
         .setBool(BuildLanguageOptions.INCOMPATIBLE_REQUIRE_LINKER_INPUT_CC_API, rand.nextBoolean())
-        .setBool(BuildLanguageOptions.INCOMPATIBLE_RESTRICT_STRING_ESCAPES, rand.nextBoolean())
         .setBool(
             BuildLanguageOptions.INCOMPATIBLE_USE_CC_CONFIGURE_FROM_RULES_CC, rand.nextBoolean())
         .setBool(StarlarkSemantics.PRINT_TEST_MARKER, rand.nextBoolean())

src/test/java/com/google/devtools/build/lib/starlark/StarlarkIntegrationTest.java

@@ -3387,8 +3387,6 @@ public void testDictGetUnhashableForbidden() throws Exception {
 
   @Test
   public void testUnknownStringEscapesForbidden() throws Exception {
-    setBuildLanguageOptions("--incompatible_restrict_string_escapes=true");
-
     scratch.file("test/extension.bzl", "y = \"\\z\"");
 
     scratch.file("test/BUILD", "load('//test:extension.bzl', 'y')", "cc_library(name = 'r')");
@@ -3398,17 +3396,6 @@ public void testUnknownStringEscapesForbidden() throws Exception {
     assertContainsEvent("invalid escape sequence: \\z");
   }
 
-  @Test
-  public void testUnknownStringEscapes() throws Exception {
-    setBuildLanguageOptions("--incompatible_restrict_string_escapes=false");
-
-    scratch.file("test/extension.bzl", "y = \"\\z\"");
-
-    scratch.file("test/BUILD", "load('//test:extension.bzl', 'y')", "cc_library(name = 'r')");
-
-    getConfiguredTarget("//test:r");
-  }
-
   @Test
   public void testSplitEmptySeparatorForbidden() throws Exception {
     scratch.file("test/extension.bzl", "y = 'abc'.split('')");

src/test/java/net/starlark/java/syntax/LexerTest.java

@@ -41,7 +41,7 @@ public class LexerTest {
   private Lexer createLexer(String input) {
     ParserInput inputSource = ParserInput.fromString(input, "");
     errors.clear();
-    return new Lexer(inputSource, FileOptions.DEFAULT, errors);
+    return new Lexer(inputSource, errors);
   }
 
   private static class Token {
@@ -357,18 +357,16 @@ public void testStringEscapes() throws Exception {
     checkErrors(
         "'x\\hx'", //
         "STRING(x\\hx) NEWLINE EOF",
-        "   ^ invalid escape sequence: \\h. You can enable unknown escape sequences by passing the"
-            + " flag --incompatible_restrict_string_escapes=false");
+        "   ^ invalid escape sequence: \\h. Use '\\\\' to insert '\\'.");
     checkErrors(
         "'\\$$'", //
         "STRING(\\$$) NEWLINE EOF",
-        "  ^ invalid escape sequence: \\$. You can enable unknown escape sequences by passing the"
-            + " flag --incompatible_restrict_string_escapes=false");
+        "  ^ invalid escape sequence: \\$. Use '\\\\' to insert '\\'.");
     check("'a\\\nb'", "STRING(ab) NEWLINE EOF"); // escape end of line
     checkErrors(
         "\"ab\\ucd\"", //
-        "STRING(abcd) NEWLINE EOF",
-        "    ^ invalid escape sequence: \\u");
+        "STRING(ab\\ucd) NEWLINE EOF",
+        "    ^ invalid escape sequence: \\u. Use '\\\\' to insert '\\'.");
   }
 
   @Test
@@ -645,10 +643,7 @@ public void testStringLiteralUnquote() {
     assertUnquoteError("'", "unclosed string literal");
     assertUnquoteError("\"", "unclosed string literal");
     assertUnquoteError("'abc", "unclosed string literal");
-    assertUnquoteError(
-        "'\\g'",
-        "invalid escape sequence: \\g. You can enable unknown escape sequences by passing the flag"
-            + " --incompatible_restrict_string_escapes=false"); // this temporary hint is a lie
+    assertUnquoteError("'\\g'", "invalid escape sequence: \\g. Use '\\\\' to insert '\\'.");
   }
 
   private static void assertUnquoteEquals(String literal, String value) {

src/test/java/net/starlark/java/syntax/NodePrinterTest.java

@@ -396,7 +396,7 @@ public void comment() throws SyntaxError.Exception {
         ParserInput.fromLines(
             "# foo", //
             "expr # bar");
-    Parser.ParseResult r = Parser.parseFile(input, FileOptions.DEFAULT);
+    Parser.ParseResult r = Parser.parseFile(input);
     Comment c0 = r.comments.get(0);
     assertIndentedPrettyMatches(c0, "  # foo");
     assertTostringMatches(c0, "# foo");