[#1137] Fix ClassCastException in annotation processor when an option has completionCandidates

Closes #1137

RELEASE-NOTES.md

@@ -22,6 +22,7 @@ Picocli follows [semantic versioning](http://semver.org/).
 * [#1124] Enhancement: automatically generate a better summary in the `AutoComplete.GenerateCompletion` generated man page.
 * [#1126] Enhancement: Make picocli trace levels case-insensitive.
 * [#1128] Enhancement: `ParameterException` caused by `TypeConversionException` now have their cause exception set.
+* [#1137] Bugfix: The `picocli-codegen` annotation processor causes the build to fail with a `ClassCastException` when an option has `completionCandidates` defined.
 * [#1127] DOC: Custom ShortErrorMessageHandler manual example should use bold red for error message.
 * [#1130] DOC: Clarify how to run picocli-based applications.
 * [#1131] DOC: Add anchor links before section titles in user manual.

picocli-annotation-processing-tests/src/main/java/picocli/annotation/processing/tests/CommandSpecYamlPrinter.java

@@ -225,15 +225,8 @@ public class CommandSpecYamlPrinter {
     }
 
     private String iter(Iterable<String> iterable) {
-        if (iterable == null) { return "null"; }
-        StringBuilder sb = new StringBuilder();
-        sb.append("[");
-        String sep = "";
-        for (String str : iterable) {
-            sb.append(sep).append(str);
-            sep = ", ";
-        }
-        return sb.append("]").toString();
+        // cannot list actual completion candidates: class cannot be instantiated at compile time
+        return String.valueOf(iterable);
     }
 
     @Command(name = "CommandSpecYamlPrinter", mixinStandardHelpOptions = true,

picocli-annotation-processing-tests/src/test/java/picocli/annotation/processing/tests/Issue1137Test.java

@@ -0,0 +1,41 @@
+package picocli.annotation.processing.tests;
+
+import com.google.testing.compile.Compilation;
+import com.google.testing.compile.JavaFileObjects;
+import org.junit.Test;
+
+import javax.annotation.processing.Processor;
+import javax.tools.StandardLocation;
+
+import static com.google.testing.compile.CompilationSubject.assertThat;
+import static com.google.testing.compile.Compiler.javac;
+import static picocli.annotation.processing.tests.Resources.slurp;
+import static picocli.annotation.processing.tests.YamlAssert.compareCommandYamlDump;
+
+public class Issue1137Test {
+    @Test
+    public void testIssue1137() {
+        Processor processor = new AnnotatedCommandSourceGeneratorProcessor();
+        Compilation compilation =
+                javac()
+                        .withProcessors(processor)
+                        .compile(JavaFileObjects.forResource(
+                                "picocli/issue1137/Issue1137.java"));
+
+        assertThat(compilation).succeeded();
+    }
+
+    @Test
+    public void testIssue1137Details() {
+
+        Compilation compilation = compareCommandYamlDump(slurp("/picocli/issue1137/Issue1137.yaml"),
+                JavaFileObjects.forResource("picocli/issue1137/Issue1137.java"));
+
+        assertOnlySourceVersionWarning(compilation);
+    }
+
+    private void assertOnlySourceVersionWarning(Compilation compilation) {
+        assertThat(compilation).hadWarningCount(0); // #826 version warnings are now suppressed
+        // assertThat(compilation).hadWarningContaining("Supported source version 'RELEASE_6' from annotation processor 'picocli.annotation.processing.tests");
+    }
+}

picocli-annotation-processing-tests/src/test/resources/picocli/issue1137/Issue1137.java

@@ -0,0 +1,39 @@
+package picocli.issue1137;
+
+import picocli.CommandLine;
+import picocli.CommandLine.Command;
+import picocli.CommandLine.Model.CommandSpec;
+import picocli.CommandLine.Option;
+import picocli.CommandLine.Spec;
+
+import java.util.Arrays;
+import java.util.ArrayList;
+import java.util.UUID;
+import java.util.concurrent.Callable;
+
+@Command(name = "top",
+        version = {"test 1.0"},
+        resourceBundle = "mybundle5")
+public class Issue1137 implements Callable<Integer> {
+
+    @CommandLine.Option(names = "--level",
+            description = "Level.",
+            defaultValue = "OFF",
+            showDefaultValue = CommandLine.Help.Visibility.ALWAYS,
+            completionCandidates = LevelCompletion.class)
+    private String level;
+
+    @Spec
+    CommandSpec spec;
+
+    @Override
+    public Integer call() throws Exception {
+        return 0;
+    }
+
+    public static class LevelCompletion extends ArrayList<String> {
+        public LevelCompletion() {
+            super(Arrays.asList("OFF", "INFO", "WARN"));
+        }
+    }
+}

picocli-annotation-processing-tests/src/test/resources/picocli/issue1137/Issue1137.yaml

@@ -0,0 +1,70 @@
+---
+CommandSpec:
+  name: 'top'
+  aliases: []
+  userObject: picocli.issue1137.Issue1137
+  helpCommand: false
+  defaultValueProvider: null
+  versionProvider: null
+  version: [test 1.0]
+  ArgGroups: []
+  Options:
+  - names: [--level]
+    usageHelp: false
+    versionHelp: false
+    description: [Level.]
+    descriptionKey: ''
+    typeInfo: CompileTimeTypeInfo(java.lang.String, aux=[java.lang.String], collection=false, map=false)
+    arity: 1
+    splitRegex: ''
+    interactive: false
+    required: false
+    hidden: false
+    hideParamSyntax: false
+    defaultValue: 'OFF'
+    showDefaultValue: ALWAYS
+    hasInitialValue: false
+    initialValue: 'null'
+    paramLabel: '<level>'
+    converters: []
+    completionCandidates: CompletionCandidatesMetaData(picocli.issue1137.Issue1137.LevelCompletion)
+    getter: AnnotatedElementHolder(FIELD level in picocli.issue1137.Issue1137)
+    setter: AnnotatedElementHolder(FIELD level in picocli.issue1137.Issue1137)
+  PositionalParams: []
+  UnmatchedArgsBindings: []
+  Mixins: []
+  UsageMessageSpec:
+    width: 80
+    abbreviateSynopsis: false
+    hidden: false
+    showDefaultValues: false
+    sortOptions: true
+    requiredOptionMarker: ' '
+    headerHeading: ''
+    header: []
+    synopsisHeading: 'Usage: '
+    customSynopsis: []
+    descriptionHeading: ''
+    description: []
+    parameterListHeading: ''
+    optionListHeading: ''
+    commandListHeading: 'Commands:%n'
+    footerHeading: ''
+    footer: []
+  ParserSpec:
+    separator: '='
+    endOfOptionsDelimiter: '--'
+    expandAtFiles: true
+    atFileCommentChar: '#'
+    overwrittenOptionsAllowed: false
+    unmatchedArgumentsAllowed: false
+    unmatchedOptionsArePositionalParams: false
+    stopAtUnmatched: false
+    stopAtPositional: false
+    posixClusteredShortOptionsAllowed: true
+    aritySatisfiedByAttachedOptionParam: false
+    caseInsensitiveEnumValuesAllowed: false
+    collectErrors: false
+    limitSplit: false
+    toggleBooleanFlags: false
+  Subcommands: []

picocli-codegen/src/main/java/picocli/codegen/annotation/processing/CompletionCandidatesMetaData.java

@@ -41,7 +41,7 @@ class CompletionCandidatesMetaData implements Iterable<String>, ITypeMetaData {
                 for (ExecutableElement attribute : elementValues.keySet()) {
                     if ("completionCandidates".equals(attribute.getSimpleName().toString())) {
                         AnnotationValue typeMirror = elementValues.get(attribute);
-                        return new CompletionCandidatesMetaData((TypeMirror) typeMirror);
+                        return new CompletionCandidatesMetaData((TypeMirror) typeMirror.getValue());
                     }
                 }
             }
@@ -72,7 +72,7 @@ class CompletionCandidatesMetaData implements Iterable<String>, ITypeMetaData {
     /** Always returns {@code null}. */
     @Override
     public Iterator<String> iterator() {
-        return null;
+        throw new UnsupportedOperationException("Cannot instantiate " + typeMirror + " at compile time.");
     }
 
     /**