Make KDoc generate documentation on red code

KDoc is not a compiler, so it should not care whether or not the code is valid.
Therefore suppress the compiler's exit code, errors and warnings in KDoc plugin

libraries/tools/kdoc-maven-plugin/src/main/java/org/jetbrains/kotlin/maven/doc/KDocMojo.java

@@ -17,8 +17,11 @@
 package org.jetbrains.kotlin.maven.doc;
 
 import org.apache.maven.plugin.MojoExecutionException;
+import org.jetbrains.jet.cli.common.CLICompiler;
+import org.jetbrains.jet.cli.common.ExitCode;
 import org.jetbrains.jet.cli.common.arguments.CommonCompilerArguments;
 import org.jetbrains.jet.cli.common.arguments.K2JVMCompilerArguments;
+import org.jetbrains.jet.cli.common.messages.MessageCollector;
 import org.jetbrains.jet.cli.jvm.K2JVMCompiler;
 import org.jetbrains.kotlin.doc.KDocArguments;
 import org.jetbrains.kotlin.doc.KDocCompiler;
@@ -183,6 +186,21 @@ public class KDocMojo extends KotlinCompileMojoBase {
         return new KDocArguments();
     }
 
+    @Override
+    protected ExitCode executeCompiler(
+            CLICompiler compiler,
+            CommonCompilerArguments arguments,
+            MessageCollector messageCollector
+    ) {
+        ExitCode exitCode = super.executeCompiler(compiler, arguments, messageCollector);
+        if (exitCode == ExitCode.COMPILATION_ERROR) {
+            // KDoc should ignore compilation errors, since it's not supposed to compile code.
+            // KDoc is supposed to generate documentation by the code that may be correct or not
+            return ExitCode.OK;
+        }
+        return exitCode;
+    }
+
     @Override
     protected void configureCompilerArguments(CommonCompilerArguments arguments) throws MojoExecutionException {
         if (arguments instanceof K2JVMCompilerArguments) {