Target pattern parsing cleanup

================

* `TargetPattern#renameRepository` is merged into `TargetPattern.Parser#parse`. This is much less error-prone -- repo mapping should not be an afterthought, but something that should always be applied if possible (sometimes it's not, for example for `blaze query`).
  * This also fixes the bug where calling `native.register_toolchains("//:all")` in `@some_repo//:defs.bzl` registers `@//:all` instead of `@some_repo//:all` (see change in RegisteredExecutionPlatformsTest)
* A new class `SignedTargetPattern` is introduced, which can store whether the pattern is positive or negative (with the `sign` method).
* `TargetPatternValue#keys` is greatly simplified thanks to the changes above; the exception throwing is confined to the parsing step, and the construction of `TargetPatternKey` can happen as a separate step, obviating the whole "skykey or exception" dance.
* Following from the above, the //external package now stores registered toolchains and execution platforms as parsed target patterns, instead of simple strings.

Among other things, this would help implement toolchain registration in bzlmod.

PiperOrigin-RevId: 400720457

src/main/java/com/google/devtools/build/lib/bazel/commands/SyncCommand.java

@@ -13,6 +13,8 @@
 // limitations under the License.
 package com.google.devtools.build.lib.bazel.commands;
 
+import static com.google.common.collect.ImmutableList.toImmutableList;
+
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.ImmutableSet;
@@ -24,6 +26,7 @@
 import com.google.devtools.build.lib.cmdline.LabelConstants;
 import com.google.devtools.build.lib.cmdline.LabelSyntaxException;
 import com.google.devtools.build.lib.cmdline.RepositoryName;
+import com.google.devtools.build.lib.cmdline.TargetPattern;
 import com.google.devtools.build.lib.events.Event;
 import com.google.devtools.build.lib.events.ExtendedEventHandler.ResolvedEvent;
 import com.google.devtools.build.lib.packages.Rule;
@@ -166,12 +169,17 @@ public BlazeCommandResult exec(CommandEnvironment env, OptionsParsingResult opti
       env.getReporter()
           .post(
               genericArgsCall(
-                  "register_toolchains", fileValue.getPackage().getRegisteredToolchains()));
+                  "register_toolchains",
+                  fileValue.getPackage().getRegisteredToolchains().stream()
+                      .map(TargetPattern::getOriginalPattern)
+                      .collect(toImmutableList())));
       env.getReporter()
           .post(
               genericArgsCall(
                   "register_execution_platforms",
-                  fileValue.getPackage().getRegisteredExecutionPlatforms()));
+                  fileValue.getPackage().getRegisteredExecutionPlatforms().stream()
+                      .map(TargetPattern::getOriginalPattern)
+                      .collect(toImmutableList())));
       env.getReporter().post(new RepositoryOrderEvent(repositoryOrder.build()));
 
       // take all Starlark workspace rules and get their values

src/main/java/com/google/devtools/build/lib/buildtool/AnalysisAndExecutionPhaseRunner.java

@@ -228,7 +228,7 @@ private static ImmutableSet<String> getExplicitTargetPatterns(
       CommandEnvironment env, List<String> requestedTargetPatterns)
       throws ViewCreationFailedException {
     ImmutableSet.Builder<String> explicitTargetPatterns = ImmutableSet.builder();
-    TargetPattern.Parser parser = new TargetPattern.Parser(env.getRelativeWorkingDirectory());
+    TargetPattern.Parser parser = TargetPattern.mainRepoParser(env.getRelativeWorkingDirectory());
 
     for (String requestedTargetPattern : requestedTargetPatterns) {
       if (requestedTargetPattern.startsWith("-")) {

src/main/java/com/google/devtools/build/lib/buildtool/AnalysisPhaseRunner.java

@@ -315,7 +315,7 @@ private static ImmutableSet<String> getExplicitTargetPatterns(
       CommandEnvironment env, List<String> requestedTargetPatterns)
       throws ViewCreationFailedException {
     ImmutableSet.Builder<String> explicitTargetPatterns = ImmutableSet.builder();
-    TargetPattern.Parser parser = new TargetPattern.Parser(env.getRelativeWorkingDirectory());
+    TargetPattern.Parser parser = TargetPattern.mainRepoParser(env.getRelativeWorkingDirectory());
 
     for (String requestedTargetPattern : requestedTargetPatterns) {
       if (requestedTargetPattern.startsWith("-")) {

src/main/java/com/google/devtools/build/lib/cmdline/BUILD

@@ -16,6 +16,7 @@ java_library(
         "LabelConstants.java",
         "LabelSerializationProxy.java",
         "ResolvedTargets.java",
+        "SignedTargetPattern.java",
         "TargetParsingException.java",
         "TargetPattern.java",
         "TargetPatternResolver.java",
@@ -38,6 +39,7 @@ java_library(
         "//src/main/java/net/starlark/java/annot",
         "//src/main/java/net/starlark/java/eval",
         "//src/main/protobuf:failure_details_java_proto",
+        "//third_party:auto_value",
         "//third_party:error_prone_annotations",
         "//third_party:guava",
         "//third_party:jsr305",

src/main/java/com/google/devtools/build/lib/cmdline/SignedTargetPattern.java

@@ -0,0 +1,44 @@
+// Copyright 2021 The Bazel Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package com.google.devtools.build.lib.cmdline;
+
+import com.google.auto.value.AutoValue;
+
+/** A {@link TargetPattern} with a potential minus sign in front of it, signifying exclusion. */
+@AutoValue
+public abstract class SignedTargetPattern {
+  public abstract TargetPattern pattern();
+
+  public abstract Sign sign();
+
+  public static SignedTargetPattern create(TargetPattern pattern, Sign sign) {
+    return new AutoValue_SignedTargetPattern(pattern, sign);
+  }
+
+  /** Whether this target pattern begins with a minus sign (NEGATIVE) or not (POSITIVE). */
+  public enum Sign {
+    POSITIVE,
+    NEGATIVE
+  }
+
+  public static SignedTargetPattern parse(String pattern, TargetPattern.Parser parser)
+      throws TargetParsingException {
+    if (pattern.startsWith("-")) {
+      return create(parser.parse(pattern.substring(1)), SignedTargetPattern.Sign.NEGATIVE);
+    } else {
+      return create(parser.parse(pattern), SignedTargetPattern.Sign.POSITIVE);
+    }
+  }
+}