Change Skylark's print() on a rule target to print the Skylark-exposed provider keys.

This change only affects printing a rule target directly -- it intentionally does not affect the behavior of str(target), as we want to avoid skylark code being able to parse potentially-private provider keys.

RELNOTES: In skylark, print(target) now shows the provider keys of a target, as debug information.
PiperOrigin-RevId: 186046226

1 files changed, 40 insertions, 0 deletions

diff --git a/src/test/java/com/google/devtools/build/lib/skylark/SkylarkIntegrationTest.java b/src/test/java/com/google/devtools/build/lib/skylark/SkylarkIntegrationTest.java
index 6f8e3843b0..8764ac499e 100644
--- a/src/test/java/com/google/devtools/build/lib/skylark/SkylarkIntegrationTest.java
+++ b/src/test/java/com/google/devtools/build/lib/skylark/SkylarkIntegrationTest.java
@@ -916,6 +916,46 @@ public class SkylarkIntegrationTest extends BuildViewTestCase {
   }
 
   @Test
+  public void testPrintProviderCollection() throws Exception {
+    scratch.file(
+        "test/skylark/rules.bzl",
+        "",
+        "FooInfo = provider()",
+        "BarInfo = provider()",
+        "",
+        "def _top_level_rule_impl(ctx):",
+        "  print('My Dep Providers:', ctx.attr.my_dep)",
+        "",
+        "def _dep_rule_impl(name):",
+        "  providers = [",
+        "      FooInfo(),",
+        "      BarInfo(),",
+        "  ]",
+        "  return providers",
+        "",
+        "top_level_rule = rule(",
+        "    implementation=_top_level_rule_impl,",
+        "    attrs={'my_dep':attr.label()}",
+        ")",
+        "",
+        "dep_rule = rule(",
+        "    implementation=_dep_rule_impl,",
+        ")");
+
+    scratch.file(
+        "test/skylark/BUILD",
+        "load('//test/skylark:rules.bzl', 'top_level_rule', 'dep_rule')",
+        "",
+        "top_level_rule(name = 'tl', my_dep=':d')",
+        "",
+        "dep_rule(name = 'd')");
+
+    getConfiguredTarget("//test/skylark:tl");
+    assertContainsEvent(
+        "My Dep Providers: <target //test/skylark:d, keys:[FooInfo, BarInfo, OutputGroupInfo]>");
+  }
+
+  @Test
   public void testRuleClassImplicitOutputFunctionPrints() throws Exception {
     scratch.file(
         "test/skylark/extension.bzl",