Fix query command suggestion in error message with repo mappings

The package label in the query command suggested when a specified target
isn't found in a packge looked like `@rules_cc~1.0.0//pkg`, which
doesn't work as the repo name is canonical, but the label isn't.

This is fixed by reusing the logic from
`Label#getUnambiguousCanonicalForm`.

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

@@ -416,9 +416,7 @@ public String getCanonicalForm() {
    * Label.parse*(x.getUnambiguousCanonicalForm(), ...).equals(x)}).
    */
   public String getUnambiguousCanonicalForm() {
-    return String.format(
-        "@@%s//%s:%s",
-        packageIdentifier.getRepository().getName(), packageIdentifier.getPackageFragment(), name);
+    return packageIdentifier.getUnambiguousCanonicalForm() + ":" + name;
   }
 
   /** Return the name of the repository label refers to without the leading `at` symbol. */

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

@@ -177,6 +177,15 @@ public String getCanonicalForm() {
     return repository.getCanonicalForm() + "//" + getPackageFragment();
   }
 
+  /**
+   * Returns an absolutely unambiguous canonical form for this package in label form. Parsing this
+   * string in any environment, even when subject to repository mapping, should identify the same
+   * package.
+   */
+  public String getUnambiguousCanonicalForm() {
+    return String.format("@@%s//%s", getRepository().getName(), getPackageFragment());
+  }
+
   /**
    * Returns the package path, possibly qualified with a repository name.
    *

src/main/java/com/google/devtools/build/lib/packages/Package.java

@@ -731,7 +731,7 @@ private String getAlternateTargetSuggestion(String targetName) {
       String blazeQuerySuggestion =
           String.format(
               "Tip: use `query %s:*` to see all the targets in that package",
-              packageIdentifier.getCanonicalForm());
+              packageIdentifier.getUnambiguousCanonicalForm());
       return String.format(
           " (%s)", Joiner.on(" ").skipNulls().join(targetSuggestion, blazeQuerySuggestion));
     }

src/test/java/com/google/devtools/build/lib/analysis/BuildViewTest.java

@@ -699,8 +699,8 @@ public void testHelpfulErrorForWrongPackageLabels() throws Exception {
     assertThat(result.hasError()).isTrue();
     assertContainsEvent(
         "no such target '//x:z': target 'z' not declared in package 'x' defined by"
-            + " /workspace/x/BUILD (Tip: use `query //x:*` to see all the targets in that package)"
-            + " and referenced by '//y:y'");
+            + " /workspace/x/BUILD (Tip: use `query @@//x:*` to see all the targets in that"
+            + " package) and referenced by '//y:y'");
   }
 
   @Test

src/test/java/com/google/devtools/build/lib/packages/PackageFactoryTest.java

@@ -284,7 +284,7 @@ public void testCreationOfInputFiles() throws Exception {
         .hasMessageThat()
         .isEqualTo(
             "no such target '//foo:A': target 'A' not declared in package 'foo' defined by"
-                + " /workspace/foo/BUILD (Tip: use `query //foo:*` to see all the targets in that"
+                + " /workspace/foo/BUILD (Tip: use `query @@//foo:*` to see all the targets in that"
                 + " package)");
 
     // These are the only input files: BUILD, Z
@@ -423,8 +423,8 @@ public void testHelpfulErrorForMissingExportsFiles() throws Exception {
         .hasMessageThat()
         .isEqualTo(
             "no such target '//x:z.cc': target 'z.cc' not declared in package 'x' defined by"
-                + " /workspace/x/BUILD (did you mean 'x.cc'? Tip: use `query //x:*` to see all the"
-                + " targets in that package)");
+                + " /workspace/x/BUILD (did you mean 'x.cc'? Tip: use `query @@//x:*` to see all"
+                + " the targets in that package)");
 
     e = assertThrows(NoSuchTargetException.class, () -> pkg.getTarget("dir"));
     assertThat(e)

src/test/java/com/google/devtools/build/lib/pkgcache/CompileOneDependencyTransformerTest.java

@@ -160,8 +160,8 @@ public void testCompileOneDepOnMissingFile() throws Exception {
         .hasMessageThat()
         .isEqualTo(
             "no such target '//foo:missing.cc': target 'missing.cc' not declared in package "
-                + "'foo' defined by /workspace/foo/BUILD (Tip: use `query //foo:*` to see all the "
-                + "targets in that package)");
+                + "'foo' defined by /workspace/foo/BUILD (Tip: use `query @@//foo:*` to see all "
+                + "the targets in that package)");
 
     // Also, try a valid input file which has no dependent rules in its package.
     e = assertThrows(TargetParsingException.class, () -> parseCompileOneDep("//foo:baz/bang"));

src/test/java/com/google/devtools/build/lib/pkgcache/PackageLoadingTest.java

@@ -237,7 +237,7 @@ public void testGetNonexistentTarget() throws Exception {
         .isEqualTo(
             "no such target '//pkg1:not-there': target 'not-there' "
                 + "not declared in package 'pkg1' defined by /workspace/pkg1/BUILD (Tip: use "
-                + "`query //pkg1:*` to see all the targets in that package)");
+                + "`query @@//pkg1:*` to see all the targets in that package)");
   }
 
   /**

src/test/java/com/google/devtools/build/lib/query2/testutil/AbstractQueryTest.java

@@ -290,7 +290,7 @@ protected final void checkResultOfTargetLiteralWithMissingTargets(
             "no such target '//a:b': target 'b' not declared in package 'a' "
                 + "defined by "
                 + helper.getRootDirectory().getPathString()
-                + "/a/BUILD (Tip: use `query //a:*` to see all the targets in that package)");
+                + "/a/BUILD (Tip: use `query @@//a:*` to see all the targets in that package)");
     assertThat(failureDetail.getPackageLoading().getCode())
         .isEqualTo(FailureDetails.PackageLoading.Code.TARGET_MISSING);
   }