Add an exec_tools attribute for genrule, which allows specifying tool…

…s that should be configured with the execution transition, instead of the host transition.

Note that this attribute is for migration from host to execution configurations, and will eventually be deprecated and removed once that migration is complete.

PiperOrigin-RevId: 251867407

src/main/java/com/google/devtools/build/lib/rules/genrule/GenRuleBase.java

@@ -217,6 +217,7 @@ public String toString() {
   protected CommandHelper.Builder commandHelperBuilder(RuleContext ruleContext) {
     return CommandHelper.builder(ruleContext)
         .addHostToolDependencies("tools")
+        .addToolDependencies("exec_tools")
         .addHostToolDependencies("toolchains");
   }
 

src/main/java/com/google/devtools/build/lib/rules/genrule/GenRuleBaseRule.java

@@ -23,6 +23,7 @@
 import com.google.devtools.build.lib.analysis.BaseRuleClasses;
 import com.google.devtools.build.lib.analysis.RuleDefinition;
 import com.google.devtools.build.lib.analysis.RuleDefinitionEnvironment;
+import com.google.devtools.build.lib.analysis.config.ExecutionTransitionFactory;
 import com.google.devtools.build.lib.analysis.config.HostTransition;
 import com.google.devtools.build.lib.packages.Attribute;
 import com.google.devtools.build.lib.packages.AttributeMap;
@@ -84,6 +85,29 @@ public RuleClass build(
             attr("tools", LABEL_LIST)
                 .cfg(HostTransition.createFactory())
                 .allowedFileTypes(FileTypeSet.ANY_FILE))
+
+        /* <!-- #BLAZE_RULE(genrule).ATTRIBUTE(exec_tools) -->
+        A list of <i>tool</i> dependencies for this rule. This behaves exactly like the
+        <a href="#genrule.tools"><code>tools</code></a> attribute, except that these dependencies
+        will be configured for the rule's execution platform instead of the host configuration.
+        This means that dependencies in <code>exec_tools</code> are not subject to the same
+        limitations as dependencies in <code>tools</code>. In particular, they are not required to
+        use the host configuration for their own transitive dependencies. See
+        <a href="#genrule.tools"><code>tools</code></a> for further details.
+
+        <p>
+          Note that eventually the host configuration will be replaced by the execution
+          configuration. When that happens, this attribute will be deprecated in favor of
+          <code>tools</code>. Until then, this attribute allows users to selectively migrate
+          dependencies to the execution configuration.
+        </p>
+        <!-- #END_BLAZE_RULE.ATTRIBUTE --> */
+        .add(
+            attr("exec_tools", LABEL_LIST)
+                .cfg(new ExecutionTransitionFactory())
+                .allowedFileTypes(FileTypeSet.ANY_FILE)
+                .dontCheckConstraints())
+
         /* <!-- #BLAZE_RULE(genrule).ATTRIBUTE(outs) -->
         A list of files generated by this rule.
         <p>

src/test/java/com/google/devtools/build/lib/bazel/rules/genrule/GenRuleConfiguredTargetTest.java

@@ -614,4 +614,24 @@ public void testDuplicateLocalFlags() throws Exception {
     getConfiguredTarget("//foo:g");
     assertNoEvents();
   }
+
+  @Test
+  public void testExecToolsAreExecConfiguration() throws Exception {
+    scratch.file(
+        "config/BUILD",
+        "genrule(name='src', outs=['src.out'], cmd=':')",
+        "genrule(name='exec_tool', outs=['exec_tool.out'], cmd=':')",
+        "genrule(name='config', ",
+        "        srcs=[':src'], exec_tools=[':exec_tool'], outs=['out'],",
+        "        cmd='$(location :exec_tool)')");
+
+    ConfiguredTarget parentTarget = getConfiguredTarget("//config");
+
+    // Cannot use getDirectPrerequisites, as this re-configures that target incorrectly.
+    Artifact out = Iterables.getFirst(getFilesToBuild(parentTarget), null);
+    assertThat(getGeneratingAction(out).getTools()).hasSize(1);
+    Artifact execTool = getOnlyElement(getGeneratingAction(out).getTools());
+    // This is the output dir fragment for the execution transition.
+    assertThat(execTool.getExecPathString()).contains("-exec-");
+  }
 }