Only log message about source generators once

Author: keynmol

semanticdb-javac/src/main/java/com/sourcegraph/semanticdb_javac/SemanticdbJavacOptions.java

@@ -123,6 +123,6 @@ private static TargetPaths getJavacClassesDir(SemanticdbJavacOptions result, Con
               JAVAC_CLASSES_DIR_ARG, out.toString());
       result.errors.add(errorMsg);
     }
-    return (new TargetPaths(classOutputDir, sourceOutputDir));
+    return new TargetPaths(classOutputDir, sourceOutputDir);
   }
 }

semanticdb-javac/src/main/java/com/sourcegraph/semanticdb_javac/SemanticdbReporter.java

@@ -31,6 +31,10 @@ public void exception(Throwable e, Tree tree, CompilationUnitTree root) {
     trees.printMessage(Diagnostic.Kind.ERROR, baos.toString(), tree, root);
   }
 
+  public void exception(Throwable e, TaskEvent task) {
+    this.exception(e, task.getCompilationUnit(), task.getCompilationUnit());
+  }
+
   public void info(String message, TaskEvent e) {
     trees.printMessage(
         Diagnostic.Kind.NOTE,

semanticdb-javac/src/main/java/com/sourcegraph/semanticdb_javac/SemanticdbTaskListener.java

@@ -25,6 +25,7 @@ public final class SemanticdbTaskListener implements TaskListener {
   private final SemanticdbReporter reporter;
   private final JavacTypes javacTypes;
   private final Trees trees;
+  private boolean sourceGeneratorsMessageIsLogged = false;
 
   public SemanticdbTaskListener(
       SemanticdbJavacOptions options,
@@ -194,17 +195,19 @@ private Result<Path, String> semanticdbOutputPath(SemanticdbJavacOptions options
       if (options.uriScheme == UriScheme.BAZEL && options.generatedTargetRoot != null) {
         try {
           if (absolutePath.toRealPath().startsWith(options.generatedTargetRoot)) {
-            reporter.info(
-                String.format(
-                    "Path '%s' belongs to the root for generated source files, "
-                        + "as reported by javac ('%s'), therefore a SemanticDB file for it won't be generated",
-                    absolutePath, options.generatedTargetRoot),
-                e);
+            if (!sourceGeneratorsMessageIsLogged) {
+              sourceGeneratorsMessageIsLogged = true;
+              reporter.info(
+                  "Usage of source generators detected - scip-java does not produce SemanticDB files for generated files.\n"
+                      + "This message is logged only once",
+                  e);
+            }
 
             return null;
           }
-        } catch (IOException ioe) {
-          // TODO:
+        } catch (IOException exc) {
+          reporter.exception(exc, e);
+          return null;
         }
       }