ErrorProne: Enable and fix UnusedException check

Enable UnusedException at ERROR level which causes the build to fail
in many places with:

  [UnusedException] This catch block catches an symbol and re-throws
  another, but swallows the caught symbol rather than setting it as a
  cause. This can make debugging harder.

Fix it by setting the caught exception as cause on the subsequently
thrown exception.

Note: The grammatically incorrect error message is copy-pasted as-is
from the version of ErrorProne currently used in Bazel; it has been
fixed by [1] in the latest version.

[1] https://github.com/google/error-prone/commit/d57a39c

Change-Id: I11ed38243091fc12f64f1b2db404ba3f1d2e98b5
Signed-off-by: David Pursehouse <david.pursehouse@gmail.com>
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>

10 files changed, 21 insertions, 11 deletions

diff --git a/org.eclipse.jgit.pgm/src/org/eclipse/jgit/pgm/Checkout.java b/org.eclipse.jgit.pgm/src/org/eclipse/jgit/pgm/Checkout.java
index 455abcd37c..98724bfceb 100644
--- a/org.eclipse.jgit.pgm/src/org/eclipse/jgit/pgm/Checkout.java
+++ b/org.eclipse.jgit.pgm/src/org/eclipse/jgit/pgm/Checkout.java
@@ -100,7 +100,7 @@ class Checkout extends TextBuiltin {
 						.format(CLIText.get().pathspecDidNotMatch, name), e);
 			} catch (RefAlreadyExistsException e) {
 				throw die(MessageFormat
-						.format(CLIText.get().branchAlreadyExists, name));
+						.format(CLIText.get().branchAlreadyExists, name), e);
 			} catch (CheckoutConflictException e) {
 				StringBuilder builder = new StringBuilder();
 				builder.append(CLIText.get().checkoutConflict);
diff --git a/org.eclipse.jgit.pgm/src/org/eclipse/jgit/pgm/Clone.java b/org.eclipse.jgit.pgm/src/org/eclipse/jgit/pgm/Clone.java
index 243e99fdf2..8f80d6d70e 100644
--- a/org.eclipse.jgit.pgm/src/org/eclipse/jgit/pgm/Clone.java
+++ b/org.eclipse.jgit.pgm/src/org/eclipse/jgit/pgm/Clone.java
@@ -110,7 +110,7 @@ class Clone extends AbstractFetchCommand implements CloneCommand.Callback {
 				outw.println(CLIText.get().clonedEmptyRepository);
 		} catch (InvalidRemoteException e) {
 			throw die(MessageFormat.format(CLIText.get().doesNotExist,
-					sourceUri));
+					sourceUri), e);
 		} finally {
 			if (db != null)
 				db.close();
diff --git a/org.eclipse.jgit.pgm/src/org/eclipse/jgit/pgm/ReceivePack.java b/org.eclipse.jgit.pgm/src/org/eclipse/jgit/pgm/ReceivePack.java
index cbb5d846ba..f570f7f99b 100644
--- a/org.eclipse.jgit.pgm/src/org/eclipse/jgit/pgm/ReceivePack.java
+++ b/org.eclipse.jgit.pgm/src/org/eclipse/jgit/pgm/ReceivePack.java
@@ -42,7 +42,7 @@ class ReceivePack extends TextBuiltin {
 			db = key.open(true /* must exist */);
 		} catch (RepositoryNotFoundException notFound) {
 			throw die(MessageFormat.format(CLIText.get().notAGitRepository,
-					dstGitdir.getPath()));
+					dstGitdir.getPath()), notFound);
 		} catch (IOException e) {
 			throw die(e.getMessage(), e);
 		}
diff --git a/org.eclipse.jgit.pgm/src/org/eclipse/jgit/pgm/Tag.java b/org.eclipse.jgit.pgm/src/org/eclipse/jgit/pgm/Tag.java
index 8c39886031..b408b78f3c 100644
--- a/org.eclipse.jgit.pgm/src/org/eclipse/jgit/pgm/Tag.java
+++ b/org.eclipse.jgit.pgm/src/org/eclipse/jgit/pgm/Tag.java
@@ -74,7 +74,7 @@ class Tag extends TextBuiltin {
 						command.call();
 					} catch (RefAlreadyExistsException e) {
 						throw die(MessageFormat.format(
-								CLIText.get().tagAlreadyExists, tagName));
+								CLIText.get().tagAlreadyExists, tagName), e);
 					}
 				}
 			} else {
diff --git a/org.eclipse.jgit.pgm/src/org/eclipse/jgit/pgm/UploadPack.java b/org.eclipse.jgit.pgm/src/org/eclipse/jgit/pgm/UploadPack.java
index 69c8eb5701..36103f2e6f 100644
--- a/org.eclipse.jgit.pgm/src/org/eclipse/jgit/pgm/UploadPack.java
+++ b/org.eclipse.jgit.pgm/src/org/eclipse/jgit/pgm/UploadPack.java
@@ -50,7 +50,7 @@ class UploadPack extends TextBuiltin {
 			up.upload(ins, outs, errs);
 		} catch (RepositoryNotFoundException notFound) {
 			throw die(MessageFormat.format(CLIText.get().notAGitRepository,
-					srcGitdir.getPath()));
+					srcGitdir.getPath()), notFound);
 		} catch (IOException e) {
 			throw die(e.getMessage(), e);
 		}
diff --git a/org.eclipse.jgit.pgm/src/org/eclipse/jgit/pgm/debug/RebuildCommitGraph.java b/org.eclipse.jgit.pgm/src/org/eclipse/jgit/pgm/debug/RebuildCommitGraph.java
index ddd48da466..8d884c12db 100644
--- a/org.eclipse.jgit.pgm/src/org/eclipse/jgit/pgm/debug/RebuildCommitGraph.java
+++ b/org.eclipse.jgit.pgm/src/org/eclipse/jgit/pgm/debug/RebuildCommitGraph.java
@@ -235,7 +235,9 @@ class RebuildCommitGraph extends TextBuiltin {
 				try {
 					lck.write(content);
 				} catch (IOException ioe) {
-					throw new ObjectWritingException(MessageFormat.format(CLIText.get().cantWrite, file));
+					throw new ObjectWritingException(
+							MessageFormat.format(CLIText.get().cantWrite, file),
+							ioe);
 				}
 				if (!lck.commit())
 					throw new ObjectWritingException(MessageFormat.format(CLIText.get().cantWrite, file));
@@ -266,7 +268,9 @@ class RebuildCommitGraph extends TextBuiltin {
 						errw.println(MessageFormat.format(CLIText.get().skippingObject, type, name));
 						continue;
 					}
-					throw new MissingObjectException(id, type);
+					MissingObjectException mue1 = new MissingObjectException(id, type);
+					mue1.initCause(mue);
+					throw mue1;
 				}
 				refs.put(name, new ObjectIdRef.Unpeeled(Ref.Storage.PACKED,
 						name, id));
diff --git a/org.eclipse.jgit.pgm/src/org/eclipse/jgit/pgm/debug/ShowPackDelta.java b/org.eclipse.jgit.pgm/src/org/eclipse/jgit/pgm/debug/ShowPackDelta.java
index 6f0aba377e..49f7ada457 100644
--- a/org.eclipse.jgit.pgm/src/org/eclipse/jgit/pgm/debug/ShowPackDelta.java
+++ b/org.eclipse.jgit.pgm/src/org/eclipse/jgit/pgm/debug/ShowPackDelta.java
@@ -57,7 +57,7 @@ class ShowPackDelta extends TextBuiltin {
 			if (BinaryDelta.getResultSize(delta) != size)
 				throw die("Object " + obj.name() + " is not a delta"); //$NON-NLS-1$ //$NON-NLS-2$
 		} catch (ArrayIndexOutOfBoundsException bad) {
-			throw die("Object " + obj.name() + " is not a delta"); //$NON-NLS-1$ //$NON-NLS-2$
+			throw die("Object " + obj.name() + " is not a delta", bad); //$NON-NLS-1$ //$NON-NLS-2$
 		}
 
 		outw.println(BinaryDelta.format(delta));
diff --git a/org.eclipse.jgit.pgm/src/org/eclipse/jgit/pgm/opt/AbstractTreeIteratorHandler.java b/org.eclipse.jgit.pgm/src/org/eclipse/jgit/pgm/opt/AbstractTreeIteratorHandler.java
index 07a1bb801f..d8604726ab 100644
--- a/org.eclipse.jgit.pgm/src/org/eclipse/jgit/pgm/opt/AbstractTreeIteratorHandler.java
+++ b/org.eclipse.jgit.pgm/src/org/eclipse/jgit/pgm/opt/AbstractTreeIteratorHandler.java
@@ -101,8 +101,10 @@ public class AbstractTreeIteratorHandler extends
 		try (ObjectReader curs = clp.getRepository().newObjectReader()) {
 			p.reset(curs, clp.getRevWalk().parseTree(id));
 		} catch (MissingObjectException | IncorrectObjectTypeException e) {
-			throw new CmdLineException(clp,
+			CmdLineException cle = new CmdLineException(clp,
 					CLIText.format(CLIText.get().notATree), name);
+			cle.initCause(e);
+			throw cle;
 		} catch (IOException e) {
 			throw new CmdLineException(clp,
 					CLIText.format(CLIText.get().cannotReadBecause), name,
diff --git a/org.eclipse.jgit.pgm/src/org/eclipse/jgit/pgm/opt/RevCommitHandler.java b/org.eclipse.jgit.pgm/src/org/eclipse/jgit/pgm/opt/RevCommitHandler.java
index f521775c7c..8b2bed36a7 100644
--- a/org.eclipse.jgit.pgm/src/org/eclipse/jgit/pgm/opt/RevCommitHandler.java
+++ b/org.eclipse.jgit.pgm/src/org/eclipse/jgit/pgm/opt/RevCommitHandler.java
@@ -98,8 +98,10 @@ public class RevCommitHandler extends OptionHandler<RevCommit> {
 		try {
 			c = clp.getRevWalk().parseCommit(id);
 		} catch (MissingObjectException | IncorrectObjectTypeException e) {
-			throw new CmdLineException(clp,
+			CmdLineException cle = new CmdLineException(clp,
 					CLIText.format(CLIText.get().notACommit), name);
+			cle.initCause(e);
+			throw cle;
 		} catch (IOException e) {
 			throw new CmdLineException(clp,
 					CLIText.format(CLIText.get().cannotReadBecause), name,
diff --git a/org.eclipse.jgit.pgm/src/org/eclipse/jgit/pgm/opt/RevTreeHandler.java b/org.eclipse.jgit.pgm/src/org/eclipse/jgit/pgm/opt/RevTreeHandler.java
index fa96361681..357886d0fa 100644
--- a/org.eclipse.jgit.pgm/src/org/eclipse/jgit/pgm/opt/RevTreeHandler.java
+++ b/org.eclipse.jgit.pgm/src/org/eclipse/jgit/pgm/opt/RevTreeHandler.java
@@ -70,8 +70,10 @@ public class RevTreeHandler extends OptionHandler<RevTree> {
 		try {
 			c = clp.getRevWalk().parseTree(id);
 		} catch (MissingObjectException | IncorrectObjectTypeException e) {
-			throw new CmdLineException(clp,
+			CmdLineException cle = new CmdLineException(clp,
 					CLIText.format(CLIText.get().notATree), name);
+			cle.initCause(e);
+			throw cle;
 		} catch (IOException e) {
 			throw new CmdLineException(clp,
 					CLIText.format(CLIText.get().cannotReadBecause), name,