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Minor refactor format-args

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* Move all linting logic into a single format implementations struct

This should help with the future format-args improvements.
This commit is contained in:
Yuri Astrakhan 2024-02-12 13:20:52 -05:00
parent b0e7640fd7
commit 7c8690ca97
1 changed files with 256 additions and 247 deletions
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503
clippy_lints/src/format_args.rs
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@ -4,7 +4,7 @@ use clippy_utils::diagnostics::{span_lint_and_sugg, span_lint_and_then};
use clippy_utils::is_diag_trait_item;
use clippy_utils::macros::{
find_format_arg_expr, find_format_args, format_arg_removal_span, format_placeholder_format_span, is_assert_macro,
is_format_macro, is_panic, root_macro_call, root_macro_call_first_node, FormatParamUsage,
is_format_macro, is_panic, root_macro_call, root_macro_call_first_node, FormatParamUsage, MacroCall,
};
use clippy_utils::source::snippet_opt;
use clippy_utils::ty::{implements_trait, is_type_lang_item};
@ -20,7 +20,6 @@ use rustc_lint::{LateContext, LateLintPass, LintContext};
use rustc_middle::ty::adjustment::{Adjust, Adjustment};
use rustc_middle::ty::Ty;
use rustc_session::impl_lint_pass;
use rustc_span::def_id::DefId;
use rustc_span::edition::Edition::Edition2021;
use rustc_span::{sym, Span, Symbol};
@ -189,32 +188,18 @@ impl<'tcx> LateLintPass<'tcx> for FormatArgs {
&& is_format_macro(cx, macro_call.def_id)
&& let Some(format_args) = find_format_args(cx, expr, macro_call.expn)
{
for piece in &format_args.template {
if let FormatArgsPiece::Placeholder(placeholder) = piece
&& let Ok(index) = placeholder.argument.index
&& let Some(arg) = format_args.arguments.all_args().get(index)
{
let arg_expr = find_format_arg_expr(expr, arg);
let linter = FormatArgsExpr {
cx,
expr,
macro_call,
format_args: &format_args,
ignore_mixed: self.ignore_mixed,
};
check_unused_format_specifier(cx, placeholder, arg_expr);
if placeholder.format_trait != FormatTrait::Display
|| placeholder.format_options != FormatOptions::default()
|| is_aliased(&format_args, index)
{
continue;
}
if let Ok(arg_hir_expr) = arg_expr {
let name = cx.tcx.item_name(macro_call.def_id);
check_format_in_format_args(cx, macro_call.span, name, arg_hir_expr);
check_to_string_in_format_args(cx, name, arg_hir_expr);
}
}
}
linter.check_templates();
if self.msrv.meets(msrvs::FORMAT_ARGS_CAPTURE) {
check_uninlined_args(cx, &format_args, macro_call.span, macro_call.def_id, self.ignore_mixed);
linter.check_uninlined_args();
}
}
}
@ -222,255 +207,279 @@ impl<'tcx> LateLintPass<'tcx> for FormatArgs {
extract_msrv_attr!(LateContext);
}
fn check_unused_format_specifier(
cx: &LateContext<'_>,
placeholder: &FormatPlaceholder,
arg_expr: Result<&Expr<'_>, &rustc_ast::Expr>,
) {
let ty_or_ast_expr = arg_expr.map(|expr| cx.typeck_results().expr_ty(expr).peel_refs());
struct FormatArgsExpr<'a, 'tcx> {
cx: &'a LateContext<'tcx>,
expr: &'tcx Expr<'tcx>,
macro_call: MacroCall,
format_args: &'a rustc_ast::FormatArgs,
ignore_mixed: bool,
}
let is_format_args = match ty_or_ast_expr {
Ok(ty) => is_type_lang_item(cx, ty, LangItem::FormatArguments),
Err(expr) => matches!(expr.peel_parens_and_refs().kind, rustc_ast::ExprKind::FormatArgs(_)),
};
impl<'a, 'tcx> FormatArgsExpr<'a, 'tcx> {
fn check_templates(&self) {
for piece in &self.format_args.template {
if let FormatArgsPiece::Placeholder(placeholder) = piece
&& let Ok(index) = placeholder.argument.index
&& let Some(arg) = self.format_args.arguments.all_args().get(index)
{
let arg_expr = find_format_arg_expr(self.expr, arg);
let options = &placeholder.format_options;
self.check_unused_format_specifier(placeholder, arg_expr);
let arg_span = match arg_expr {
Ok(expr) => expr.span,
Err(expr) => expr.span,
};
if let Ok(arg_expr) = arg_expr
&& placeholder.format_trait == FormatTrait::Display
&& placeholder.format_options == FormatOptions::default()
&& !self.is_aliased(index)
{
let name = self.cx.tcx.item_name(self.macro_call.def_id);
self.check_format_in_format_args(name, arg_expr);
self.check_to_string_in_format_args(name, arg_expr);
}
}
}
}
if let Some(placeholder_span) = placeholder.span
&& is_format_args
&& *options != FormatOptions::default()
{
span_lint_and_then(
cx,
UNUSED_FORMAT_SPECS,
placeholder_span,
"format specifiers have no effect on `format_args!()`",
|diag| {
let mut suggest_format = |spec| {
let message = format!("for the {spec} to apply consider using `format!()`");
fn check_unused_format_specifier(
&self,
placeholder: &FormatPlaceholder,
arg_expr: Result<&Expr<'_>, &rustc_ast::Expr>,
) {
let ty_or_ast_expr = arg_expr.map(|expr| self.cx.typeck_results().expr_ty(expr).peel_refs());
if let Some(mac_call) = root_macro_call(arg_span)
&& cx.tcx.is_diagnostic_item(sym::format_args_macro, mac_call.def_id)
{
diag.span_suggestion(
cx.sess().source_map().span_until_char(mac_call.span, '!'),
message,
"format",
let is_format_args = match ty_or_ast_expr {
Ok(ty) => is_type_lang_item(self.cx, ty, LangItem::FormatArguments),
Err(expr) => matches!(expr.peel_parens_and_refs().kind, rustc_ast::ExprKind::FormatArgs(_)),
};
let options = &placeholder.format_options;
let arg_span = match arg_expr {
Ok(expr) => expr.span,
Err(expr) => expr.span,
};
if let Some(placeholder_span) = placeholder.span
&& is_format_args
&& *options != FormatOptions::default()
{
span_lint_and_then(
self.cx,
UNUSED_FORMAT_SPECS,
placeholder_span,
"format specifiers have no effect on `format_args!()`",
|diag| {
let mut suggest_format = |spec| {
let message = format!("for the {spec} to apply consider using `format!()`");
if let Some(mac_call) = root_macro_call(arg_span)
&& self.cx.tcx.is_diagnostic_item(sym::format_args_macro, mac_call.def_id)
{
diag.span_suggestion(
self.cx.sess().source_map().span_until_char(mac_call.span, '!'),
message,
"format",
Applicability::MaybeIncorrect,
);
} else {
diag.help(message);
}
};
if options.width.is_some() {
suggest_format("width");
}
if options.precision.is_some() {
suggest_format("precision");
}
if let Some(format_span) = format_placeholder_format_span(placeholder) {
diag.span_suggestion_verbose(
format_span,
"if the current behavior is intentional, remove the format specifiers",
"",
Applicability::MaybeIncorrect,
);
} else {
diag.help(message);
}
};
},
);
}
}
if options.width.is_some() {
suggest_format("width");
}
fn check_uninlined_args(&self) {
if self.format_args.span.from_expansion() {
return;
}
if self.macro_call.span.edition() < Edition2021
&& (is_panic(self.cx, self.macro_call.def_id) || is_assert_macro(self.cx, self.macro_call.def_id))
{
// panic!, assert!, and debug_assert! before 2021 edition considers a single string argument as
// non-format
return;
}
if options.precision.is_some() {
suggest_format("precision");
}
let mut fixes = Vec::new();
// If any of the arguments are referenced by an index number,
// and that argument is not a simple variable and cannot be inlined,
// we cannot remove any other arguments in the format string,
// because the index numbers might be wrong after inlining.
// Example of an un-inlinable format: print!("{}{1}", foo, 2)
for (pos, usage) in self.format_arg_positions() {
if !self.check_one_arg(pos, usage, &mut fixes) {
return;
}
}
if let Some(format_span) = format_placeholder_format_span(placeholder) {
diag.span_suggestion_verbose(
format_span,
"if the current behavior is intentional, remove the format specifiers",
"",
Applicability::MaybeIncorrect,
);
}
if fixes.is_empty() {
return;
}
// multiline span display suggestion is sometimes broken: https://github.com/rust-lang/rust/pull/102729#discussion_r988704308
// in those cases, make the code suggestion hidden
let multiline_fix = fixes
.iter()
.any(|(span, _)| self.cx.sess().source_map().is_multiline(*span));
// Suggest removing each argument only once, for example in `format!("{0} {0}", arg)`.
fixes.sort_unstable_by_key(|(span, _)| *span);
fixes.dedup_by_key(|(span, _)| *span);
span_lint_and_then(
self.cx,
UNINLINED_FORMAT_ARGS,
self.macro_call.span,
"variables can be used directly in the `format!` string",
|diag| {
diag.multipart_suggestion_with_style(
"change this to",
fixes,
Applicability::MachineApplicable,
if multiline_fix { CompletelyHidden } else { ShowCode },
);
},
);
}
}
fn check_uninlined_args(
cx: &LateContext<'_>,
args: &rustc_ast::FormatArgs,
call_site: Span,
def_id: DefId,
ignore_mixed: bool,
) {
if args.span.from_expansion() {
return;
}
if call_site.edition() < Edition2021 && (is_panic(cx, def_id) || is_assert_macro(cx, def_id)) {
// panic!, assert!, and debug_assert! before 2021 edition considers a single string argument as
// non-format
return;
fn check_one_arg(&self, pos: &FormatArgPosition, usage: FormatParamUsage, fixes: &mut Vec<(Span, String)>) -> bool {
let index = pos.index.unwrap();
let arg = &self.format_args.arguments.all_args()[index];
if !matches!(arg.kind, FormatArgumentKind::Captured(_))
&& let rustc_ast::ExprKind::Path(None, path) = &arg.expr.kind
&& let [segment] = path.segments.as_slice()
&& segment.args.is_none()
&& let Some(arg_span) = format_arg_removal_span(self.format_args, index)
&& let Some(pos_span) = pos.span
{
let replacement = match usage {
FormatParamUsage::Argument => segment.ident.name.to_string(),
FormatParamUsage::Width => format!("{}$", segment.ident.name),
FormatParamUsage::Precision => format!(".{}$", segment.ident.name),
};
fixes.push((pos_span, replacement));
fixes.push((arg_span, String::new()));
true // successful inlining, continue checking
} else {
// Do not continue inlining (return false) in case
// * if we can't inline a numbered argument, e.g. `print!("{0} ...", foo.bar, ...)`
// * if allow_mixed_uninlined_format_args is false and this arg hasn't been inlined already
pos.kind != FormatArgPositionKind::Number
&& (!self.ignore_mixed || matches!(arg.kind, FormatArgumentKind::Captured(_)))
}
}
let mut fixes = Vec::new();
// If any of the arguments are referenced by an index number,
// and that argument is not a simple variable and cannot be inlined,
// we cannot remove any other arguments in the format string,
// because the index numbers might be wrong after inlining.
// Example of an un-inlinable format: print!("{}{1}", foo, 2)
for (pos, usage) in format_arg_positions(args) {
if !check_one_arg(args, pos, usage, &mut fixes, ignore_mixed) {
fn check_format_in_format_args(&self, name: Symbol, arg: &Expr<'_>) {
let expn_data = arg.span.ctxt().outer_expn_data();
if expn_data.call_site.from_expansion() {
return;
}
let Some(mac_id) = expn_data.macro_def_id else { return };
if !self.cx.tcx.is_diagnostic_item(sym::format_macro, mac_id) {
return;
}
span_lint_and_then(
self.cx,
FORMAT_IN_FORMAT_ARGS,
self.macro_call.span,
&format!("`format!` in `{name}!` args"),
|diag| {
diag.help(format!(
"combine the `format!(..)` arguments with the outer `{name}!(..)` call"
));
diag.help("or consider changing `format!` to `format_args!`");
},
);
}
if fixes.is_empty() {
return;
}
// multiline span display suggestion is sometimes broken: https://github.com/rust-lang/rust/pull/102729#discussion_r988704308
// in those cases, make the code suggestion hidden
let multiline_fix = fixes.iter().any(|(span, _)| cx.sess().source_map().is_multiline(*span));
// Suggest removing each argument only once, for example in `format!("{0} {0}", arg)`.
fixes.sort_unstable_by_key(|(span, _)| *span);
fixes.dedup_by_key(|(span, _)| *span);
span_lint_and_then(
cx,
UNINLINED_FORMAT_ARGS,
call_site,
"variables can be used directly in the `format!` string",
|diag| {
diag.multipart_suggestion_with_style(
"change this to",
fixes,
Applicability::MachineApplicable,
if multiline_fix { CompletelyHidden } else { ShowCode },
);
},
);
}
fn check_one_arg(
args: &rustc_ast::FormatArgs,
pos: &FormatArgPosition,
usage: FormatParamUsage,
fixes: &mut Vec<(Span, String)>,
ignore_mixed: bool,
) -> bool {
let index = pos.index.unwrap();
let arg = &args.arguments.all_args()[index];
if !matches!(arg.kind, FormatArgumentKind::Captured(_))
&& let rustc_ast::ExprKind::Path(None, path) = &arg.expr.kind
&& let [segment] = path.segments.as_slice()
&& segment.args.is_none()
&& let Some(arg_span) = format_arg_removal_span(args, index)
&& let Some(pos_span) = pos.span
{
let replacement = match usage {
FormatParamUsage::Argument => segment.ident.name.to_string(),
FormatParamUsage::Width => format!("{}$", segment.ident.name),
FormatParamUsage::Precision => format!(".{}$", segment.ident.name),
};
fixes.push((pos_span, replacement));
fixes.push((arg_span, String::new()));
true // successful inlining, continue checking
} else {
// Do not continue inlining (return false) in case
// * if we can't inline a numbered argument, e.g. `print!("{0} ...", foo.bar, ...)`
// * if allow_mixed_uninlined_format_args is false and this arg hasn't been inlined already
pos.kind != FormatArgPositionKind::Number
&& (!ignore_mixed || matches!(arg.kind, FormatArgumentKind::Captured(_)))
}
}
fn check_format_in_format_args(cx: &LateContext<'_>, call_site: Span, name: Symbol, arg: &Expr<'_>) {
let expn_data = arg.span.ctxt().outer_expn_data();
if expn_data.call_site.from_expansion() {
return;
}
let Some(mac_id) = expn_data.macro_def_id else { return };
if !cx.tcx.is_diagnostic_item(sym::format_macro, mac_id) {
return;
}
span_lint_and_then(
cx,
FORMAT_IN_FORMAT_ARGS,
call_site,
&format!("`format!` in `{name}!` args"),
|diag| {
diag.help(format!(
"combine the `format!(..)` arguments with the outer `{name}!(..)` call"
));
diag.help("or consider changing `format!` to `format_args!`");
},
);
}
fn check_to_string_in_format_args(cx: &LateContext<'_>, name: Symbol, value: &Expr<'_>) {
if !value.span.from_expansion()
&& let ExprKind::MethodCall(_, receiver, [], to_string_span) = value.kind
&& let Some(method_def_id) = cx.typeck_results().type_dependent_def_id(value.hir_id)
&& is_diag_trait_item(cx, method_def_id, sym::ToString)
&& let receiver_ty = cx.typeck_results().expr_ty(receiver)
&& let Some(display_trait_id) = cx.tcx.get_diagnostic_item(sym::Display)
&& let (n_needed_derefs, target) =
count_needed_derefs(receiver_ty, cx.typeck_results().expr_adjustments(receiver).iter())
&& implements_trait(cx, target, display_trait_id, &[])
&& let Some(sized_trait_id) = cx.tcx.lang_items().sized_trait()
&& let Some(receiver_snippet) = snippet_opt(cx, receiver.span)
{
let needs_ref = !implements_trait(cx, receiver_ty, sized_trait_id, &[]);
if n_needed_derefs == 0 && !needs_ref {
span_lint_and_sugg(
cx,
TO_STRING_IN_FORMAT_ARGS,
to_string_span.with_lo(receiver.span.hi()),
&format!("`to_string` applied to a type that implements `Display` in `{name}!` args"),
"remove this",
String::new(),
Applicability::MachineApplicable,
);
} else {
span_lint_and_sugg(
cx,
TO_STRING_IN_FORMAT_ARGS,
value.span,
&format!("`to_string` applied to a type that implements `Display` in `{name}!` args"),
"use this",
format!(
"{}{:*>n_needed_derefs$}{receiver_snippet}",
if needs_ref { "&" } else { "" },
""
),
Applicability::MachineApplicable,
);
fn check_to_string_in_format_args(&self, name: Symbol, value: &Expr<'_>) {
let cx = self.cx;
if !value.span.from_expansion()
&& let ExprKind::MethodCall(_, receiver, [], to_string_span) = value.kind
&& let Some(method_def_id) = cx.typeck_results().type_dependent_def_id(value.hir_id)
&& is_diag_trait_item(cx, method_def_id, sym::ToString)
&& let receiver_ty = cx.typeck_results().expr_ty(receiver)
&& let Some(display_trait_id) = cx.tcx.get_diagnostic_item(sym::Display)
&& let (n_needed_derefs, target) =
count_needed_derefs(receiver_ty, cx.typeck_results().expr_adjustments(receiver).iter())
&& implements_trait(cx, target, display_trait_id, &[])
&& let Some(sized_trait_id) = cx.tcx.lang_items().sized_trait()
&& let Some(receiver_snippet) = snippet_opt(cx, receiver.span)
{
let needs_ref = !implements_trait(cx, receiver_ty, sized_trait_id, &[]);
if n_needed_derefs == 0 && !needs_ref {
span_lint_and_sugg(
cx,
TO_STRING_IN_FORMAT_ARGS,
to_string_span.with_lo(receiver.span.hi()),
&format!("`to_string` applied to a type that implements `Display` in `{name}!` args"),
"remove this",
String::new(),
Applicability::MachineApplicable,
);
} else {
span_lint_and_sugg(
cx,
TO_STRING_IN_FORMAT_ARGS,
value.span,
&format!("`to_string` applied to a type that implements `Display` in `{name}!` args"),
"use this",
format!(
"{}{:*>n_needed_derefs$}{receiver_snippet}",
if needs_ref { "&" } else { "" },
""
),
Applicability::MachineApplicable,
);
}
}
}
}
fn format_arg_positions(
format_args: &rustc_ast::FormatArgs,
) -> impl Iterator<Item = (&FormatArgPosition, FormatParamUsage)> {
format_args.template.iter().flat_map(|piece| match piece {
FormatArgsPiece::Placeholder(placeholder) => {
let mut positions = ArrayVec::<_, 3>::new();
fn format_arg_positions(&self) -> impl Iterator<Item = (&FormatArgPosition, FormatParamUsage)> {
self.format_args.template.iter().flat_map(|piece| match piece {
FormatArgsPiece::Placeholder(placeholder) => {
let mut positions = ArrayVec::<_, 3>::new();
positions.push((&placeholder.argument, FormatParamUsage::Argument));
if let Some(FormatCount::Argument(position)) = &placeholder.format_options.width {
positions.push((position, FormatParamUsage::Width));
}
if let Some(FormatCount::Argument(position)) = &placeholder.format_options.precision {
positions.push((position, FormatParamUsage::Precision));
}
positions.push((&placeholder.argument, FormatParamUsage::Argument));
if let Some(FormatCount::Argument(position)) = &placeholder.format_options.width {
positions.push((position, FormatParamUsage::Width));
}
if let Some(FormatCount::Argument(position)) = &placeholder.format_options.precision {
positions.push((position, FormatParamUsage::Precision));
}
positions
},
FormatArgsPiece::Literal(_) => ArrayVec::new(),
})
}
positions
},
FormatArgsPiece::Literal(_) => ArrayVec::new(),
})
}
/// Returns true if the format argument at `index` is referred to by multiple format params
fn is_aliased(format_args: &rustc_ast::FormatArgs, index: usize) -> bool {
format_arg_positions(format_args)
.filter(|(position, _)| position.index == Ok(index))
.at_most_one()
.is_err()
/// Returns true if the format argument at `index` is referred to by multiple format params
fn is_aliased(&self, index: usize) -> bool {
self.format_arg_positions()
.filter(|(position, _)| position.index == Ok(index))
.at_most_one()
.is_err()
}
}
fn count_needed_derefs<'tcx, I>(mut ty: Ty<'tcx>, mut iter: I) -> (usize, Ty<'tcx>)