use rustc::hir::*;
use rustc::lint::*;
+use rustc::{declare_lint, lint_array};
+use if_chain::if_chain;
use rustc::ty;
use syntax::ast::LitKind;
-use utils::paths;
-use utils::{is_expn_of, match_def_path, match_type, resolve_node, span_lint, walk_ptrs_ty, opt_def_id};
+use syntax_pos::Span;
+use crate::utils::paths;
+use crate::utils::{in_macro, is_expn_of, last_path_segment, match_def_path, match_type, opt_def_id, resolve_node, snippet, span_lint_and_then, walk_ptrs_ty};
/// **What it does:** Checks for the use of `format!("string literal with no
/// argument")` and `format!("{}", foo)` where `foo` is a string.
/// format!("foo")
/// format!("{}", foo)
/// ```
-declare_lint! {
+declare_clippy_lint! {
pub USELESS_FORMAT,
- Warn,
+ complexity,
"useless use of `format!`"
}
impl<'a, 'tcx> LateLintPass<'a, 'tcx> for Pass {
fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr) {
if let Some(span) = is_expn_of(expr.span, "format") {
+ if in_macro(span) {
+ return;
+ }
match expr.node {
+
// `format!("{}", foo)` expansion
- ExprCall(ref fun, ref args) => {
+ ExprKind::Call(ref fun, ref args) => {
if_chain! {
- if let ExprPath(ref qpath) = fun.node;
- if args.len() == 2;
+ if let ExprKind::Path(ref qpath) = fun.node;
+ if args.len() == 3;
if let Some(fun_def_id) = opt_def_id(resolve_node(cx, qpath, fun.hir_id));
- if match_def_path(cx.tcx, fun_def_id, &paths::FMT_ARGUMENTS_NEWV1);
- // ensure the format string is `"{..}"` with only one argument and no text
- if check_static_str(&args[0]);
- // ensure the format argument is `{}` ie. Display with no fancy option
- // and that the argument is a string
- if check_arg_is_display(cx, &args[1]);
+ if match_def_path(cx.tcx, fun_def_id, &paths::FMT_ARGUMENTS_NEWV1FORMATTED);
+ if check_single_piece(&args[0]);
+ if let Some(format_arg) = get_single_string_arg(cx, &args[1]);
+ if check_unformatted(&args[2]);
then {
- span_lint(cx, USELESS_FORMAT, span, "useless use of `format!`");
+ let sugg = format!("{}.to_string()", snippet(cx, format_arg, "<arg>").into_owned());
+ span_lint_and_then(cx, USELESS_FORMAT, span, "useless use of `format!`", |db| {
+ db.span_suggestion(expr.span, "consider using .to_string()", sugg);
+ });
}
}
},
// `format!("foo")` expansion contains `match () { () => [], }`
- ExprMatch(ref matchee, _, _) => if let ExprTup(ref tup) = matchee.node {
+ ExprKind::Match(ref matchee, _, _) => if let ExprKind::Tup(ref tup) = matchee.node {
if tup.is_empty() {
- span_lint(cx, USELESS_FORMAT, span, "useless use of `format!`");
+ let sugg = format!("{}.to_string()", snippet(cx, expr.span, "<expr>").into_owned());
+ span_lint_and_then(cx, USELESS_FORMAT, span, "useless use of `format!`", |db| {
+ db.span_suggestion(span, "consider using .to_string()", sugg);
+ });
}
},
_ => (),
}
/// Checks if the expressions matches `&[""]`
-fn check_static_str(expr: &Expr) -> bool {
+fn check_single_piece(expr: &Expr) -> bool {
if_chain! {
- if let ExprAddrOf(_, ref expr) = expr.node; // &[""]
- if let ExprArray(ref exprs) = expr.node; // [""]
+ if let ExprKind::AddrOf(_, ref expr) = expr.node; // &[""]
+ if let ExprKind::Array(ref exprs) = expr.node; // [""]
if exprs.len() == 1;
- if let ExprLit(ref lit) = exprs[0].node;
+ if let ExprKind::Lit(ref lit) = exprs[0].node;
if let LitKind::Str(ref lit, _) = lit.node;
then {
return lit.as_str().is_empty();
/// Checks if the expressions matches
/// ```rust,ignore
-/// &match (&42,) {
+/// &match (&"arg",) {
/// (__arg0,) => [::std::fmt::ArgumentV1::new(__arg0,
/// ::std::fmt::Display::fmt)],
/// }
/// ```
-fn check_arg_is_display(cx: &LateContext, expr: &Expr) -> bool {
+/// and that type of `__arg0` is `&str` or `String`
+/// then returns the span of first element of the matched tuple
+fn get_single_string_arg(cx: &LateContext, expr: &Expr) -> Option<Span> {
if_chain! {
- if let ExprAddrOf(_, ref expr) = expr.node;
- if let ExprMatch(_, ref arms, _) = expr.node;
+ if let ExprKind::AddrOf(_, ref expr) = expr.node;
+ if let ExprKind::Match(ref match_expr, ref arms, _) = expr.node;
if arms.len() == 1;
if arms[0].pats.len() == 1;
if let PatKind::Tuple(ref pat, None) = arms[0].pats[0].node;
if pat.len() == 1;
- if let ExprArray(ref exprs) = arms[0].body.node;
+ if let ExprKind::Array(ref exprs) = arms[0].body.node;
if exprs.len() == 1;
- if let ExprCall(_, ref args) = exprs[0].node;
+ if let ExprKind::Call(_, ref args) = exprs[0].node;
if args.len() == 2;
- if let ExprPath(ref qpath) = args[1].node;
+ if let ExprKind::Path(ref qpath) = args[1].node;
if let Some(fun_def_id) = opt_def_id(resolve_node(cx, qpath, args[1].hir_id));
if match_def_path(cx.tcx, fun_def_id, &paths::DISPLAY_FMT_METHOD);
then {
let ty = walk_ptrs_ty(cx.tables.pat_ty(&pat[0]));
-
- return ty.sty == ty::TyStr || match_type(cx, ty, &paths::STRING);
+ if ty.sty == ty::TyStr || match_type(cx, ty, &paths::STRING) {
+ if let ExprKind::Tup(ref values) = match_expr.node {
+ return Some(values[0].span);
+ }
+ }
+ }
+ }
+
+ None
+}
+
+/// Checks if the expression matches
+/// ```rust,ignore
+/// &[_ {
+/// format: _ {
+/// width: _::Implied,
+/// ...
+/// },
+/// ...,
+/// }]
+/// ```
+fn check_unformatted(expr: &Expr) -> bool {
+ if_chain! {
+ if let ExprKind::AddrOf(_, ref expr) = expr.node;
+ if let ExprKind::Array(ref exprs) = expr.node;
+ if exprs.len() == 1;
+ if let ExprKind::Struct(_, ref fields, _) = exprs[0].node;
+ if let Some(format_field) = fields.iter().find(|f| f.ident.name == "format");
+ if let ExprKind::Struct(_, ref fields, _) = format_field.expr.node;
+ if let Some(align_field) = fields.iter().find(|f| f.ident.name == "width");
+ if let ExprKind::Path(ref qpath) = align_field.expr.node;
+ if last_path_segment(qpath).ident.name == "Implied";
+ then {
+ return true;
}
}
projects / rust.git / blobdiff