[GR-43070] Track warnings in Native Image build and list them (again) at the very end.

substratevm/src/com.oracle.svm.core/src/com/oracle/svm/core/SubstrateOptions.java

@@ -1711,4 +1711,19 @@ private static void validateEnableFallbackCompilation(HostedOptionKey<Boolean> o
     public static boolean canEnableFallbackCompilation() {
         return !EnableFallbackCompilation.getValue() && !useEconomyCompilerConfig();
     }
+
+    @Option(help = "Passes the numbers of warnings that occurred in the driver phase to the builder.", type = OptionType.Debug, stability = OptionStability.STABLE) //
+    public static final HostedOptionKey<Integer> DriverWarningsCount = new HostedOptionKey<>(0);
+
+    @APIOption(name = "-Werror", defaultValue = "all")//
+    @Option(help = "Treat warnings as errors and terminate build.")//
+    public static final HostedOptionKey<AccumulatingLocatableMultiOptionValue.Strings> TreatWarningsAsError = new HostedOptionKey<>(AccumulatingLocatableMultiOptionValue.Strings.build(), key -> {
+        key.getValue().getValuesWithOrigins().forEach(option -> {
+            if (!option.origin().commandLineLike()) {
+                throw UserError.abort("Option '%s' provided by %s can only be used on the command line.",
+                                SubstrateOptionsParser.commandArgument(key, option.value()), option.origin());
+            }
+        });
+    });
+
 }

substratevm/src/com.oracle.svm.driver/src/com/oracle/svm/driver/NativeImage.java

@@ -1492,6 +1492,8 @@ private int completeImageBuild() {
         // allow native access for all modules on the image builder module path
         var enableNativeAccessModules = getModulesFromPath(imageBuilderModulePath).keySet();
         imageBuilderJavaArgs.add("--enable-native-access=" + String.join(",", enableNativeAccessModules));
+        // pass the number of warnings to the builder process
+        imageBuilderArgs.add(oH(SubstrateOptions.DriverWarningsCount) + LogUtils.getWarningsCount());
 
         boolean useColorfulOutput = configureBuildOutput();
 

substratevm/src/com.oracle.svm.hosted/src/com/oracle/svm/hosted/ProgressReporter.java

@@ -54,6 +54,8 @@
 import java.util.stream.Stream;
 
 import com.oracle.svm.core.RuntimeAssertionsSupport;
+import com.oracle.svm.core.util.UserError;
+import com.oracle.svm.util.LogUtils;
 import org.graalvm.nativeimage.ImageSingletons;
 import org.graalvm.nativeimage.hosted.Feature;
 import org.graalvm.nativeimage.impl.ImageSingletonsSupport;
@@ -795,7 +797,9 @@ public void printEpilog(Optional<String> optionalImageName, Optional<NativeImage
         l().a(outcomePrefix(buildOutcome)).a(" generating '").bold().a(imageName).reset().a("' ")
                         .a(buildOutcome.successful() ? "in" : "after").a(" ").a(timeStats).a(".").println();
 
+        printWarningsCount();
         printErrorMessage(optionalUnhandledThrowable, parsedHostedOptions);
+        checkTreatWarningsAsError();
     }
 
     private static String outcomePrefix(NativeImageGeneratorRunner.BuildOutcome buildOutcome) {
@@ -806,6 +810,46 @@ private static String outcomePrefix(NativeImageGeneratorRunner.BuildOutcome buil
         };
     }
 
+    private void printWarningsCount() {
+        int warningsCount = LogUtils.getWarningsCount() + SubstrateOptions.DriverWarningsCount.getValue();
+        if (warningsCount == 0) {
+            return;
+        }
+
+        l().println();
+        l().yellowBold().a("The build process encountered ").a(warningsCount).a(warningsCount == 1 ? " warning." : " warnings.").reset().println();
+        l().println();
+    }
+
+    private void checkTreatWarningsAsError() {
+        if (SubstrateOptions.TreatWarningsAsError.getValue().contains("all")) {
+            deleteBuiltArtifacts();
+            throw UserError.abort("Build failed: Warnings are treated as errors because the -Werror flag is set.");
+        }
+    }
+
+    /**
+     * Delete built artifacts. This is done e.g. in the -Werror case to ensure we don't "fail on
+     * error" but still have built - but potentially broken - artifacts created.
+     */
+    private void deleteBuiltArtifacts() {
+        BuildArtifacts.singleton().forEach((artifactType, paths) -> {
+            if (artifactType != ArtifactType.BUILD_INFO) {
+                for (Path path : paths) {
+                    try {
+                        if (path.startsWith(SubstrateOptions.getImagePath())) {
+                            java.nio.file.Files.delete(path);
+                        } else {
+                            LogUtils.warning("Cleaning up due to -Werror failed: Cannot delete artifacts not in " + SubstrateOptions.getImagePath() + ". Invalid: " + path);
+                        }
+                    } catch (IOException ex) {
+                        LogUtils.warning("Cleaning up due to -Werror failed: cannot delete " + path + ": " + ex.getMessage());
+                    }
+                }
+            }
+        });
+    }
+
     private void printErrorMessage(Optional<Throwable> optionalUnhandledThrowable, OptionValues parsedHostedOptions) {
         if (optionalUnhandledThrowable.isEmpty()) {
             return;

substratevm/src/com.oracle.svm.util/src/com/oracle/svm/util/LogUtils.java

@@ -29,6 +29,12 @@
 
 // Checkstyle: Allow raw info or warning printing - begin
 public class LogUtils {
+    /**
+     * Number of warnings seen during image build. Note this is limited to the current process, i.e.
+     * there is a split between Driver and Builder.
+     */
+    private static int warningsCount = 0;
+
     /**
      * Print an info message.
      */
@@ -66,6 +72,7 @@ public static void prefixInfo(String prefix, String format, Object... args) {
      */
     public static void warning(String message) {
         System.out.println("Warning: " + message);
+        warningsCount++;
     }
 
     /**
@@ -87,4 +94,8 @@ public static void warning(String format, Object... args) {
     public static void warningDeprecatedEnvironmentVariable(String environmentVariableName) {
         warning("The " + environmentVariableName + " environment variable is deprecated and might be removed in a future release. Please refer to the GraalVM release notes.");
     }
+
+    public static int getWarningsCount() {
+        return warningsCount;
+    }
 }