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,
+ is_expn_of, last_path_segment, match_def_path, match_type, resolve_node, snippet, span_lint_and_then, walk_ptrs_ty,
};
use if_chain::if_chain;
use rustc::hir::*;
use rustc::lint::{LateContext, LateLintPass, LintArray, LintContext, LintPass};
-use rustc::ty;
-use rustc::{declare_tool_lint, lint_array};
+use rustc::{declare_lint_pass, declare_tool_lint};
use rustc_errors::Applicability;
use syntax::ast::LitKind;
use syntax::source_map::Span;
///
/// **Examples:**
/// ```rust
- /// format!("foo")
- /// format!("{}", foo)
+ /// # let foo = "foo";
+ /// format!("foo");
+ /// format!("{}", foo);
/// ```
pub USELESS_FORMAT,
complexity,
"useless use of `format!`"
}
-#[derive(Copy, Clone, Debug)]
-pub struct Pass;
+declare_lint_pass!(UselessFormat => [USELESS_FORMAT]);
-impl LintPass for Pass {
- fn get_lints(&self) -> LintArray {
- lint_array![USELESS_FORMAT]
- }
-
- fn name(&self) -> &'static str {
- "UselessFormat"
- }
-}
-
-impl<'a, 'tcx> LateLintPass<'a, 'tcx> for Pass {
+impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UselessFormat {
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
- ExprKind::Call(ref fun, ref args) => {
- if_chain! {
- if let ExprKind::Path(ref qpath) = fun.node;
- if let Some(fun_def_id) = opt_def_id(resolve_node(cx, qpath, fun.hir_id));
- let new_v1 = match_def_path(cx.tcx, fun_def_id, &paths::FMT_ARGUMENTS_NEWV1);
- let new_v1_fmt = match_def_path(
- cx.tcx,
- fun_def_id,
- &paths::FMT_ARGUMENTS_NEWV1FORMATTED
- );
- if new_v1 || new_v1_fmt;
- if check_single_piece(&args[0]);
- if let Some(format_arg) = get_single_string_arg(cx, &args[1]);
- if new_v1 || check_unformatted(&args[2]);
- if let ExprKind::AddrOf(_, ref format_arg) = format_arg.node;
- then {
- let (message, sugg) = if_chain! {
- if let ExprKind::MethodCall(ref path, _, _) = format_arg.node;
- if path.ident.as_interned_str() == "to_string";
- then {
- ("`to_string()` is enough",
- snippet(cx, format_arg.span, "<arg>").to_string())
- } else {
- ("consider using .to_string()",
- format!("{}.to_string()", snippet(cx, format_arg.span, "<arg>")))
- }
- };
+ let span = match is_expn_of(expr.span, "format") {
+ Some(s) if !s.from_expansion() => s,
+ _ => return,
+ };
- span_useless_format(cx, span, message, sugg);
- }
- }
- },
- // `format!("foo")` expansion contains `match () { () => [], }`
- ExprKind::Match(ref matchee, _, _) => {
- if let ExprKind::Tup(ref tup) = matchee.node {
- if tup.is_empty() {
- let sugg = format!("{}.to_string()", snippet(cx, expr.span, "<expr>").into_owned());
- span_useless_format(cx, span, "consider using .to_string()", sugg);
- }
- }
- },
- _ => (),
- }
+ // Operate on the only argument of `alloc::fmt::format`.
+ if let Some(sugg) = on_new_v1(cx, expr) {
+ span_useless_format(cx, span, "consider using .to_string()", sugg);
+ } else if let Some(sugg) = on_new_v1_fmt(cx, expr) {
+ span_useless_format(cx, span, "consider using .to_string()", sugg);
}
}
}
-fn span_useless_format<'a, 'tcx: 'a, T: LintContext<'tcx>>(cx: &'a T, span: Span, help: &str, mut sugg: String) {
+fn span_useless_format<T: LintContext>(cx: &T, span: Span, help: &str, mut sugg: String) {
let to_replace = span.source_callsite();
// The callsite span contains the statement semicolon for some reason.
});
}
-/// Checks if the expressions matches `&[""]`
-fn check_single_piece(expr: &Expr) -> bool {
+fn on_argumentv1_new<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr, arms: &'a [Arm]) -> Option<String> {
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::Lit(ref lit) = exprs[0].node;
- if let LitKind::Str(ref lit, _) = lit.node;
+ if let ExprKind::AddrOf(_, ref format_args) = expr.node;
+ if let ExprKind::Array(ref elems) = arms[0].body.node;
+ if elems.len() == 1;
+ if let ExprKind::Call(ref fun, ref args) = elems[0].node;
+ if let ExprKind::Path(ref qpath) = fun.node;
+ if let Some(did) = resolve_node(cx, qpath, fun.hir_id).opt_def_id();
+ if match_def_path(cx, did, &paths::FMT_ARGUMENTV1_NEW);
+ // matches `core::fmt::Display::fmt`
+ if args.len() == 2;
+ if let ExprKind::Path(ref qpath) = args[1].node;
+ if let Some(did) = resolve_node(cx, qpath, args[1].hir_id).opt_def_id();
+ if match_def_path(cx, did, &paths::DISPLAY_FMT_METHOD);
+ if arms[0].pats.len() == 1;
+ // check `(arg0,)` in match block
+ if let PatKind::Tuple(ref pats, None) = arms[0].pats[0].node;
+ if pats.len() == 1;
then {
- return lit.as_str().is_empty();
+ let ty = walk_ptrs_ty(cx.tables.pat_ty(&pats[0]));
+ if ty.sty != rustc::ty::Str && !match_type(cx, ty, &paths::STRING) {
+ return None;
+ }
+ if let ExprKind::Lit(ref lit) = format_args.node {
+ if let LitKind::Str(ref s, _) = lit.node {
+ return Some(format!("{:?}.to_string()", s.as_str()));
+ }
+ } else {
+ let snip = snippet(cx, format_args.span, "<arg>");
+ if let ExprKind::MethodCall(ref path, _, _) = format_args.node {
+ if path.ident.name == sym!(to_string) {
+ return Some(format!("{}", snip));
+ }
+ } else if let ExprKind::Binary(..) = format_args.node {
+ return Some(format!("{}", snip));
+ }
+ return Some(format!("{}.to_string()", snip));
+ }
}
}
-
- false
+ None
}
-/// Checks if the expressions matches
-/// ```rust,ignore
-/// &match (&"arg",) {
-/// (__arg0,) => [::std::fmt::ArgumentV1::new(__arg0,
-/// ::std::fmt::Display::fmt)],
-/// }
-/// ```
-/// and that the type of `__arg0` is `&str` or `String`,
-/// then returns the span of first element of the matched tuple.
-fn get_single_string_arg<'a>(cx: &LateContext<'_, '_>, expr: &'a Expr) -> Option<&'a Expr> {
+fn on_new_v1<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr) -> Option<String> {
if_chain! {
- 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 ExprKind::Array(ref exprs) = arms[0].body.node;
- if exprs.len() == 1;
- if let ExprKind::Call(_, ref args) = exprs[0].node;
+ if let ExprKind::Call(ref fun, ref args) = expr.node;
if args.len() == 2;
- 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);
+ if let ExprKind::Path(ref qpath) = fun.node;
+ if let Some(did) = resolve_node(cx, qpath, fun.hir_id).opt_def_id();
+ if match_def_path(cx, did, &paths::FMT_ARGUMENTS_NEW_V1);
+ // Argument 1 in `new_v1()`
+ if let ExprKind::AddrOf(_, ref arr) = args[0].node;
+ if let ExprKind::Array(ref pieces) = arr.node;
+ if pieces.len() == 1;
+ if let ExprKind::Lit(ref lit) = pieces[0].node;
+ if let LitKind::Str(ref s, _) = lit.node;
+ // Argument 2 in `new_v1()`
+ if let ExprKind::AddrOf(_, ref arg1) = args[1].node;
+ if let ExprKind::Match(ref matchee, ref arms, MatchSource::Normal) = arg1.node;
+ if arms.len() == 1;
+ if let ExprKind::Tup(ref tup) = matchee.node;
then {
- let ty = walk_ptrs_ty(cx.tables.pat_ty(&pat[0]));
- if ty.sty == ty::Str || match_type(cx, ty, &paths::STRING) {
- if let ExprKind::Tup(ref values) = match_expr.node {
- return Some(&values[0]);
- }
+ // `format!("foo")` expansion contains `match () { () => [], }`
+ if tup.is_empty() {
+ return Some(format!("{:?}.to_string()", s.as_str()));
+ } else if s.as_str().is_empty() {
+ return on_argumentv1_new(cx, &tup[0], arms);
}
}
}
+ None
+}
+fn on_new_v1_fmt<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr) -> Option<String> {
+ if_chain! {
+ if let ExprKind::Call(ref fun, ref args) = expr.node;
+ if args.len() == 3;
+ if let ExprKind::Path(ref qpath) = fun.node;
+ if let Some(did) = resolve_node(cx, qpath, fun.hir_id).opt_def_id();
+ if match_def_path(cx, did, &paths::FMT_ARGUMENTS_NEW_V1_FORMATTED);
+ if check_unformatted(&args[2]);
+ // Argument 1 in `new_v1_formatted()`
+ if let ExprKind::AddrOf(_, ref arr) = args[0].node;
+ if let ExprKind::Array(ref pieces) = arr.node;
+ if pieces.len() == 1;
+ if let ExprKind::Lit(ref lit) = pieces[0].node;
+ if let LitKind::Str(..) = lit.node;
+ // Argument 2 in `new_v1_formatted()`
+ if let ExprKind::AddrOf(_, ref arg1) = args[1].node;
+ if let ExprKind::Match(ref matchee, ref arms, MatchSource::Normal) = arg1.node;
+ if arms.len() == 1;
+ if let ExprKind::Tup(ref tup) = matchee.node;
+ then {
+ return on_argumentv1_new(cx, &tup[0], arms);
+ }
+ }
None
}
/// &[_ {
/// format: _ {
/// width: _::Implied,
+/// precision: _::Implied,
/// ...
/// },
/// ...,
if let ExprKind::AddrOf(_, ref expr) = expr.node;
if let ExprKind::Array(ref exprs) = expr.node;
if exprs.len() == 1;
+ // struct `core::fmt::rt::v1::Argument`
if let ExprKind::Struct(_, ref fields, _) = exprs[0].node;
- if let Some(format_field) = fields.iter().find(|f| f.ident.name == "format");
+ if let Some(format_field) = fields.iter().find(|f| f.ident.name == sym!(format));
+ // struct `core::fmt::rt::v1::FormatSpec`
if let ExprKind::Struct(_, ref fields, _) = format_field.expr.node;
- if let Some(width_field) = fields.iter().find(|f| f.ident.name == "width");
- if let ExprKind::Path(ref width_qpath) = width_field.expr.node;
- if last_path_segment(width_qpath).ident.name == "Implied";
- if let Some(precision_field) = fields.iter().find(|f| f.ident.name == "precision");
+ if let Some(precision_field) = fields.iter().find(|f| f.ident.name == sym!(precision));
if let ExprKind::Path(ref precision_path) = precision_field.expr.node;
- if last_path_segment(precision_path).ident.name == "Implied";
+ if last_path_segment(precision_path).ident.name == sym!(Implied);
+ if let Some(width_field) = fields.iter().find(|f| f.ident.name == sym!(width));
+ if let ExprKind::Path(ref width_qpath) = width_field.expr.node;
+ if last_path_segment(width_qpath).ident.name == sym!(Implied);
then {
return true;
}
projects / rust.git / blobdiff