userdiff: improve java hunk header regex

Currently, the git diff hunk headers show the wrong method signature if the
method has a qualified return type, an array return type, or a generic return
type because the regex doesn't allow dots (.), [], or < and > in the return
type.  Also, type parameter declarations couldn't be matched.

Add several t4018 tests asserting the right hunk headers for different cases:

  - enum constant change
  - change in generic method with bounded type parameters
  - change in generic method with wildcard
  - field change in a nested class

Signed-off-by: Tassilo Horn <tsdh@gnu.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

5 files changed, 34 insertions, 0 deletions

diff --git a/t/t4018/java-class-member-function b/t/t4018/java-class-member-function
index 298bc7a71b..3b95f68b3b 100644
--- a/t/t4018/java-class-member-function
+++ b/t/t4018/java-class-member-function
@@ -3,6 +3,10 @@ public class Beer
 	int special;
 	public static void main(String RIGHT[])
 	{
+		someMethodCall();
+		someOtherMethod("17")
+			.doThat();
+		// Whatever
 		System.out.print("ChangeMe");
 	}
 }
diff --git a/t/t4018/java-enum-constant b/t/t4018/java-enum-constant
new file mode 100644
index 0000000000..a1931c8379
--- /dev/null
+++ b/t/t4018/java-enum-constant
@@ -0,0 +1,6 @@
+private enum RIGHT {
+    ONE,
+    TWO,
+    THREE,
+    ChangeMe
+}
diff --git a/t/t4018/java-method-return-generic-bounded b/t/t4018/java-method-return-generic-bounded
new file mode 100644
index 0000000000..66dd78c379
--- /dev/null
+++ b/t/t4018/java-method-return-generic-bounded
@@ -0,0 +1,9 @@
+class MyExample {
+    public <T extends Bar & Foo<T>, R> Map<T, R[]> foo(String[] RIGHT) {
+        someMethodCall();
+        someOtherMethod()
+            .doThat();
+        // Whatever...
+        return (List<T>) Arrays.asList("ChangeMe");
+    }
+}
diff --git a/t/t4018/java-method-return-generic-wildcard b/t/t4018/java-method-return-generic-wildcard
new file mode 100644
index 0000000000..96e9e5f2c1
--- /dev/null
+++ b/t/t4018/java-method-return-generic-wildcard
@@ -0,0 +1,9 @@
+class MyExample {
+    public List<? extends Comparable> foo(String[] RIGHT) {
+        someMethodCall();
+        someOtherMethod()
+            .doThat();
+        // Whatever...
+        return Arrays.asList("ChangeMe");
+    }
+}
diff --git a/t/t4018/java-nested-field b/t/t4018/java-nested-field
new file mode 100644
index 0000000000..d92d3ec688
--- /dev/null
+++ b/t/t4018/java-nested-field
@@ -0,0 +1,6 @@
+class MyExample {
+    private static class RIGHT {
+        // change an inner class field
+        String inner = "ChangeMe";
+    }
+}