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camsteffencamsteffen
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Refactor format macro parsing
1 parent 20dbb27 commit e6ab222

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5 files changed

+203
-217
lines changed

5 files changed

+203
-217
lines changed

‎clippy_lints/src/explicit_write.rs‎

Lines changed: 11 additions & 33 deletions
Original file line numberDiff line numberDiff line change
@@ -1,9 +1,9 @@
11
use clippy_utils::diagnostics::{span_lint, span_lint_and_sugg};
2+
use clippy_utils::higher::FormatArgsExpn;
23
use clippy_utils::{is_expn_of, match_function_call, paths};
34
use if_chain::if_chain;
4-
use rustc_ast::ast::LitKind;
55
use rustc_errors::Applicability;
6-
use rustc_hir::{BorrowKind, Expr, ExprKind};
6+
use rustc_hir::{Expr, ExprKind};
77
use rustc_lint::{LateContext, LateLintPass};
88
use rustc_session::{declare_lint_pass, declare_tool_lint};
99
use rustc_span::sym;
@@ -34,29 +34,26 @@ impl<'tcx> LateLintPass<'tcx> for ExplicitWrite {
3434
fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
3535
if_chain! {
3636
// match call to unwrap
37-
if let ExprKind::MethodCall(unwrap_fun, _, unwrap_args, _) = expr.kind;
37+
if let ExprKind::MethodCall(unwrap_fun, _, [write_call], _) = expr.kind;
3838
if unwrap_fun.ident.name == sym::unwrap;
3939
// match call to write_fmt
40-
if !unwrap_args.is_empty();
41-
if let ExprKind::MethodCall(write_fun, _, write_args, _) =
42-
unwrap_args[0].kind;
40+
if let ExprKind::MethodCall(write_fun, _, [write_recv, write_arg], _) = write_call.kind;
4341
if write_fun.ident.name == sym!(write_fmt);
4442
// match calls to std::io::stdout() / std::io::stderr ()
45-
if !write_args.is_empty();
46-
if let Some(dest_name) = if match_function_call(cx, &write_args[0], &paths::STDOUT).is_some() {
43+
if let Some(dest_name) = if match_function_call(cx, write_recv, &paths::STDOUT).is_some() {
4744
Some("stdout")
48-
} else if match_function_call(cx, &write_args[0], &paths::STDERR).is_some() {
45+
} else if match_function_call(cx, write_recv, &paths::STDERR).is_some() {
4946
Some("stderr")
5047
} else {
5148
None
5249
};
50+
if let Some(format_args) = FormatArgsExpn::parse(write_arg);
5351
then {
54-
let write_span = unwrap_args[0].span;
5552
let calling_macro =
5653
// ordering is important here, since `writeln!` uses `write!` internally
57-
if is_expn_of(write_span, "writeln").is_some() {
54+
if is_expn_of(write_call.span, "writeln").is_some() {
5855
Some("writeln")
59-
} else if is_expn_of(write_span, "write").is_some() {
56+
} else if is_expn_of(write_call.span, "write").is_some() {
6057
Some("write")
6158
} else {
6259
None
@@ -70,7 +67,8 @@ impl<'tcx> LateLintPass<'tcx> for ExplicitWrite {
7067
// We need to remove the last trailing newline from the string because the
7168
// underlying `fmt::write` function doesn't know whether `println!` or `print!` was
7269
// used.
73-
if let Some(mut write_output) = write_output_string(write_args) {
70+
if let [write_output] = *format_args.format_string_symbols {
71+
let mut write_output = write_output.to_string();
7472
if write_output.ends_with('\n') {
7573
write_output.pop();
7674
}
@@ -129,23 +127,3 @@ impl<'tcx> LateLintPass<'tcx> for ExplicitWrite {
129127
}
130128
}
131129
}
132-
133-
// Extract the output string from the given `write_args`.
134-
fn write_output_string(write_args: &[Expr<'_>]) -> Option<String> {
135-
if_chain! {
136-
// Obtain the string that should be printed
137-
if write_args.len() > 1;
138-
if let ExprKind::Call(_, output_args) = write_args[1].kind;
139-
if !output_args.is_empty();
140-
if let ExprKind::AddrOf(BorrowKind::Ref, _, output_string_expr) = output_args[0].kind;
141-
if let ExprKind::Array(string_exprs) = output_string_expr.kind;
142-
// we only want to provide an automatic suggestion for simple (non-format) strings
143-
if string_exprs.len() == 1;
144-
if let ExprKind::Lit(ref lit) = string_exprs[0].kind;
145-
if let LitKind::Str(ref write_output, _) = lit.node;
146-
then {
147-
return Some(write_output.to_string())
148-
}
149-
}
150-
None
151-
}

‎clippy_lints/src/format.rs‎

Lines changed: 68 additions & 124 deletions
Original file line numberDiff line numberDiff line change
@@ -1,18 +1,16 @@
1-
use clippy_utils::diagnostics::span_lint_and_then;
2-
use clippy_utils::paths;
3-
use clippy_utils::source::{snippet, snippet_opt};
1+
use clippy_utils::diagnostics::span_lint_and_sugg;
2+
use clippy_utils::higher::FormatExpn;
3+
use clippy_utils::last_path_segment;
4+
use clippy_utils::source::{snippet_opt, snippet_with_applicability};
45
use clippy_utils::sugg::Sugg;
5-
use clippy_utils::ty::is_type_diagnostic_item;
6-
use clippy_utils::{is_expn_of, last_path_segment, match_def_path, match_function_call};
76
use if_chain::if_chain;
8-
use rustc_ast::ast::LitKind;
97
use rustc_errors::Applicability;
10-
use rustc_hir::{Arm, BorrowKind, Expr, ExprKind, MatchSource, PatKind};
11-
use rustc_lint::{LateContext, LateLintPass, LintContext};
8+
use rustc_hir::{BorrowKind, Expr, ExprKind, QPath};
9+
use rustc_lint::{LateContext, LateLintPass};
10+
use rustc_middle::ty;
1211
use rustc_session::{declare_lint_pass, declare_tool_lint};
13-
use rustc_span::source_map::Span;
14-
use rustc_span::sym;
1512
use rustc_span::symbol::kw;
13+
use rustc_span::{sym, Span};
1614

1715
declare_clippy_lint! {
1816
/// **What it does:** Checks for the use of `format!("string literal with no
@@ -45,131 +43,78 @@ declare_lint_pass!(UselessFormat => [USELESS_FORMAT]);
4543

4644
impl<'tcx> LateLintPass<'tcx> for UselessFormat {
4745
fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
48-
let span = match is_expn_of(expr.span, "format") {
49-
Some(s) if !s.from_expansion() => s,
46+
let FormatExpn { call_site, format_args } = match FormatExpn::parse(expr) {
47+
Some(e) if !e.call_site.from_expansion() => e,
5048
_ => return,
5149
};
5250

53-
// Operate on the only argument of `alloc::fmt::format`.
54-
if let Some(sugg) = on_new_v1(cx, expr) {
55-
span_useless_format(cx, span, "consider using `.to_string()`", sugg);
56-
} else if let Some(sugg) = on_new_v1_fmt(cx, expr) {
57-
span_useless_format(cx, span, "consider using `.to_string()`", sugg);
58-
}
59-
}
60-
}
61-
62-
fn span_useless_format<T: LintContext>(cx: &T, span: Span, help: &str, mut sugg: String) {
63-
let to_replace = span.source_callsite();
64-
65-
// The callsite span contains the statement semicolon for some reason.
66-
let snippet = snippet(cx, to_replace, "..");
67-
if snippet.ends_with(';') {
68-
sugg.push(';');
69-
}
70-
71-
span_lint_and_then(cx, USELESS_FORMAT, span, "useless use of `format!`", |diag| {
72-
diag.span_suggestion(
73-
to_replace,
74-
help,
75-
sugg,
76-
Applicability::MachineApplicable, // snippet
77-
);
78-
});
79-
}
80-
81-
fn on_argumentv1_new<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>, arms: &'tcx [Arm<'_>]) -> Option<String> {
82-
if_chain! {
83-
if let ExprKind::AddrOf(BorrowKind::Ref, _, format_args) = expr.kind;
84-
if let ExprKind::Array(elems) = arms[0].body.kind;
85-
if elems.len() == 1;
86-
if let Some(args) = match_function_call(cx, &elems[0], &paths::FMT_ARGUMENTV1_NEW);
87-
// matches `core::fmt::Display::fmt`
88-
if args.len() == 2;
89-
if let ExprKind::Path(ref qpath) = args[1].kind;
90-
if let Some(did) = cx.qpath_res(qpath, args[1].hir_id).opt_def_id();
91-
if match_def_path(cx, did, &paths::DISPLAY_FMT_METHOD);
92-
// check `(arg0,)` in match block
93-
if let PatKind::Tuple(pats, None) = arms[0].pat.kind;
94-
if pats.len() == 1;
95-
then {
96-
let ty = cx.typeck_results().pat_ty(pats[0]).peel_refs();
97-
if *ty.kind() != rustc_middle::ty::Str && !is_type_diagnostic_item(cx, ty, sym::string_type) {
98-
return None;
99-
}
100-
if let ExprKind::Lit(ref lit) = format_args.kind {
101-
if let LitKind::Str(ref s, _) = lit.node {
102-
return Some(format!("{:?}.to_string()", s.as_str()));
51+
let mut applicability = Applicability::MachineApplicable;
52+
if format_args.value_args.is_empty() {
53+
if_chain! {
54+
if let [e] = &*format_args.format_string_parts;
55+
if let ExprKind::Lit(lit) = &e.kind;
56+
if let Some(s_src) = snippet_opt(cx, lit.span);
57+
then {
58+
// Simulate macro expansion, converting {{ and }} to { and }.
59+
let s_expand = s_src.replace("{{", "{").replace("}}", "}");
60+
let sugg = format!("{}.to_string()", s_expand);
61+
span_useless_format(cx, call_site, sugg, applicability);
10362
}
104-
} else {
105-
let sugg = Sugg::hir(cx, format_args, "<arg>");
106-
if let ExprKind::MethodCall(path, _, _, _) = format_args.kind {
107-
if path.ident.name == sym!(to_string) {
108-
return Some(format!("{}", sugg));
109-
}
110-
} else if let ExprKind::Binary(..) = format_args.kind {
111-
return Some(format!("{}", sugg));
63+
}
64+
} else if let [value] = *format_args.value_args {
65+
if_chain! {
66+
if format_args.format_string_symbols == [kw::Empty];
67+
if match cx.typeck_results().expr_ty(value).peel_refs().kind() {
68+
ty::Adt(adt, _) => cx.tcx.is_diagnostic_item(sym::string_type, adt.did),
69+
ty::Str => true,
70+
_ => false,
71+
};
72+
if format_args.args.iter().all(|e| is_display_arg(e));
73+
if format_args.fmt_expr.map_or(true, |e| check_unformatted(e));
74+
then {
75+
let is_new_string = match value.kind {
76+
ExprKind::Binary(..) => true,
77+
ExprKind::MethodCall(path, ..) => path.ident.name.as_str() == "to_string",
78+
_ => false,
79+
};
80+
let sugg = if is_new_string {
81+
snippet_with_applicability(cx, value.span, "..", &mut applicability).into_owned()
82+
} else {
83+
let sugg = Sugg::hir_with_applicability(cx, value, "<arg>", &mut applicability);
84+
format!("{}.to_string()", sugg.maybe_par())
85+
};
86+
span_useless_format(cx, call_site, sugg, applicability);
11287
}
113-
return Some(format!("{}.to_string()", sugg.maybe_par()));
11488
}
115-
}
89+
};
11690
}
117-
None
11891
}
11992

120-
fn on_new_v1<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) -> Option<String> {
121-
if_chain! {
122-
if let Some(args) = match_function_call(cx, expr, &paths::FMT_ARGUMENTS_NEW_V1);
123-
if args.len() == 2;
124-
// Argument 1 in `new_v1()`
125-
if let ExprKind::AddrOf(BorrowKind::Ref, _, arr) = args[0].kind;
126-
if let ExprKind::Array(pieces) = arr.kind;
127-
if pieces.len() == 1;
128-
if let ExprKind::Lit(ref lit) = pieces[0].kind;
129-
if let LitKind::Str(ref s, _) = lit.node;
130-
// Argument 2 in `new_v1()`
131-
if let ExprKind::AddrOf(BorrowKind::Ref, _, arg1) = args[1].kind;
132-
if let ExprKind::Match(matchee, arms, MatchSource::Normal) = arg1.kind;
133-
if arms.len() == 1;
134-
if let ExprKind::Tup(tup) = matchee.kind;
135-
then {
136-
// `format!("foo")` expansion contains `match () { () => [], }`
137-
if tup.is_empty() {
138-
if let Some(s_src) = snippet_opt(cx, lit.span) {
139-
// Simulate macro expansion, converting {{ and }} to { and }.
140-
let s_expand = s_src.replace("{{", "{").replace("}}", "}");
141-
return Some(format!("{}.to_string()", s_expand));
142-
}
143-
} else if s.as_str().is_empty() {
144-
return on_argumentv1_new(cx, &tup[0], arms);
145-
}
146-
}
93+
fn span_useless_format(cx: &LateContext<'_>, span: Span, mut sugg: String, mut applicability: Applicability) {
94+
// The callsite span contains the statement semicolon for some reason.
95+
if snippet_with_applicability(cx, span, "..", &mut applicability).ends_with(';') {
96+
sugg.push(';');
14797
}
148-
None
98+
99+
span_lint_and_sugg(
100+
cx,
101+
USELESS_FORMAT,
102+
span,
103+
"useless use of `format!`",
104+
"consider using `.to_string()`",
105+
sugg,
106+
applicability,
107+
);
149108
}
150109

151-
fn on_new_v1_fmt<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) -> Option<String> {
110+
fn is_display_arg(expr: &Expr<'_>) -> bool {
152111
if_chain! {
153-
if let Some(args) = match_function_call(cx, expr, &paths::FMT_ARGUMENTS_NEW_V1_FORMATTED);
154-
if args.len() == 3;
155-
if check_unformatted(&args[2]);
156-
// Argument 1 in `new_v1_formatted()`
157-
if let ExprKind::AddrOf(BorrowKind::Ref, _, arr) = args[0].kind;
158-
if let ExprKind::Array(pieces) = arr.kind;
159-
if pieces.len() == 1;
160-
if let ExprKind::Lit(ref lit) = pieces[0].kind;
161-
if let LitKind::Str(symbol, _) = lit.node;
162-
if symbol == kw::Empty;
163-
// Argument 2 in `new_v1_formatted()`
164-
if let ExprKind::AddrOf(BorrowKind::Ref, _, arg1) = args[1].kind;
165-
if let ExprKind::Match(matchee, arms, MatchSource::Normal) = arg1.kind;
166-
if arms.len() == 1;
167-
if let ExprKind::Tup(tup) = matchee.kind;
168-
then {
169-
return on_argumentv1_new(cx, &tup[0], arms);
170-
}
112+
if let ExprKind::Call(_, [_, fmt]) = expr.kind;
113+
if let ExprKind::Path(QPath::Resolved(_, path)) = fmt.kind;
114+
if let [.., t, _] = path.segments;
115+
if t.ident.name.as_str() == "Display";
116+
then { true } else { false }
171117
}
172-
None
173118
}
174119

175120
/// Checks if the expression matches
@@ -186,10 +131,9 @@ fn on_new_v1_fmt<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) -> Option<S
186131
fn check_unformatted(expr: &Expr<'_>) -> bool {
187132
if_chain! {
188133
if let ExprKind::AddrOf(BorrowKind::Ref, _, expr) = expr.kind;
189-
if let ExprKind::Array(exprs) = expr.kind;
190-
if exprs.len() == 1;
134+
if let ExprKind::Array([expr]) = expr.kind;
191135
// struct `core::fmt::rt::v1::Argument`
192-
if let ExprKind::Struct(_, fields, _) = exprs[0].kind;
136+
if let ExprKind::Struct(_, fields, _) = expr.kind;
193137
if let Some(format_field) = fields.iter().find(|f| f.ident.name == sym::format);
194138
// struct `core::fmt::rt::v1::FormatSpec`
195139
if let ExprKind::Struct(_, fields, _) = format_field.expr.kind;

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