Restrict migration to safe-logging to source sets that have the library

changelog/@unreleased/pr-981.v2.yml

@@ -0,0 +1,6 @@
+type: improvement
+improvement:
+  description: Stop migrating source sets to safe-logging, unless they already have
+    the requisite libraries (`com.palantir.safe-logging:{preconditions,safe-logging}`).
+  links:
+  - https://github.com/palantir/gradle-baseline/pull/981

gradle-baseline-java/src/main/groovy/com/palantir/baseline/extensions/BaselineErrorProneExtension.java

@@ -21,7 +21,6 @@
 import org.gradle.api.provider.ListProperty;
 
 public class BaselineErrorProneExtension {
-
     private static final ImmutableList<String> DEFAULT_PATCH_CHECKS = ImmutableList.of(
             // Baseline checks
             "ExecutorSubmitRunnableFutureIgnored",

gradle-baseline-java/src/main/groovy/com/palantir/baseline/plugins/BaselineErrorProne.java

@@ -27,6 +27,7 @@
 import java.util.List;
 import java.util.Map;
 import java.util.Optional;
+import java.util.function.Predicate;
 import java.util.stream.Collectors;
 import java.util.stream.Stream;
 import net.ltgt.gradle.errorprone.CheckSeverity;
@@ -242,6 +243,9 @@ private static Stream<String> getNotDisabledErrorproneChecks(
             BaselineErrorProneExtension errorProneExtension,
             JavaCompile javaCompile,
             ErrorProneOptions errorProneOptions) {
+
+        Predicate<String> filterOutPreconditions = filterOutPreconditions(javaCompile.getClasspath());
+
         return errorProneExtension.getPatchChecks().get().stream().filter(check -> {
             if (checkExplicitlyDisabled(errorProneOptions, check)) {
                 log.info(
@@ -250,10 +254,37 @@ private static Stream<String> getNotDisabledErrorproneChecks(
                         check);
                 return false;
             }
-            return true;
+            return filterOutPreconditions.test(check);
         });
     }
 
+    /** Filters out preconditions checks if the required libraries are not on the classpath. */
+    public static Predicate<String> filterOutPreconditions(FileCollection compileClasspath) {
+        boolean hasSafeLogging = !compileClasspath.filter(file -> file.getName().startsWith("safe-logging-")).isEmpty();
+        boolean hasPreconditions =
+                // The real 'preconditions' brings in 'safe-logging'. Because of inaccurate jar name checks, we
+                // use that fact to ensure we're not picking up another jar named 'preconditions' by mistake.
+                hasSafeLogging
+                        && !compileClasspath.filter(file -> file.getName().startsWith("preconditions-")).isEmpty();
+        return check -> {
+            if (!hasPreconditions && check.equals("PreferSafeLoggingPreconditions")) {
+                log.info(
+                        "Disabling check PreferSafeLoggingPreconditions as 'com.palantir.safe-logging:safe-logging' "
+                                + "missing from source set for {}",
+                        compileClasspath);
+                return false;
+            }
+            if (!hasSafeLogging && check.equals("PreferSafeLoggableExceptions")) {
+                log.info(
+                        "Disabling check PreferSafeLoggableExceptions as 'com.palantir.safe-logging:preconditions' "
+                                + "missing from source set for {}",
+                        compileClasspath);
+                return false;
+            }
+            return true;
+        };
+    }
+
     private static boolean isRefactoring(Project project) {
         return isRefasterRefactoring(project) || isErrorProneRefactoring(project);
     }