[PATCH v4] userdiff: improve java hunk header regex

[Tassilo Horn <tsdh@gnu.org>]

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 increasingly
complex method signatures:

  public String[] myMethod(String[] RIGHT)
  public List<String> myMethod(String[] RIGHT)
  public <T> List<T> myMethod(T[] RIGHT)
  public <AType, B> Map<AType, B> myMethod(String[] RIGHT)
  public <AType, B> java.util.Map<AType, Map<B, B[]>> myMethod(String[] RIGHT)
  public List<? extends Comparable> myMethod(String[] RIGHT)
  public <T extends Serializable & Comparable<T>> List<T> myMethod(String[] RIGHT)

Signed-off-by: Tassilo Horn <tsdh@gnu.org>
---
 t/t4018/java-constructor             |  6 ++++++
 t/t4018/java-enum-constant           |  6 ++++++
 t/t4018/java-nested-field            |  6 ++++++
 t/t4018/java-return-array            |  6 ++++++
 t/t4018/java-return-generic          |  6 ++++++
 t/t4018/java-return-generic-bounded  |  6 ++++++
 t/t4018/java-return-generic-wildcart |  6 ++++++
 t/t4018/java-return-generic2         |  6 ++++++
 t/t4018/java-return-generic3         |  6 ++++++
 t/t4018/java-return-generic4         |  6 ++++++
 userdiff.c                           | 23 ++++++++++++++++++++++-
 11 files changed, 82 insertions(+), 1 deletion(-)
 create mode 100644 t/t4018/java-constructor
 create mode 100644 t/t4018/java-enum-constant
 create mode 100644 t/t4018/java-nested-field
 create mode 100644 t/t4018/java-return-array
 create mode 100644 t/t4018/java-return-generic
 create mode 100644 t/t4018/java-return-generic-bounded
 create mode 100644 t/t4018/java-return-generic-wildcart
 create mode 100644 t/t4018/java-return-generic2
 create mode 100644 t/t4018/java-return-generic3
 create mode 100644 t/t4018/java-return-generic4

diff --git a/t/t4018/java-constructor b/t/t4018/java-constructor
new file mode 100644
index 0000000000..9daf7c5430
--- /dev/null
+++ b/t/t4018/java-constructor
@@ -0,0 +1,6 @@
+public class MyClass {
+    MyClass(String RIGHT) {
+        // Whatever
+        // 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-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";
+    }
+}
diff --git a/t/t4018/java-return-array b/t/t4018/java-return-array
new file mode 100644
index 0000000000..747638b9a8
--- /dev/null
+++ b/t/t4018/java-return-array
@@ -0,0 +1,6 @@
+class MyExample {
+    public String[] myMethod(String[] RIGHT) {
+        // Whatever...
+        return new; // ChangeMe
+    }
+}
diff --git a/t/t4018/java-return-generic b/t/t4018/java-return-generic
new file mode 100644
index 0000000000..161dd8338f
--- /dev/null
+++ b/t/t4018/java-return-generic
@@ -0,0 +1,6 @@
+class MyExample {
+    public List<String> myMethod(String[] RIGHT) {
+        // Whatever...
+        return Arrays.asList("ChangeMe");
+    }
+}
diff --git a/t/t4018/java-return-generic-bounded b/t/t4018/java-return-generic-bounded
new file mode 100644
index 0000000000..440115a788
--- /dev/null
+++ b/t/t4018/java-return-generic-bounded
@@ -0,0 +1,6 @@
+class MyExample {
+    public <T extends Serializable & Comparable<T>> List<T> myMethod(String[] RIGHT) {
+        // Whatever...
+        return (List<T>) Arrays.asList("ChangeMe");
+    }
+}
diff --git a/t/t4018/java-return-generic-wildcart b/t/t4018/java-return-generic-wildcart
new file mode 100644
index 0000000000..2d682e1e2b
--- /dev/null
+++ b/t/t4018/java-return-generic-wildcart
@@ -0,0 +1,6 @@
+class MyExample {
+    public List<? extends Comparable> myMethod(String[] RIGHT) {
+        // Whatever...
+        return Arrays.asList("ChangeMe");
+    }
+}
diff --git a/t/t4018/java-return-generic2 b/t/t4018/java-return-generic2
new file mode 100644
index 0000000000..7109c27456
--- /dev/null
+++ b/t/t4018/java-return-generic2
@@ -0,0 +1,6 @@
+class MyExample {
+    public <T> List<T> myMethod(T[] RIGHT) {
+        // Whatever...
+        return (List<T>) Arrays.asList("ChangeMe");
+    }
+}
diff --git a/t/t4018/java-return-generic3 b/t/t4018/java-return-generic3
new file mode 100644
index 0000000000..849f116f50
--- /dev/null
+++ b/t/t4018/java-return-generic3
@@ -0,0 +1,6 @@
+class MyExample {
+    public <AType, B> Map<AType, B> myMethod(String[] RIGHT) {
+        // Whatever...
+        return new java.util.HashMap<>(); // ChangeMe
+    }
+}
diff --git a/t/t4018/java-return-generic4 b/t/t4018/java-return-generic4
new file mode 100644
index 0000000000..1b22c8c037
--- /dev/null
+++ b/t/t4018/java-return-generic4
@@ -0,0 +1,6 @@
+class MyExample {
+    public <AType, B> java.util.Map<AType, Map<B, B[]>> myMethod(String[] RIGHT) {
+        // Whatever...
+        return new java.util.HashMap<>(); // ChangeMe
+    }
+}
diff --git a/userdiff.c b/userdiff.c
index 3c3bbe38b0..9bd751b7d2 100644
--- a/userdiff.c
+++ b/userdiff.c
@@ -142,7 +142,28 @@ PATTERNS("html",
 	 "[^<>= \t]+"),
 PATTERNS("java",
 	 "!^[ \t]*(catch|do|for|if|instanceof|new|return|switch|throw|while)\n"
-	 "^[ \t]*(([A-Za-z_][A-Za-z_0-9]*[ \t]+)+[A-Za-z_][A-Za-z_0-9]*[ \t]*\\([^;]*)$",
+         "^[ \t]*("
+         /* Class, enum, and interface declarations: */
+         /*   optional modifiers: public */
+         "(([a-z]+[ \t]+)*"
+         /*   the kind of declaration */
+         "(class|enum|interface)[ \t]+"
+         /*   the name */
+         "[A-Za-z][A-Za-z0-9_$]*[ \t]+.*)"
+         /* Method & constructor signatures: */
+         /*   optional modifiers: public static */
+         "|(([a-z]+[ \t]+)*"
+         /*   type params and return types for methods but not constructors */
+         "("
+         /*     optional type parameters: <A, B extends Comparable<B>> */
+         "(<[A-Za-z0-9_,.&<> \t]+>[ \t]+)?"
+         /*     return type: java.util.Map<A, B[]> or List<?> */
+         "([A-Za-z_]([A-Za-z_0-9<>,.?]|\\[[ \t]*\\])*[ \t]+)+"
+         /*   end of type params and return type */
+         ")?"
+         /*   the method name followed by the parameter list: myMethod(...) */
+         "[A-Za-z_][A-Za-z_0-9]*[ \t]*\\([^;]*)"
+         ")$",
 	 /* -- */
 	 "[a-zA-Z_][a-zA-Z0-9_]*"
 	 "|[-+0-9.e]+[fFlL]?|0[xXbB]?[0-9a-fA-F]+[lL]?"
-- 
2.32.0