use crate::utils::paths;
use crate::utils::{
- in_macro_or_desugar, is_expn_of, last_path_segment, match_def_path, match_type, resolve_node, snippet,
+ is_expn_of, is_type_diagnostic_item, last_path_segment, match_def_path, match_function_call, 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_lint_pass, declare_tool_lint};
+use rustc_ast::ast::LitKind;
use rustc_errors::Applicability;
-use syntax::ast::LitKind;
-use syntax::source_map::Span;
+use rustc_hir::{Arm, BorrowKind, Expr, ExprKind, MatchSource, PatKind};
+use rustc_lint::{LateContext, LateLintPass, LintContext};
+use rustc_session::{declare_lint_pass, declare_tool_lint};
+use rustc_span::source_map::Span;
declare_clippy_lint! {
/// **What it does:** Checks for the use of `format!("string literal with no
///
/// **Examples:**
/// ```rust
+ ///
+ /// // Bad
/// # let foo = "foo";
- /// format!("foo");
/// format!("{}", foo);
+ ///
+ /// // Good
+ /// format!("foo");
/// ```
pub USELESS_FORMAT,
complexity,
declare_lint_pass!(UselessFormat => [USELESS_FORMAT]);
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_or_desugar(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) = resolve_node(cx, qpath, fun.hir_id).opt_def_id();
- let new_v1 = match_def_path(cx, fun_def_id, &paths::FMT_ARGUMENTS_NEWV1);
- let new_v1_fmt = match_def_path(cx,
- 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().as_symbol() == sym!(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>")))
- }
- };
+ fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr<'_>) {
+ 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 actual_snippet = snippet(cx, expr.span, "<expr>").to_string();
- let actual_snippet = actual_snippet.replace("{{}}", "{}");
- let sugg = format!("{}.to_string()", actual_snippet);
- 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);
}
}
}
sugg.push(';');
}
- span_lint_and_then(cx, USELESS_FORMAT, span, "useless use of `format!`", |db| {
- db.span_suggestion(
+ span_lint_and_then(cx, USELESS_FORMAT, span, "useless use of `format!`", |diag| {
+ diag.span_suggestion(
to_replace,
help,
sugg,
});
}
-/// 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: &'tcx [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(BorrowKind::Ref, _, ref format_args) = expr.kind;
+ if let ExprKind::Array(ref elems) = arms[0].body.kind;
+ if elems.len() == 1;
+ if let Some(args) = match_function_call(cx, &elems[0], &paths::FMT_ARGUMENTV1_NEW);
+ // matches `core::fmt::Display::fmt`
+ if args.len() == 2;
+ if let ExprKind::Path(ref qpath) = args[1].kind;
+ if let Some(did) = cx.tables().qpath_res(qpath, args[1].hir_id).opt_def_id();
+ if match_def_path(cx, did, &paths::DISPLAY_FMT_METHOD);
+ // check `(arg0,)` in match block
+ if let PatKind::Tuple(ref pats, None) = arms[0].pat.kind;
+ if pats.len() == 1;
then {
- return lit.as_str().is_empty();
+ let ty = walk_ptrs_ty(cx.tables().pat_ty(&pats[0]));
+ if ty.kind != rustc_middle::ty::Str && !is_type_diagnostic_item(cx, ty, sym!(string_type)) {
+ return None;
+ }
+ if let ExprKind::Lit(ref lit) = format_args.kind {
+ 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.kind {
+ if path.ident.name == sym!(to_string) {
+ return Some(format!("{}", snip));
+ }
+ } else if let ExprKind::Binary(..) = format_args.kind {
+ 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 Some(args) = match_function_call(cx, expr, &paths::FMT_ARGUMENTS_NEW_V1);
if args.len() == 2;
- if let ExprKind::Path(ref qpath) = args[1].node;
- if let Some(fun_def_id) = resolve_node(cx, qpath, args[1].hir_id).opt_def_id();
- if match_def_path(cx, fun_def_id, &paths::DISPLAY_FMT_METHOD);
+ // Argument 1 in `new_v1()`
+ if let ExprKind::AddrOf(BorrowKind::Ref, _, ref arr) = args[0].kind;
+ if let ExprKind::Array(ref pieces) = arr.kind;
+ if pieces.len() == 1;
+ if let ExprKind::Lit(ref lit) = pieces[0].kind;
+ if let LitKind::Str(ref s, _) = lit.node;
+ // Argument 2 in `new_v1()`
+ if let ExprKind::AddrOf(BorrowKind::Ref, _, ref arg1) = args[1].kind;
+ if let ExprKind::Match(ref matchee, ref arms, MatchSource::Normal) = arg1.kind;
+ if arms.len() == 1;
+ if let ExprKind::Tup(ref tup) = matchee.kind;
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 Some(args) = match_function_call(cx, expr, &paths::FMT_ARGUMENTS_NEW_V1_FORMATTED);
+ if args.len() == 3;
+ if check_unformatted(&args[2]);
+ // Argument 1 in `new_v1_formatted()`
+ if let ExprKind::AddrOf(BorrowKind::Ref, _, ref arr) = args[0].kind;
+ if let ExprKind::Array(ref pieces) = arr.kind;
+ if pieces.len() == 1;
+ if let ExprKind::Lit(ref lit) = pieces[0].kind;
+ if let LitKind::Str(..) = lit.node;
+ // Argument 2 in `new_v1_formatted()`
+ if let ExprKind::AddrOf(BorrowKind::Ref, _, ref arg1) = args[1].kind;
+ if let ExprKind::Match(ref matchee, ref arms, MatchSource::Normal) = arg1.kind;
+ if arms.len() == 1;
+ if let ExprKind::Tup(ref tup) = matchee.kind;
+ then {
+ return on_argumentv1_new(cx, &tup[0], arms);
+ }
+ }
None
}
/// &[_ {
/// format: _ {
/// width: _::Implied,
+/// precision: _::Implied,
/// ...
/// },
/// ...,
/// }]
/// ```
-fn check_unformatted(expr: &Expr) -> bool {
+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 let ExprKind::AddrOf(BorrowKind::Ref, _, ref expr) = expr.kind;
+ if let ExprKind::Array(ref exprs) = expr.kind;
if exprs.len() == 1;
- if let ExprKind::Struct(_, ref fields, _) = exprs[0].node;
+ // struct `core::fmt::rt::v1::Argument`
+ if let ExprKind::Struct(_, ref fields, _) = exprs[0].kind;
if let Some(format_field) = fields.iter().find(|f| f.ident.name == sym!(format));
- if let ExprKind::Struct(_, ref fields, _) = format_field.expr.node;
- 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);
+ // struct `core::fmt::rt::v1::FormatSpec`
+ if let ExprKind::Struct(_, ref fields, _) = format_field.expr.kind;
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 let ExprKind::Path(ref precision_path) = precision_field.expr.kind;
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.kind;
+ if last_path_segment(width_qpath).ident.name == sym!(Implied);
then {
return true;
}
projects / rust.git / blobdiff