userdiff: extend Bash pattern to cover more shell function forms

The previous function regex required explicit matching of function
bodies using `{`, `(`, `((`, or `[[`, which caused several issues:

- It failed to capture valid functions where `{` was on the next line
  due to line continuation (`\`).
- It did not recognize functions with single  command body, such as
  `x () echo hello`.

Replacing the function body matching logic with `.*$`, ensures
that everything on the function definition line is captured.

Additionally, the word regex is refined to better recognize shell
syntax, including additional parameter expansion operators and
command-line options.

Signed-off-by: Moumita Dhar <dhar61595@gmail.com>
Acked-by: Johannes Sixt <j6t@kdbg.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 3 insertions, 0 deletions

diff --git a/t/t4018/bash-posix-style-single-command-function b/t/t4018/bash-posix-style-single-command-function
new file mode 100644
index 0000000000..398ae1c5d2
--- /dev/null
+++ b/t/t4018/bash-posix-style-single-command-function
@@ -0,0 +1,3 @@
+RIGHT() echo "hello"
+
+    ChangeMe