Swap Msrv from Vec to SmallVec

Author: GnomedDev

clippy_config/src/lib.rs

@@ -20,6 +20,7 @@ extern crate rustc_driver;
 externcrate rustc_errors;
 externcrate rustc_session;
 externcrate rustc_span;
+externcrate smallvec;
 
 mod conf;
 mod metadata;

clippy_config/src/msrvs.rs

@@ -3,6 +3,7 @@ use rustc_attr::parse_version;
 use rustc_session::{RustcVersion,Session};
 use rustc_span::{Symbol, sym};
 use serde::Deserialize;
+use smallvec::{SmallVec, smallvec};
 use std::fmt;
 
 macro_rules! msrv_aliases {
@@ -67,7 +68,7 @@ msrv_aliases! {
 /// Tracks the current MSRV from `clippy.toml`, `Cargo.toml` or set via `#[clippy::msrv]`
 #[derive(Debug,Clone)]
 pubstructMsrv{
-stack:Vec<RustcVersion>,
+stack:SmallVec<[RustcVersion;2]>,
 }
 
 impl fmt::DisplayforMsrv{
@@ -87,14 +88,14 @@ impl<'de> Deserialize<'de> for Msrv {
 {
 let v = String::deserialize(deserializer)?;
 parse_version(Symbol::intern(&v))
-.map(|v| Msrv{stack:vec![v]})
+.map(|v| Msrv{stack:smallvec![v]})
 .ok_or_else(|| serde::de::Error::custom("not a valid Rust version"))
 }
 }
 
 implMsrv{
 pubfnempty() -> Msrv{
-Msrv{stack:Vec::new()}
+Msrv{stack:SmallVec::new()}
 }
 
 pubfnread_cargo(&mutself,sess:&Session){
@@ -103,7 +104,7 @@ impl Msrv {
 .and_then(|v| parse_version(Symbol::intern(&v)));
 
 match(self.current(), cargo_msrv){
-(None,Some(cargo_msrv)) => self.stack = vec![cargo_msrv],
+(None,Some(cargo_msrv)) => self.stack = smallvec![cargo_msrv],
 (Some(clippy_msrv),Some(cargo_msrv)) => {
 if clippy_msrv != cargo_msrv {
  sess.dcx().warn(format!(