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Auto merge of #7442 - camsteffen:format-args, r=xFrednet
Refactor `format_args!` expansion parsing Introduces `FormatExpn::parse` and `FormatArgsExpn::parse`. Motivated by #83302, so I only have to change Clippy in one place. Fixed an FP along the way. I also allowed `needless_bool` in macros because I often want to do `if_chain! { .. then { true } else { false } }`. changelog: Fix false positive in `useless_format` when some text is appended or prepended to a single string with some useless formatting params changelog: Allow `needless_bool` in macros
2 parents 94d6be4 + 306f9e8 commit bf4512e

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9 files changed

+238
-265
lines changed

9 files changed

+238
-265
lines changed

‎clippy_lints/src/explicit_write.rs‎

Lines changed: 36 additions & 81 deletions
Original file line numberDiff line numberDiff line change
@@ -1,9 +1,9 @@
1-
use clippy_utils::diagnostics::{span_lint, span_lint_and_sugg};
1+
use clippy_utils::diagnostics::{span_lint_and_help, 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
@@ -70,82 +67,40 @@ 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+
let (used, sugg_mac) = if let Some(macro_name) = calling_macro {
71+
(
72+
format!("{}!({}(), ...)", macro_name, dest_name),
73+
macro_name.replace("write", "print"),
74+
)
75+
} else {
76+
(
77+
format!("{}().write_fmt(...)", dest_name),
78+
"print".into(),
79+
)
80+
};
81+
let msg = format!("use of `{}.unwrap()`", used);
82+
if let [write_output] = *format_args.format_string_symbols {
83+
let mut write_output = write_output.to_string();
7484
if write_output.ends_with('\n') {
7585
write_output.pop();
7686
}
7787

78-
if let Some(macro_name) = calling_macro {
79-
span_lint_and_sugg(
80-
cx,
81-
EXPLICIT_WRITE,
82-
expr.span,
83-
&format!(
84-
"use of `{}!({}(), ...).unwrap()`",
85-
macro_name,
86-
dest_name
87-
),
88-
"try this",
89-
format!("{}{}!(\"{}\")", prefix, macro_name.replace("write", "print"), write_output.escape_default()),
90-
Applicability::MachineApplicable
91-
);
92-
} else {
93-
span_lint_and_sugg(
94-
cx,
95-
EXPLICIT_WRITE,
96-
expr.span,
97-
&format!("use of `{}().write_fmt(...).unwrap()`", dest_name),
98-
"try this",
99-
format!("{}print!(\"{}\")", prefix, write_output.escape_default()),
100-
Applicability::MachineApplicable
101-
);
102-
}
88+
let sugg = format!("{}{}!(\"{}\")", prefix, sugg_mac, write_output.escape_default());
89+
span_lint_and_sugg(
90+
cx,
91+
EXPLICIT_WRITE,
92+
expr.span,
93+
&msg,
94+
"try this",
95+
sugg,
96+
Applicability::MachineApplicable
97+
);
10398
} else {
10499
// We don't have a proper suggestion
105-
if let Some(macro_name) = calling_macro {
106-
span_lint(
107-
cx,
108-
EXPLICIT_WRITE,
109-
expr.span,
110-
&format!(
111-
"use of `{}!({}(), ...).unwrap()`. Consider using `{}{}!` instead",
112-
macro_name,
113-
dest_name,
114-
prefix,
115-
macro_name.replace("write", "print")
116-
)
117-
);
118-
} else {
119-
span_lint(
120-
cx,
121-
EXPLICIT_WRITE,
122-
expr.span,
123-
&format!("use of `{}().write_fmt(...).unwrap()`. Consider using `{}print!` instead", dest_name, prefix),
124-
);
125-
}
100+
let help = format!("consider using `{}{}!` instead", prefix, sugg_mac);
101+
span_lint_and_help(cx, EXPLICIT_WRITE, expr.span, &msg, None, &help);
126102
}
127-
128103
}
129104
}
130105
}
131106
}
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: 69 additions & 123 deletions
Original file line numberDiff line numberDiff line change
@@ -1,17 +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;
12+
use rustc_span::symbol::kw;
13+
use rustc_span::{sym, Span};
1514

1615
declare_clippy_lint! {
1716
/// **What it does:** Checks for the use of `format!("string literal with no
@@ -44,130 +43,78 @@ declare_lint_pass!(UselessFormat => [USELESS_FORMAT]);
4443

4544
impl<'tcx> LateLintPass<'tcx> for UselessFormat {
4645
fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
47-
let span = match is_expn_of(expr.span, "format") {
48-
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,
4948
_ => return,
5049
};
5150

52-
// Operate on the only argument of `alloc::fmt::format`.
53-
if let Some(sugg) = on_new_v1(cx, expr) {
54-
span_useless_format(cx, span, "consider using `.to_string()`", sugg);
55-
} else if let Some(sugg) = on_new_v1_fmt(cx, expr) {
56-
span_useless_format(cx, span, "consider using `.to_string()`", sugg);
57-
}
58-
}
59-
}
60-
61-
fn span_useless_format<T: LintContext>(cx: &T, span: Span, help: &str, mut sugg: String) {
62-
let to_replace = span.source_callsite();
63-
64-
// The callsite span contains the statement semicolon for some reason.
65-
let snippet = snippet(cx, to_replace, "..");
66-
if snippet.ends_with(';') {
67-
sugg.push(';');
68-
}
69-
70-
span_lint_and_then(cx, USELESS_FORMAT, span, "useless use of `format!`", |diag| {
71-
diag.span_suggestion(
72-
to_replace,
73-
help,
74-
sugg,
75-
Applicability::MachineApplicable, // snippet
76-
);
77-
});
78-
}
79-
80-
fn on_argumentv1_new<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>, arms: &'tcx [Arm<'_>]) -> Option<String> {
81-
if_chain! {
82-
if let ExprKind::AddrOf(BorrowKind::Ref, _, format_args) = expr.kind;
83-
if let ExprKind::Array(elems) = arms[0].body.kind;
84-
if elems.len() == 1;
85-
if let Some(args) = match_function_call(cx, &elems[0], &paths::FMT_ARGUMENTV1_NEW);
86-
// matches `core::fmt::Display::fmt`
87-
if args.len() == 2;
88-
if let ExprKind::Path(ref qpath) = args[1].kind;
89-
if let Some(did) = cx.qpath_res(qpath, args[1].hir_id).opt_def_id();
90-
if match_def_path(cx, did, &paths::DISPLAY_FMT_METHOD);
91-
// check `(arg0,)` in match block
92-
if let PatKind::Tuple(pats, None) = arms[0].pat.kind;
93-
if pats.len() == 1;
94-
then {
95-
let ty = cx.typeck_results().pat_ty(pats[0]).peel_refs();
96-
if *ty.kind() != rustc_middle::ty::Str && !is_type_diagnostic_item(cx, ty, sym::string_type) {
97-
return None;
98-
}
99-
if let ExprKind::Lit(ref lit) = format_args.kind {
100-
if let LitKind::Str(ref s, _) = lit.node {
101-
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);
10262
}
103-
} else {
104-
let sugg = Sugg::hir(cx, format_args, "<arg>");
105-
if let ExprKind::MethodCall(path, _, _, _) = format_args.kind {
106-
if path.ident.name == sym!(to_string) {
107-
return Some(format!("{}", sugg));
108-
}
109-
} else if let ExprKind::Binary(..) = format_args.kind {
110-
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);
11187
}
112-
return Some(format!("{}.to_string()", sugg.maybe_par()));
11388
}
114-
}
89+
};
11590
}
116-
None
11791
}
11892

119-
fn on_new_v1<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) -> Option<String> {
120-
if_chain! {
121-
if let Some(args) = match_function_call(cx, expr, &paths::FMT_ARGUMENTS_NEW_V1);
122-
if args.len() == 2;
123-
// Argument 1 in `new_v1()`
124-
if let ExprKind::AddrOf(BorrowKind::Ref, _, arr) = args[0].kind;
125-
if let ExprKind::Array(pieces) = arr.kind;
126-
if pieces.len() == 1;
127-
if let ExprKind::Lit(ref lit) = pieces[0].kind;
128-
if let LitKind::Str(ref s, _) = lit.node;
129-
// Argument 2 in `new_v1()`
130-
if let ExprKind::AddrOf(BorrowKind::Ref, _, arg1) = args[1].kind;
131-
if let ExprKind::Match(matchee, arms, MatchSource::Normal) = arg1.kind;
132-
if arms.len() == 1;
133-
if let ExprKind::Tup(tup) = matchee.kind;
134-
then {
135-
// `format!("foo")` expansion contains `match () { () => [], }`
136-
if tup.is_empty() {
137-
if let Some(s_src) = snippet_opt(cx, lit.span) {
138-
// Simulate macro expansion, converting {{ and }} to { and }.
139-
let s_expand = s_src.replace("{{", "{").replace("}}", "}");
140-
return Some(format!("{}.to_string()", s_expand));
141-
}
142-
} else if s.as_str().is_empty() {
143-
return on_argumentv1_new(cx, &tup[0], arms);
144-
}
145-
}
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(';');
14697
}
147-
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+
);
148108
}
149109

150-
fn on_new_v1_fmt<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) -> Option<String> {
110+
fn is_display_arg(expr: &Expr<'_>) -> bool {
151111
if_chain! {
152-
if let Some(args) = match_function_call(cx, expr, &paths::FMT_ARGUMENTS_NEW_V1_FORMATTED);
153-
if args.len() == 3;
154-
if check_unformatted(&args[2]);
155-
// Argument 1 in `new_v1_formatted()`
156-
if let ExprKind::AddrOf(BorrowKind::Ref, _, arr) = args[0].kind;
157-
if let ExprKind::Array(pieces) = arr.kind;
158-
if pieces.len() == 1;
159-
if let ExprKind::Lit(ref lit) = pieces[0].kind;
160-
if let LitKind::Str(..) = lit.node;
161-
// Argument 2 in `new_v1_formatted()`
162-
if let ExprKind::AddrOf(BorrowKind::Ref, _, arg1) = args[1].kind;
163-
if let ExprKind::Match(matchee, arms, MatchSource::Normal) = arg1.kind;
164-
if arms.len() == 1;
165-
if let ExprKind::Tup(tup) = matchee.kind;
166-
then {
167-
return on_argumentv1_new(cx, &tup[0], arms);
168-
}
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 }
169117
}
170-
None
171118
}
172119

173120
/// Checks if the expression matches
@@ -184,10 +131,9 @@ fn on_new_v1_fmt<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) -> Option<S
184131
fn check_unformatted(expr: &Expr<'_>) -> bool {
185132
if_chain! {
186133
if let ExprKind::AddrOf(BorrowKind::Ref, _, expr) = expr.kind;
187-
if let ExprKind::Array(exprs) = expr.kind;
188-
if exprs.len() == 1;
134+
if let ExprKind::Array([expr]) = expr.kind;
189135
// struct `core::fmt::rt::v1::Argument`
190-
if let ExprKind::Struct(_, fields, _) = exprs[0].kind;
136+
if let ExprKind::Struct(_, fields, _) = expr.kind;
191137
if let Some(format_field) = fields.iter().find(|f| f.ident.name == sym::format);
192138
// struct `core::fmt::rt::v1::FormatSpec`
193139
if let ExprKind::Struct(_, fields, _) = format_field.expr.kind;

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