Flatten nested try/catch clauses

This also consistently throws a failed_constructor() when instantiating
SoundFile fails, regardless of the actual exception

libs/ardour/import.cc

@@ -80,9 +80,9 @@ static boost::shared_ptr<ImportableSource>
 open_importable_source (const string& path, samplecnt_t samplerate, ARDOUR::SrcQuality quality)
 {
 	/* try libsndfile first, because it can get BWF info from .wav, which ExtAudioFile cannot.
-	   We don't necessarily need that information in an ImportableSource, but it keeps the
+	 * We don't necessarily need that information in an ImportableSource, but it keeps the
-	   logic the same as in SourceFactory::create()
+	 * logic the same as in SourceFactory::create()
-	*/
+	 */
 
 	try {
 		boost::shared_ptr<SndFileImportableSource> source(new SndFileImportableSource(path));
@@ -92,16 +92,12 @@ open_importable_source (const string& path, samplecnt_t samplerate, ARDOUR::SrcQ
 		}
 
 		/* rewrap as a resampled source */
-
 		return boost::shared_ptr<ImportableSource>(new ResampledImportableSource(source, samplerate, quality));
-	}
+	} catch (...) { }
-
-	catch (...) {
 
+	/* libsndfile failed, see if we can use CoreAudio to handle the IO */
 #ifdef HAVE_COREAUDIO
-
+	try {
-		/* libsndfile failed, see if we can use CoreAudio to handle the IO */
-
 		CAImportableSource* src = new CAImportableSource(path);
 		boost::shared_ptr<CAImportableSource> source (src);
 
@@ -110,14 +106,11 @@ open_importable_source (const string& path, samplecnt_t samplerate, ARDOUR::SrcQ
 		}
 
 		/* rewrap as a resampled source */
-
 		return boost::shared_ptr<ImportableSource>(new ResampledImportableSource(source, samplerate, quality));
-
+	} catch (...) { }
-#else
-		throw; // rethrow
 #endif
 
-	}
+	throw failed_constructor ();
 }
 
 vector<string>

libs/ardour/source_factory.cc

@@ -248,27 +248,23 @@ SourceFactory::createExternal (DataType type, Session& s, const string& path,
 		if (!(flags & Destructive)) {
 
 			try {
-
 				Source* src = new SndFileSource (s, path, chn, flags);
 #ifdef BOOST_SP_ENABLE_DEBUG_HOOKS
 				// boost_debug_shared_ptr_mark_interesting (src, "Source");
 #endif
 				boost::shared_ptr<Source> ret (src);
-
 				if (setup_peakfile (ret, defer_peaks)) {
 					return boost::shared_ptr<Source>();
 				}
-
 				ret->check_for_analysis_data_on_disk ();
 				if (announce) {
 					SourceCreated (ret);
 				}
 				return ret;
-			}
+			} catch (failed_constructor& err) { }
 
-			catch (failed_constructor& err) {
 #ifdef HAVE_COREAUDIO
-
+			try {
 				Source* src = new CoreAudioSource (s, path, chn, flags);
 #ifdef BOOST_SP_ENABLE_DEBUG_HOOKS
 				// boost_debug_shared_ptr_mark_interesting (src, "Source");
@@ -282,16 +278,15 @@ SourceFactory::createExternal (DataType type, Session& s, const string& path,
 					SourceCreated (ret);
 				}
 				return ret;
-
+			} catch (...) { }
-#else
-				throw; // rethrow
 #endif
-			}
 
 		} else {
 			// eh?
 		}
 
+		throw failed_constructor ();
+
 	} else if (type == DataType::MIDI) {
 
 		try {