-use rustc::hir::*;
-use rustc::lint::{LateContext, LateLintPass, LintArray, LintPass};
-use rustc::{declare_tool_lint, lint_array};
+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,
+};
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_errors::Applicability;
use syntax::ast::LitKind;
-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};
+use syntax::source_map::Span;
/// **What it does:** Checks for the use of `format!("string literal with no
/// argument")` and `format!("{}", foo)` where `foo` is a string.
///
-/// **Why is this bad?** There is no point of doing that. `format!("too")` can
+/// **Why is this bad?** There is no point of doing that. `format!("foo")` can
/// be replaced by `"foo".to_owned()` if you really need a `String`. The even
/// worse `&format!("foo")` is often encountered in the wild. `format!("{}",
/// foo)` can be replaced by `foo.clone()` if `foo: String` or `foo.to_owned()`
fn get_lints(&self) -> LintArray {
lint_array![USELESS_FORMAT]
}
+
+ fn name(&self) -> &'static str {
+ "UselessFormat"
+ }
}
impl<'a, 'tcx> LateLintPass<'a, 'tcx> for Pass {
return;
}
match expr.node {
-
// `format!("{}", foo)` expansion
ExprKind::Call(ref fun, ref args) => {
if_chain! {
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_NEWV1FORMATTED);
+ 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 check_unformatted(&args[2]);
+ if new_v1 || check_unformatted(&args[2]);
+ if let ExprKind::AddrOf(_, ref format_arg) = format_arg.node;
then {
- 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);
- });
+ 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>")))
+ }
+ };
+
+ 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_lint_and_then(cx, USELESS_FORMAT, span, "useless use of `format!`", |db| {
- db.span_suggestion(span, "consider using .to_string()", sugg);
- });
+ 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);
+ }
}
},
_ => (),
}
}
+fn span_useless_format<'a, 'tcx: 'a, T: LintContext<'tcx>>(cx: &'a T, span: Span, help: &str, mut sugg: String) {
+ let to_replace = span.source_callsite();
+
+ // The callsite span contains the statement semicolon for some reason.
+ let snippet = snippet(cx, to_replace, "..");
+ if snippet.ends_with(';') {
+ sugg.push(';');
+ }
+
+ span_lint_and_then(cx, USELESS_FORMAT, span, "useless use of `format!`", |db| {
+ db.span_suggestion(
+ to_replace,
+ help,
+ sugg,
+ Applicability::MachineApplicable, // snippet
+ );
+ });
+}
+
/// Checks if the expressions matches `&[""]`
fn check_single_piece(expr: &Expr) -> bool {
if_chain! {
/// ::std::fmt::Display::fmt)],
/// }
/// ```
-/// 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> {
+/// 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> {
if_chain! {
if let ExprKind::AddrOf(_, ref expr) = expr.node;
if let ExprKind::Match(ref match_expr, ref arms, _) = expr.node;
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].span);
+ return Some(&values[0]);
}
}
}
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";
+ 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 ExprKind::Path(ref precision_path) = precision_field.expr.node;
+ if last_path_segment(precision_path).ident.name == "Implied";
then {
return true;
}
projects / rust.git / blobdiff