[9.0.1] Refactor flag aliases to be passed around as labels

src/main/java/com/google/devtools/build/lib/analysis/config/BuildConfigurationValue.java

@@ -14,7 +14,6 @@
 
 package com.google.devtools.build.lib.analysis.config;
 
-import static com.google.common.collect.ImmutableMap.toImmutableMap;
 
 import com.google.common.annotations.VisibleForTesting;
 import com.google.common.base.Joiner;
@@ -941,11 +940,6 @@ public List<Label> getTargetEnvironments() {
     return options.targetEnvironments;
   }
 
-  public ImmutableMap<String, String> getCommandLineFlagAliases() {
-    return options.commandLineFlagAliases.stream()
-        .collect(toImmutableMap(Map.Entry::getKey, Map.Entry::getValue));
-  }
-
   @Nullable
   public Class<? extends Fragment> getStarlarkFragmentByName(String name) {
     return starlarkVisibleFragments.get(name);

src/main/java/com/google/devtools/build/lib/analysis/config/CoreOptionConverters.java

@@ -22,6 +22,7 @@
 import static com.google.devtools.build.lib.packages.Type.STRING;
 import static com.google.devtools.build.lib.packages.Types.STRING_LIST;
 import static com.google.devtools.build.lib.packages.Types.STRING_SET;
+import static com.google.devtools.common.options.OptionsParser.STARLARK_SKIPPED_PREFIXES;
 import static java.util.stream.Collectors.joining;
 
 import com.google.common.base.Preconditions;
@@ -47,6 +48,7 @@
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
+import java.util.regex.Pattern;
 import javax.annotation.Nullable;
 import net.starlark.java.eval.StarlarkInt;
 import net.starlark.java.eval.StarlarkValue;
@@ -57,6 +59,13 @@
  */
 public class CoreOptionConverters {
 
+  /**
+   * The name of the flag used for shorthand aliasing in blaze. {@link
+   * com.google.devtools.build.lib.analysis.config.CoreOptions#commandLineFlagAliases} for the
+   * option definition.
+   */
+  public static final String BLAZE_ALIASING_FLAG = "flag_alias";
+
   // Not instantiable.
   private CoreOptionConverters() {}
 
@@ -350,4 +359,49 @@ private static Label convertOptionsLabel(String input, @Nullable Object conversi
       throw new OptionsParsingException(e.getMessage());
     }
   }
+
+  /**
+   * A converter for command line flag aliases. It does additional validation on the name and value
+   * of the assignment to ensure they conform to the naming limitations.
+   */
+  public static class FlagAliasConverter implements Converter<Map.Entry<String, Label>> {
+
+    @Override
+    public Map.Entry<String, Label> convert(String input, @Nullable Object conversionContext)
+        throws OptionsParsingException {
+      int pos = input.indexOf("=");
+      if (pos <= 0) {
+        throw new OptionsParsingException(
+            "Flag alias definitions must be in the form of a 'name=label' assignment");
+      }
+      String shortForm = input.substring(0, pos);
+      String longForm = input.substring(pos + 1);
+
+      String cmdLineAlias = "--" + BLAZE_ALIASING_FLAG + "=" + input;
+
+      if (!Pattern.matches("\\w*", shortForm)) {
+        throw new OptionsParsingException(
+            shortForm + " should only consist of word characters to be a valid alias name.",
+            cmdLineAlias);
+      }
+      if (longForm.contains("=")) {
+        throw new OptionsParsingException(
+            "--" + BLAZE_ALIASING_FLAG + " does not support flag value assignment.", cmdLineAlias);
+      }
+
+      // Remove this check if native options are permitted to be aliased
+      String longFormWithDashes = "--" + longForm;
+      if (STARLARK_SKIPPED_PREFIXES.stream().noneMatch(longFormWithDashes::startsWith)) {
+        throw new OptionsParsingException(
+            "--" + BLAZE_ALIASING_FLAG + " only supports Starlark build settings.", cmdLineAlias);
+      }
+
+      return Maps.immutableEntry(shortForm, convertOptionsLabel(longForm, conversionContext));
+    }
+
+    @Override
+    public String getTypeDescription() {
+      return "a 'name=label' flag alias";
+    }
+  }
 }

src/main/java/com/google/devtools/build/lib/analysis/config/CoreOptions.java

@@ -16,6 +16,7 @@
 
 import static com.google.common.collect.ImmutableList.toImmutableList;
 import static com.google.common.collect.ImmutableMap.toImmutableMap;
+import static java.util.Map.Entry.comparingByKey;
 
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
@@ -36,7 +37,6 @@
 import com.google.devtools.common.options.OptionsParsingException;
 import com.google.devtools.common.options.TriState;
 import java.util.ArrayList;
-import java.util.Comparator;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
@@ -1059,7 +1059,7 @@ public OutputPathsConverter() {
 
   @Option(
       name = "flag_alias",
-      converter = Converters.FlagAliasConverter.class,
+      converter = CoreOptionConverters.FlagAliasConverter.class,
       defaultValue = "null",
       allowMultiple = true,
       documentationCategory = OptionDocumentationCategory.GENERIC_INPUTS,
@@ -1070,7 +1070,7 @@ public OutputPathsConverter() {
           Sets a shorthand name for a Starlark flag. It takes a single key-value pair in the form
           `{key}={value}` as an argument.
           """)
-  public List<Map.Entry<String, String>> commandLineFlagAliases;
+  public List<Map.Entry<String, Label>> commandLineFlagAliases;
 
   @Option(
       name = "archived_tree_artifact_mnemonics_filter",
@@ -1155,6 +1155,20 @@ public boolean usePlatformInOutputDir(Label platform) {
     return false;
   }
 
+  private volatile ImmutableMap<String, Label> commandLineFlagAliasesMap = null;
+
+  public ImmutableMap<String, Label> getCommandLineFlagAliases() {
+    // Force a single copy of the map to avoid repeated conversions.
+    if (commandLineFlagAliasesMap == null) {
+      synchronized (this) {
+        if (commandLineFlagAliasesMap == null) {
+          commandLineFlagAliasesMap = ImmutableMap.copyOf(commandLineFlagAliases);
+        }
+      }
+    }
+    return commandLineFlagAliasesMap;
+  }
+
   /** Ways configured targets may provide the {@link Fragment}s they require. */
   public enum IncludeConfigFragmentsEnum implements StarlarkValue {
     /**
@@ -1183,10 +1197,9 @@ public ImmutableMap<String, String> getNormalizedCommandLineBuildVariables() {
   }
 
   // Sort the map entries by key.
-  private static List<Map.Entry<String, String>> sortEntries(
-      List<Map.Entry<String, String>> entries) {
-    ImmutableList<Map.Entry<String, String>> sortedEntries =
-        entries.stream().sorted(Comparator.comparing(Map.Entry::getKey)).collect(toImmutableList());
+  private static <V> List<Map.Entry<String, V>> sortEntries(List<Map.Entry<String, V>> entries) {
+    ImmutableList<Map.Entry<String, V>> sortedEntries =
+        entries.stream().sorted(comparingByKey()).collect(toImmutableList());
     // If we made no changes, return the same instance we got to reduce churn.
     if (sortedEntries.equals(entries)) {
       return entries;
@@ -1243,4 +1256,13 @@ public CoreOptions getNormalized() {
 
     return result;
   }
+
+  @Override
+  public CoreOptions clone() {
+    CoreOptions base = (CoreOptions) super.clone();
+    // commandLineFlagAliasesMap is derived from commandLineFlagAliases, so it must be cleared
+    // here to ensure it is recomputed in case commandLineFlagAliases is mutated after cloning.
+    base.commandLineFlagAliasesMap = null;
+    return base;
+  }
 }

src/main/java/com/google/devtools/build/lib/analysis/config/FragmentOptions.java

@@ -97,10 +97,10 @@ protected static ImmutableList<String> dedupAndSort(@Nullable List<String> value
    * Helper method for subclasses to normalize list of map entries by keeping only the last entry
    * for each key. The order of the entries is preserved.
    */
-  protected static List<Map.Entry<String, String>> normalizeEntries(
-      List<Map.Entry<String, String>> entries) {
-    LinkedHashMap<String, String> normalizedEntries = new LinkedHashMap<>();
-    for (Map.Entry<String, String> entry : entries) {
+  protected static <V> List<Map.Entry<String, V>> normalizeEntries(
+      List<Map.Entry<String, V>> entries) {
+    LinkedHashMap<String, V> normalizedEntries = new LinkedHashMap<>();
+    for (Map.Entry<String, V> entry : entries) {
       normalizedEntries.put(entry.getKey(), entry.getValue());
     }
     // If we made no changes, return the same instance we got to reduce churn.