rust: fix clippy lint for redundant_closure

Removes a closure where the function can be directly provided.

rust/src/applayer.rs

@@ -678,6 +678,6 @@ pub trait AppLayerFrameType {
 
     /// Converts a variant ID to an FFI safe name.
     extern "C" fn ffi_name_from_id(id: u8) -> *const std::os::raw::c_char where Self: Sized {
-        Self::from_u8(id).map(|s| s.to_cstring()).unwrap_or_else(|| std::ptr::null())
+        Self::from_u8(id).map(|s| s.to_cstring()).unwrap_or_else(std::ptr::null)
     }
 }

rust/src/detect/iprep.rs

@@ -76,7 +76,7 @@ extern "C" {
 
 pub fn detect_parse_iprep(i: &str) -> IResult<&str, DetectIPRepData> {
     let (i, _) = opt(is_a(" "))(i)?;
-    let (i, cmd) = map_res(alpha0, |s: &str| DetectIPRepDataCmd::from_str(s))(i)?;
+    let (i, cmd) = map_res(alpha0, DetectIPRepDataCmd::from_str)(i)?;
     let (i, _) = opt(is_a(" "))(i)?;
     let (i, _) = char(',')(i)?;
     let (i, _) = opt(is_a(" "))(i)?;

rust/src/detect/stream_size.rs

@@ -59,7 +59,7 @@ pub struct DetectStreamSizeData {
 
 pub fn detect_parse_stream_size(i: &str) -> IResult<&str, DetectStreamSizeData> {
     let (i, _) = opt(is_a(" "))(i)?;
-    let (i, flags) = map_res(alpha0, |s: &str| DetectStreamSizeDataFlags::from_str(s))(i)?;
+    let (i, flags) = map_res(alpha0, DetectStreamSizeDataFlags::from_str)(i)?;
     let (i, _) = opt(is_a(" "))(i)?;
     let (i, _) = char(',')(i)?;
     let (i, _) = opt(is_a(" "))(i)?;

rust/src/ike/parser.rs

@@ -471,7 +471,7 @@ pub fn parse_sa_attribute(i: &[u8]) -> IResult<&[u8], Vec<SaAttribute>> {
             },
             hex_value: match format.0 {
                 0 => variable_attribute_value
-                    .map(|_variable_attribute_value| to_hex(_variable_attribute_value)),
+                    .map(to_hex),
                 _ => None,
             },
         };