[PATCH] RFC: userdiff: add built-in pattern for rust

[marcandre.lureau@redhat.com]

From: Marc-André Lureau <mlureau@redhat.com>

This adds xfuncname and word_regex patterns for Rust, a quite
popular programming language. It also includes test cases for the
xfuncname regex (t4018) and updated documentation.

The word_regex pattern finds identifiers, integers, floats and
operators, according to the Rust Reference Book.

RFC: since I don't understand why when there are extra lines such as the
one with FIXME, the funcname is not correctly reported. Help welcome!

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
---
 Documentation/gitattributes.txt | 2 ++
 t/t4018-diff-funcname.sh        | 1 +
 t/t4018/rust-fn                 | 5 +++++
 t/t4018/rust-struct             | 5 +++++
 t/t4018/rust-trait              | 5 +++++
 userdiff.c                      | 9 +++++++++
 6 files changed, 27 insertions(+)
 create mode 100644 t/t4018/rust-fn
 create mode 100644 t/t4018/rust-struct
 create mode 100644 t/t4018/rust-trait

diff --git a/Documentation/gitattributes.txt b/Documentation/gitattributes.txt
index 4fb20cd0e9..07da08fb27 100644
--- a/Documentation/gitattributes.txt
+++ b/Documentation/gitattributes.txt
@@ -833,6 +833,8 @@ patterns are available:
 
 - `ruby` suitable for source code in the Ruby language.
 
+- `rust` suitable for source code in the Rust language.
+
 - `tex` suitable for source code for LaTeX documents.
 
 
diff --git a/t/t4018-diff-funcname.sh b/t/t4018-diff-funcname.sh
index 22f9f88f0a..9261d6d3a0 100755
--- a/t/t4018-diff-funcname.sh
+++ b/t/t4018-diff-funcname.sh
@@ -43,6 +43,7 @@ diffpatterns="
 	php
 	python
 	ruby
+	rust
 	tex
 	custom1
 	custom2
diff --git a/t/t4018/rust-fn b/t/t4018/rust-fn
new file mode 100644
index 0000000000..f450590d6c
--- /dev/null
+++ b/t/t4018/rust-fn
@@ -0,0 +1,5 @@
+pub(self) fn RIGHT<T>(x: &[T]) where T: Debug {
+    let _ = x;
+    // FIXME: extra lines break match?
+    let a = ChangeMe;
+}
diff --git a/t/t4018/rust-struct b/t/t4018/rust-struct
new file mode 100644
index 0000000000..76aff1c0d8
--- /dev/null
+++ b/t/t4018/rust-struct
@@ -0,0 +1,5 @@
+#[derive(Debug)]
+pub(super) struct RIGHT<'a> {
+    name: &'a str,
+    age: ChangeMe,
+}
diff --git a/t/t4018/rust-trait b/t/t4018/rust-trait
new file mode 100644
index 0000000000..ea397f09ed
--- /dev/null
+++ b/t/t4018/rust-trait
@@ -0,0 +1,5 @@
+unsafe trait RIGHT<T> {
+    fn len(&self) -> u32;
+    fn ChangeMe(&self, n: u32) -> T;
+    fn iter<F>(&self, f: F) where F: Fn(T);
+}
diff --git a/userdiff.c b/userdiff.c
index 3a78fbf504..9e1e2fa03f 100644
--- a/userdiff.c
+++ b/userdiff.c
@@ -130,6 +130,15 @@ PATTERNS("ruby", "^[ \t]*((class|module|def)[ \t].*)$",
 	 "(@|@@|\\$)?[a-zA-Z_][a-zA-Z0-9_]*"
 	 "|[-+0-9.e]+|0[xXbB]?[0-9a-fA-F]+|\\?(\\\\C-)?(\\\\M-)?."
 	 "|//=?|[-+*/<>%&^|=!]=|<<=?|>>=?|===|\\.{1,3}|::|[!=]~"),
+PATTERNS("rust",
+	 "^[\t ]*(((pub|pub\\([^)]+\\))[\t ]+)?(struct|enum|union|mod)[ \t].*)$\n"
+	 "^[\t ]*(((pub|pub\\([^)]+\\))[\t ]+)?(unsafe[\t ]+)?trait[ \t].*)$\n"
+	 "^[\t ]*(((pub|pub\\([^)]+\\))[\t ]+)?((const|unsafe|extern(([\t ]+)*\"[^)]+\")?)[\t ]+)*fn[ \t].*)$\n",
+	 /* -- */
+	 "[a-zA-Z_][a-zA-Z0-9_]*"
+	 "|[-+_0-9.eE]+(f32|f64|u8|u16|u32|u64|u128|usize|i8|i16|i32|i64|i128|isize)?"
+	 "|0[box]?[0-9a-fA-F_]+(u8|u16|u32|u64|u128|usize|i8|i16|i32|i64|i128|isize)?"
+	 "|[-+*\\/<>%&^|=!:]=|<<=?|>>=?|&&|\\|\\||->|=>|\\.{2}=|\\.{3}|::"),
 PATTERNS("bibtex", "(@[a-zA-Z]{1,}[ \t]*\\{{0,1}[ \t]*[^ \t\"@',\\#}{~%]*).*$",
 	 "[={}\"]|[^={}\" \t]+"),
 PATTERNS("tex", "^(\\\\((sub)*section|chapter|part)\\*{0,1}\\{.*)$",

base-commit: ab15ad1a3b4b04a29415aef8c9afa2f64fc194a2
-- 
2.22.0.rc0.1.g4f1097ba08