Add warning for long chain of recursive --configs.

Configs are recursive, but let's be reasonable. If there's an absurdly long list of configs inheritance, warn about it. It is probably unnecessary, and might very well be unintentional and surprising to the user.

RELNOTES: None.
PiperOrigin-RevId: 176405183

1 files changed, 147 insertions, 0 deletions

diff --git a/src/test/java/com/google/devtools/build/lib/runtime/BlazeOptionHandlerTest.java b/src/test/java/com/google/devtools/build/lib/runtime/BlazeOptionHandlerTest.java
index 3a0acb31b8..1b52ee1895 100644
--- a/src/test/java/com/google/devtools/build/lib/runtime/BlazeOptionHandlerTest.java
+++ b/src/test/java/com/google/devtools/build/lib/runtime/BlazeOptionHandlerTest.java
@@ -1272,6 +1272,153 @@ public class BlazeOptionHandlerTest {
         .inOrder();
   }
 
+  private static final ImmutableList<String> GREEK_ALPHABET_CHAIN =
+      ImmutableList.of(
+          "--default_override=0:c0:alpha=--test_multiple_string=alpha",
+          "--default_override=0:c0:alpha=--config=beta",
+          "--default_override=0:c0:beta=--test_multiple_string=beta",
+          "--default_override=0:c0:beta=--config=gamma",
+          "--default_override=0:c0:gamma=--test_multiple_string=gamma",
+          "--default_override=0:c0:gamma=--config=delta",
+          "--default_override=0:c0:delta=--test_multiple_string=delta",
+          "--default_override=0:c0:delta=--config=epsilon",
+          "--default_override=0:c0:epsilon=--test_multiple_string=epsilon",
+          "--default_override=0:c0:epsilon=--config=zeta",
+          "--default_override=0:c0:zeta=--test_multiple_string=zeta",
+          "--default_override=0:c0:zeta=--config=eta",
+          "--default_override=0:c0:eta=--test_multiple_string=eta",
+          "--default_override=0:c0:eta=--config=theta",
+          "--default_override=0:c0:theta=--test_multiple_string=theta",
+          "--default_override=0:c0:theta=--config=iota",
+          "--default_override=0:c0:iota=--test_multiple_string=iota",
+          "--default_override=0:c0:iota=--config=kappa",
+          "--default_override=0:c0:kappa=--test_multiple_string=kappa",
+          "--default_override=0:c0:kappa=--config=lambda",
+          "--default_override=0:c0:lambda=--test_multiple_string=lambda",
+          "--default_override=0:c0:lambda=--config=mu",
+          "--default_override=0:c0:mu=--test_multiple_string=mu");
+
+  private void testParseOptions_longChainOfConfigs_12long() {
+    ImmutableList<String> args =
+        ImmutableList.<String>builder()
+            .add("c0")
+            .addAll(GREEK_ALPHABET_CHAIN)
+            .add("--rc_source=/somewhere/.blazerc")
+            .add("--config=alpha")
+            .build();
+
+    optionHandler.parseOptions(args, eventHandler);
+    assertThat(parser.getResidue()).isEmpty();
+    assertThat(optionHandler.getRcfileNotes())
+        .containsExactly(
+            "Found applicable config definition c0:alpha in file /somewhere/.blazerc: "
+                + "--test_multiple_string=alpha --config=beta",
+            "Found applicable config definition c0:beta in file /somewhere/.blazerc: "
+                + "--test_multiple_string=beta --config=gamma",
+            "Found applicable config definition c0:gamma in file /somewhere/.blazerc: "
+                + "--test_multiple_string=gamma --config=delta",
+            "Found applicable config definition c0:delta in file /somewhere/.blazerc: "
+                + "--test_multiple_string=delta --config=epsilon",
+            "Found applicable config definition c0:epsilon in file /somewhere/.blazerc: "
+                + "--test_multiple_string=epsilon --config=zeta",
+            "Found applicable config definition c0:zeta in file /somewhere/.blazerc: "
+                + "--test_multiple_string=zeta --config=eta",
+            "Found applicable config definition c0:eta in file /somewhere/.blazerc: "
+                + "--test_multiple_string=eta --config=theta",
+            "Found applicable config definition c0:theta in file /somewhere/.blazerc: "
+                + "--test_multiple_string=theta --config=iota",
+            "Found applicable config definition c0:iota in file /somewhere/.blazerc: "
+                + "--test_multiple_string=iota --config=kappa",
+            "Found applicable config definition c0:kappa in file /somewhere/.blazerc: "
+                + "--test_multiple_string=kappa --config=lambda",
+            "Found applicable config definition c0:lambda in file /somewhere/.blazerc: "
+                + "--test_multiple_string=lambda --config=mu",
+            "Found applicable config definition c0:mu in file /somewhere/.blazerc: "
+                + "--test_multiple_string=mu");
+    TestOptions options = parser.getOptions(TestOptions.class);
+    assertThat(options).isNotNull();
+    assertThat(options.testMultipleString)
+        .containsExactly(
+            "alpha", "beta", "gamma", "delta", "epsilon", "zeta", "eta", "theta", "iota", "kappa",
+            "lambda", "mu")
+        .inOrder();
+  }
+
+  @Test
+  public void testParseOptions_longChain_FixedPoint() {
+    makeFixedPointExpandingConfigOptionHandler();
+    testParseOptions_longChainOfConfigs_12long();
+    assertThat(eventHandler.getEvents()).isEmpty();
+  }
+
+  @Test
+  public void testParseOptions_longChain_inPlace() {
+    makeInPlaceExpandingConfigOptionHandler();
+    testParseOptions_longChainOfConfigs_12long();
+    // Expect only one warning, we don't want multiple warnings for the same chain.
+    assertThat(eventHandler.getEvents())
+        .containsExactly(
+            Event.warn(
+                "There is a recursive chain of configs 12 configs long: [alpha, beta, gamma, "
+                    + "delta, epsilon, zeta, eta, theta, iota, kappa, lambda, mu]. This seems "
+                    + "excessive, and might be hiding errors."));
+  }
+
+  private void testParseOptions_twoLongChains() {
+    ImmutableList<String> args =
+        ImmutableList.<String>builder()
+            .add("c0")
+            .addAll(GREEK_ALPHABET_CHAIN)
+            .add("--rc_source=/somewhere/.blazerc")
+            .add("--config=alpha")
+            .add("--config=gamma")
+            .build();
+
+    optionHandler.parseOptions(args, eventHandler);
+    assertThat(parser.getResidue()).isEmpty();
+  }
+
+  @Test
+  public void testParseOptions_2LongChains_FixedPoint() {
+    makeFixedPointExpandingConfigOptionHandler();
+    testParseOptions_twoLongChains();
+    // In fixed point, the repetition --config=gamma does not led to a new expansion, but it does
+    // mean that gamma gets expanded in the first round, so the ordering is weird.
+    TestOptions options = parser.getOptions(TestOptions.class);
+    assertThat(options).isNotNull();
+    assertThat(options.testMultipleString)
+        .containsExactly(
+            "alpha", "gamma", "beta", "delta", "epsilon", "zeta", "eta", "theta", "iota", "kappa",
+            "lambda", "mu")
+        .inOrder();
+    assertThat(eventHandler.getEvents()).isEmpty();
+  }
+
+  @Test
+  public void testParseOptions_2LongChains_inPlace() {
+    makeInPlaceExpandingConfigOptionHandler();
+    testParseOptions_twoLongChains();
+    // Expect the second --config=gamma to have started a second chain, and get warnings about both.
+    TestOptions options = parser.getOptions(TestOptions.class);
+    assertThat(options).isNotNull();
+    assertThat(options.testMultipleString)
+        .containsExactly(
+            "alpha", "beta", "gamma", "delta", "epsilon", "zeta", "eta", "theta", "iota", "kappa",
+            "lambda", "mu", "gamma", "delta", "epsilon", "zeta", "eta", "theta", "iota", "kappa",
+            "lambda", "mu")
+        .inOrder();
+    assertThat(eventHandler.getEvents())
+        .containsExactly(
+            Event.warn(
+                "There is a recursive chain of configs 12 configs long: [alpha, beta, gamma, "
+                    + "delta, epsilon, zeta, eta, theta, iota, kappa, lambda, mu]. This seems "
+                    + "excessive, and might be hiding errors."),
+            Event.warn(
+                "There is a recursive chain of configs 10 configs long: [gamma, delta, epsilon, "
+                    + "zeta, eta, theta, iota, kappa, lambda, mu]. This seems excessive, "
+                    + "and might be hiding errors."));
+  }
+
   private void testWarningFlag() {
     optionHandler.parseOptions(
         ImmutableList.of(