rust/clippy_utils/src/macros.rs

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#![allow(clippy::similar_names)] // `expr` and `expn`
use crate::is_path_diagnostic_item;
use crate::source::snippet_opt;
use crate::visitors::expr_visitor_no_bodies;
use arrayvec::ArrayVec;
use itertools::{izip, Either, Itertools};
use rustc_ast::ast::LitKind;
use rustc_hir::intravisit::{walk_expr, Visitor};
use rustc_hir::{self as hir, Expr, ExprField, ExprKind, HirId, Node, QPath};
use rustc_lexer::unescape::unescape_literal;
use rustc_lexer::{tokenize, unescape, LiteralKind, TokenKind};
use rustc_lint::LateContext;
use rustc_parse_format::{self as rpf, Alignment};
use rustc_span::def_id::DefId;
use rustc_span::hygiene::{self, MacroKind, SyntaxContext};
use rustc_span::{sym, BytePos, ExpnData, ExpnId, ExpnKind, Pos, Span, SpanData, Symbol};
use std::ops::ControlFlow;
const FORMAT_MACRO_DIAG_ITEMS: &[Symbol] = &[
sym::assert_eq_macro,
sym::assert_macro,
sym::assert_ne_macro,
sym::debug_assert_eq_macro,
sym::debug_assert_macro,
sym::debug_assert_ne_macro,
sym::eprint_macro,
sym::eprintln_macro,
sym::format_args_macro,
sym::format_macro,
sym::print_macro,
sym::println_macro,
sym::std_panic_macro,
sym::write_macro,
sym::writeln_macro,
];
/// Returns true if a given Macro `DefId` is a format macro (e.g. `println!`)
pub fn is_format_macro(cx: &LateContext<'_>, macro_def_id: DefId) -> bool {
if let Some(name) = cx.tcx.get_diagnostic_name(macro_def_id) {
FORMAT_MACRO_DIAG_ITEMS.contains(&name)
} else {
false
}
}
/// A macro call, like `vec![1, 2, 3]`.
///
/// Use `tcx.item_name(macro_call.def_id)` to get the macro name.
/// Even better is to check if it is a diagnostic item.
///
/// This structure is similar to `ExpnData` but it precludes desugaring expansions.
#[derive(Debug)]
pub struct MacroCall {
/// Macro `DefId`
pub def_id: DefId,
/// Kind of macro
pub kind: MacroKind,
/// The expansion produced by the macro call
pub expn: ExpnId,
/// Span of the macro call site
pub span: Span,
}
impl MacroCall {
pub fn is_local(&self) -> bool {
span_is_local(self.span)
}
}
/// Returns an iterator of expansions that created the given span
pub fn expn_backtrace(mut span: Span) -> impl Iterator<Item = (ExpnId, ExpnData)> {
std::iter::from_fn(move || {
let ctxt = span.ctxt();
if ctxt == SyntaxContext::root() {
return None;
}
let expn = ctxt.outer_expn();
let data = expn.expn_data();
span = data.call_site;
Some((expn, data))
})
}
/// Checks whether the span is from the root expansion or a locally defined macro
pub fn span_is_local(span: Span) -> bool {
!span.from_expansion() || expn_is_local(span.ctxt().outer_expn())
}
/// Checks whether the expansion is the root expansion or a locally defined macro
pub fn expn_is_local(expn: ExpnId) -> bool {
if expn == ExpnId::root() {
return true;
}
let data = expn.expn_data();
let backtrace = expn_backtrace(data.call_site);
std::iter::once((expn, data))
.chain(backtrace)
.find_map(|(_, data)| data.macro_def_id)
.map_or(true, DefId::is_local)
}
/// Returns an iterator of macro expansions that created the given span.
/// Note that desugaring expansions are skipped.
pub fn macro_backtrace(span: Span) -> impl Iterator<Item = MacroCall> {
expn_backtrace(span).filter_map(|(expn, data)| match data {
ExpnData {
kind: ExpnKind::Macro(kind, _),
macro_def_id: Some(def_id),
call_site: span,
..
} => Some(MacroCall {
def_id,
kind,
expn,
span,
}),
_ => None,
})
}
/// If the macro backtrace of `span` has a macro call at the root expansion
/// (i.e. not a nested macro call), returns `Some` with the `MacroCall`
pub fn root_macro_call(span: Span) -> Option<MacroCall> {
macro_backtrace(span).last()
}
/// Like [`root_macro_call`], but only returns `Some` if `node` is the "first node"
/// produced by the macro call, as in [`first_node_in_macro`].
pub fn root_macro_call_first_node(cx: &LateContext<'_>, node: &impl HirNode) -> Option<MacroCall> {
if first_node_in_macro(cx, node) != Some(ExpnId::root()) {
return None;
}
root_macro_call(node.span())
}
/// Like [`macro_backtrace`], but only returns macro calls where `node` is the "first node" of the
/// macro call, as in [`first_node_in_macro`].
pub fn first_node_macro_backtrace(cx: &LateContext<'_>, node: &impl HirNode) -> impl Iterator<Item = MacroCall> {
let span = node.span();
first_node_in_macro(cx, node)
.into_iter()
.flat_map(move |expn| macro_backtrace(span).take_while(move |macro_call| macro_call.expn != expn))
}
/// If `node` is the "first node" in a macro expansion, returns `Some` with the `ExpnId` of the
/// macro call site (i.e. the parent of the macro expansion). This generally means that `node`
/// is the outermost node of an entire macro expansion, but there are some caveats noted below.
/// This is useful for finding macro calls while visiting the HIR without processing the macro call
/// at every node within its expansion.
///
/// If you already have immediate access to the parent node, it is simpler to
/// just check the context of that span directly (e.g. `parent.span.from_expansion()`).
///
/// If a macro call is in statement position, it expands to one or more statements.
/// In that case, each statement *and* their immediate descendants will all yield `Some`
/// with the `ExpnId` of the containing block.
///
/// A node may be the "first node" of multiple macro calls in a macro backtrace.
/// The expansion of the outermost macro call site is returned in such cases.
pub fn first_node_in_macro(cx: &LateContext<'_>, node: &impl HirNode) -> Option<ExpnId> {
// get the macro expansion or return `None` if not found
// `macro_backtrace` importantly ignores desugaring expansions
let expn = macro_backtrace(node.span()).next()?.expn;
// get the parent node, possibly skipping over a statement
// if the parent is not found, it is sensible to return `Some(root)`
let hir = cx.tcx.hir();
let mut parent_iter = hir.parent_iter(node.hir_id());
let (parent_id, _) = match parent_iter.next() {
None => return Some(ExpnId::root()),
Some((_, Node::Stmt(_))) => match parent_iter.next() {
None => return Some(ExpnId::root()),
Some(next) => next,
},
Some(next) => next,
};
// get the macro expansion of the parent node
let parent_span = hir.span(parent_id);
let Some(parent_macro_call) = macro_backtrace(parent_span).next() else {
// the parent node is not in a macro
return Some(ExpnId::root());
};
if parent_macro_call.expn.is_descendant_of(expn) {
// `node` is input to a macro call
return None;
}
Some(parent_macro_call.expn)
}
/* Specific Macro Utils */
/// Is `def_id` of `std::panic`, `core::panic` or any inner implementation macros
pub fn is_panic(cx: &LateContext<'_>, def_id: DefId) -> bool {
let Some(name) = cx.tcx.get_diagnostic_name(def_id) else { return false };
matches!(
name.as_str(),
"core_panic_macro"
| "std_panic_macro"
| "core_panic_2015_macro"
| "std_panic_2015_macro"
| "core_panic_2021_macro"
)
}
pub enum PanicExpn<'a> {
/// No arguments - `panic!()`
Empty,
/// A string literal or any `&str` - `panic!("message")` or `panic!(message)`
Str(&'a Expr<'a>),
/// A single argument that implements `Display` - `panic!("{}", object)`
Display(&'a Expr<'a>),
/// Anything else - `panic!("error {}: {}", a, b)`
Format(FormatArgsExpn<'a>),
}
impl<'a> PanicExpn<'a> {
pub fn parse(cx: &LateContext<'_>, expr: &'a Expr<'a>) -> Option<Self> {
if !macro_backtrace(expr.span).any(|macro_call| is_panic(cx, macro_call.def_id)) {
return None;
}
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let ExprKind::Call(callee, [arg]) = &expr.kind else { return None };
let ExprKind::Path(QPath::Resolved(_, path)) = &callee.kind else { return None };
let result = match path.segments.last().unwrap().ident.as_str() {
"panic" if arg.span.ctxt() == expr.span.ctxt() => Self::Empty,
"panic" | "panic_str" => Self::Str(arg),
"panic_display" => {
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let ExprKind::AddrOf(_, _, e) = &arg.kind else { return None };
Self::Display(e)
},
"panic_fmt" => Self::Format(FormatArgsExpn::parse(cx, arg)?),
_ => return None,
};
Some(result)
}
}
/// Finds the arguments of an `assert!` or `debug_assert!` macro call within the macro expansion
pub fn find_assert_args<'a>(
cx: &LateContext<'_>,
expr: &'a Expr<'a>,
expn: ExpnId,
) -> Option<(&'a Expr<'a>, PanicExpn<'a>)> {
find_assert_args_inner(cx, expr, expn).map(|([e], p)| (e, p))
}
/// Finds the arguments of an `assert_eq!` or `debug_assert_eq!` macro call within the macro
/// expansion
pub fn find_assert_eq_args<'a>(
cx: &LateContext<'_>,
expr: &'a Expr<'a>,
expn: ExpnId,
) -> Option<(&'a Expr<'a>, &'a Expr<'a>, PanicExpn<'a>)> {
find_assert_args_inner(cx, expr, expn).map(|([a, b], p)| (a, b, p))
}
fn find_assert_args_inner<'a, const N: usize>(
cx: &LateContext<'_>,
expr: &'a Expr<'a>,
expn: ExpnId,
) -> Option<([&'a Expr<'a>; N], PanicExpn<'a>)> {
let macro_id = expn.expn_data().macro_def_id?;
let (expr, expn) = match cx.tcx.item_name(macro_id).as_str().strip_prefix("debug_") {
None => (expr, expn),
Some(inner_name) => find_assert_within_debug_assert(cx, expr, expn, Symbol::intern(inner_name))?,
};
let mut args = ArrayVec::new();
let mut panic_expn = None;
expr_visitor_no_bodies(|e| {
if args.is_full() {
if panic_expn.is_none() && e.span.ctxt() != expr.span.ctxt() {
panic_expn = PanicExpn::parse(cx, e);
}
panic_expn.is_none()
} else if is_assert_arg(cx, e, expn) {
args.push(e);
false
} else {
true
}
})
.visit_expr(expr);
let args = args.into_inner().ok()?;
// if no `panic!(..)` is found, use `PanicExpn::Empty`
// to indicate that the default assertion message is used
let panic_expn = panic_expn.unwrap_or(PanicExpn::Empty);
Some((args, panic_expn))
}
fn find_assert_within_debug_assert<'a>(
cx: &LateContext<'_>,
expr: &'a Expr<'a>,
expn: ExpnId,
assert_name: Symbol,
) -> Option<(&'a Expr<'a>, ExpnId)> {
let mut found = None;
expr_visitor_no_bodies(|e| {
if found.is_some() || !e.span.from_expansion() {
return false;
}
let e_expn = e.span.ctxt().outer_expn();
if e_expn == expn {
return true;
}
if e_expn.expn_data().macro_def_id.map(|id| cx.tcx.item_name(id)) == Some(assert_name) {
found = Some((e, e_expn));
}
false
})
.visit_expr(expr);
found
}
fn is_assert_arg(cx: &LateContext<'_>, expr: &Expr<'_>, assert_expn: ExpnId) -> bool {
if !expr.span.from_expansion() {
return true;
}
let result = macro_backtrace(expr.span).try_for_each(|macro_call| {
if macro_call.expn == assert_expn {
ControlFlow::Break(false)
} else {
match cx.tcx.item_name(macro_call.def_id) {
// `cfg!(debug_assertions)` in `debug_assert!`
sym::cfg => ControlFlow::CONTINUE,
// assert!(other_macro!(..))
_ => ControlFlow::Break(true),
}
}
});
match result {
ControlFlow::Break(is_assert_arg) => is_assert_arg,
ControlFlow::Continue(()) => true,
}
}
/// The format string doesn't exist in the HIR, so we reassemble it from source code
#[derive(Debug)]
pub struct FormatString {
/// Span of the whole format string literal, including `[r#]"`.
pub span: Span,
/// Snippet of the whole format string literal, including `[r#]"`.
pub snippet: String,
/// If the string is raw `r"..."`/`r#""#`, how many `#`s does it have on each side.
pub style: Option<usize>,
/// The unescaped value of the format string, e.g. `"val {}"` for the literal
/// `"val \u{2013} {}"`.
pub unescaped: String,
/// The format string split by format args like `{..}`.
pub parts: Vec<Symbol>,
}
impl FormatString {
fn new(cx: &LateContext<'_>, pieces: &Expr<'_>) -> Option<Self> {
// format_args!(r"a {} b \", 1);
//
// expands to
//
// ::core::fmt::Arguments::new_v1(&["a ", " b \\"],
// &[::core::fmt::ArgumentV1::new_display(&1)]);
//
// where `pieces` is the expression `&["a ", " b \\"]`. It has the span of `r"a {} b \"`
let span = pieces.span;
let snippet = snippet_opt(cx, span)?;
let (inner, style) = match tokenize(&snippet).next()?.kind {
TokenKind::Literal { kind, .. } => {
let style = match kind {
LiteralKind::Str { .. } => None,
LiteralKind::RawStr { n_hashes: Some(n), .. } => Some(n.into()),
_ => return None,
};
let start = style.map_or(1, |n| 2 + n);
let end = snippet.len() - style.map_or(1, |n| 1 + n);
(&snippet[start..end], style)
},
_ => return None,
};
let mode = if style.is_some() {
unescape::Mode::RawStr
} else {
unescape::Mode::Str
};
let mut unescaped = String::with_capacity(inner.len());
unescape_literal(inner, mode, &mut |_, ch| match ch {
Ok(ch) => unescaped.push(ch),
Err(e) if !e.is_fatal() => (),
Err(e) => panic!("{:?}", e),
});
let mut parts = Vec::new();
expr_visitor_no_bodies(|expr| {
if let ExprKind::Lit(lit) = &expr.kind {
if let LitKind::Str(symbol, _) = lit.node {
parts.push(symbol);
}
}
true
})
.visit_expr(pieces);
Some(Self {
span,
snippet,
style,
unescaped,
parts,
})
}
}
struct FormatArgsValues<'tcx> {
/// See `FormatArgsExpn::value_args`
value_args: Vec<&'tcx Expr<'tcx>>,
/// Maps an `rt::v1::Argument::position` or an `rt::v1::Count::Param` to its index in
/// `value_args`
pos_to_value_index: Vec<usize>,
/// Used to check if a value is declared inline & to resolve `InnerSpan`s.
format_string_span: SpanData,
}
impl<'tcx> FormatArgsValues<'tcx> {
fn new(args: &'tcx Expr<'tcx>, format_string_span: SpanData) -> Self {
let mut pos_to_value_index = Vec::new();
let mut value_args = Vec::new();
expr_visitor_no_bodies(|expr| {
if expr.span.ctxt() == args.span.ctxt() {
// ArgumentV1::new_<format_trait>(<val>)
// ArgumentV1::from_usize(<val>)
if let ExprKind::Call(callee, [val]) = expr.kind
&& let ExprKind::Path(QPath::TypeRelative(ty, _)) = callee.kind
&& let hir::TyKind::Path(QPath::Resolved(_, path)) = ty.kind
&& path.segments.last().unwrap().ident.name == sym::ArgumentV1
{
let val_idx = if val.span.ctxt() == expr.span.ctxt()
&& let ExprKind::Field(_, field) = val.kind
&& let Ok(idx) = field.name.as_str().parse()
{
// tuple index
idx
} else {
// assume the value expression is passed directly
pos_to_value_index.len()
};
pos_to_value_index.push(val_idx);
}
true
} else {
// assume that any expr with a differing span is a value
value_args.push(expr);
false
}
})
.visit_expr(args);
Self {
value_args,
pos_to_value_index,
format_string_span,
}
}
}
/// The positions of a format argument's value, precision and width
///
/// A position is an index into the second argument of `Arguments::new_v1[_formatted]`
#[derive(Debug, Default, Copy, Clone)]
struct ParamPosition {
/// The position stored in `rt::v1::Argument::position`.
value: usize,
/// The position stored in `rt::v1::FormatSpec::width` if it is a `Count::Param`.
width: Option<usize>,
/// The position stored in `rt::v1::FormatSpec::precision` if it is a `Count::Param`.
precision: Option<usize>,
}
impl<'tcx> Visitor<'tcx> for ParamPosition {
fn visit_expr_field(&mut self, field: &'tcx ExprField<'tcx>) {
fn parse_count(expr: &Expr<'_>) -> Option<usize> {
// ::core::fmt::rt::v1::Count::Param(1usize),
if let ExprKind::Call(ctor, [val]) = expr.kind
&& let ExprKind::Path(QPath::Resolved(_, path)) = ctor.kind
&& path.segments.last()?.ident.name == sym::Param
&& let ExprKind::Lit(lit) = &val.kind
&& let LitKind::Int(pos, _) = lit.node
{
Some(pos as usize)
} else {
None
}
}
match field.ident.name {
sym::position => {
if let ExprKind::Lit(lit) = &field.expr.kind
&& let LitKind::Int(pos, _) = lit.node
{
self.value = pos as usize;
}
},
sym::precision => {
self.precision = parse_count(field.expr);
},
sym::width => {
self.width = parse_count(field.expr);
},
_ => walk_expr(self, field.expr),
}
}
}
/// Parses the `fmt` arg of `Arguments::new_v1_formatted(pieces, args, fmt, _)`
fn parse_rt_fmt<'tcx>(fmt_arg: &'tcx Expr<'tcx>) -> Option<impl Iterator<Item = ParamPosition> + 'tcx> {
if let ExprKind::AddrOf(.., array) = fmt_arg.kind
&& let ExprKind::Array(specs) = array.kind
{
Some(specs.iter().map(|spec| {
let mut position = ParamPosition::default();
position.visit_expr(spec);
position
}))
} else {
None
}
}
/// `Span::from_inner`, but for `rustc_parse_format`'s `InnerSpan`
fn span_from_inner(base: SpanData, inner: rpf::InnerSpan) -> Span {
Span::new(
base.lo + BytePos::from_usize(inner.start),
base.lo + BytePos::from_usize(inner.end),
base.ctxt,
base.parent,
)
}
#[derive(Debug, Copy, Clone, PartialEq, Eq)]
pub enum FormatParamKind {
/// An implicit parameter , such as `{}` or `{:?}`.
Implicit,
/// A parameter with an explicit number, or an asterisk precision. e.g. `{1}`, `{0:?}`,
/// `{:.0$}` or `{:.*}`.
Numbered,
/// A named parameter with a named `value_arg`, such as the `x` in `format!("{x}", x = 1)`.
Named(Symbol),
/// An implicit named parameter, such as the `y` in `format!("{y}")`.
NamedInline(Symbol),
}
/// A `FormatParam` is any place in a `FormatArgument` that refers to a supplied value, e.g.
///
/// ```
/// let precision = 2;
/// format!("{:.precision$}", 0.1234);
/// ```
///
/// has two `FormatParam`s, a [`FormatParamKind::Implicit`] `.kind` with a `.value` of `0.1234`
/// and a [`FormatParamKind::NamedInline("precision")`] `.kind` with a `.value` of `2`
#[derive(Debug, Copy, Clone)]
pub struct FormatParam<'tcx> {
/// The expression this parameter refers to.
pub value: &'tcx Expr<'tcx>,
/// How this parameter refers to its `value`.
pub kind: FormatParamKind,
/// Span of the parameter, may be zero width. Includes the whitespace of implicit parameters.
///
/// ```text
/// format!("{}, { }, {0}, {name}", ...);
/// ^ ~~ ~ ~~~~
/// ```
pub span: Span,
}
impl<'tcx> FormatParam<'tcx> {
fn new(
mut kind: FormatParamKind,
position: usize,
inner: rpf::InnerSpan,
values: &FormatArgsValues<'tcx>,
) -> Option<Self> {
let value_index = *values.pos_to_value_index.get(position)?;
let value = *values.value_args.get(value_index)?;
let span = span_from_inner(values.format_string_span, inner);
// if a param is declared inline, e.g. `format!("{x}")`, the generated expr's span points
// into the format string
if let FormatParamKind::Named(name) = kind && values.format_string_span.contains(value.span.data()) {
kind = FormatParamKind::NamedInline(name);
}
Some(Self { value, kind, span })
}
}
/// Used by [width](https://doc.rust-lang.org/std/fmt/#width) and
/// [precision](https://doc.rust-lang.org/std/fmt/#precision) specifiers.
#[derive(Debug, Copy, Clone)]
pub enum Count<'tcx> {
/// Specified with a literal number, stores the value.
Is(usize, Span),
/// Specified using `$` and `*` syntaxes. The `*` format is still considered to be
/// `FormatParamKind::Numbered`.
Param(FormatParam<'tcx>),
/// Not specified.
Implied,
}
impl<'tcx> Count<'tcx> {
fn new(
count: rpf::Count<'_>,
position: Option<usize>,
inner: Option<rpf::InnerSpan>,
values: &FormatArgsValues<'tcx>,
) -> Option<Self> {
Some(match count {
rpf::Count::CountIs(val) => Self::Is(val, span_from_inner(values.format_string_span, inner?)),
rpf::Count::CountIsName(name, span) => Self::Param(FormatParam::new(
FormatParamKind::Named(Symbol::intern(name)),
position?,
span,
values,
)?),
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rpf::Count::CountIsParam(_) | rpf::Count::CountIsStar(_) => {
Self::Param(FormatParam::new(FormatParamKind::Numbered, position?, inner?, values)?)
},
rpf::Count::CountImplied => Self::Implied,
})
}
pub fn is_implied(self) -> bool {
matches!(self, Count::Implied)
}
pub fn param(self) -> Option<FormatParam<'tcx>> {
match self {
Count::Param(param) => Some(param),
_ => None,
}
}
}
/// Specification for the formatting of an argument in the format string. See
/// <https://doc.rust-lang.org/std/fmt/index.html#formatting-parameters> for the precise meanings.
#[derive(Debug)]
pub struct FormatSpec<'tcx> {
/// Optionally specified character to fill alignment with.
pub fill: Option<char>,
/// Optionally specified alignment.
pub align: Alignment,
/// Packed version of various flags provided, see [`rustc_parse_format::Flag`].
pub flags: u32,
/// Represents either the maximum width or the integer precision.
pub precision: Count<'tcx>,
/// The minimum width, will be padded according to `width`/`align`
pub width: Count<'tcx>,
/// The formatting trait used by the argument, e.g. `sym::Display` for `{}`, `sym::Debug` for
/// `{:?}`.
pub r#trait: Symbol,
pub trait_span: Option<Span>,
}
impl<'tcx> FormatSpec<'tcx> {
fn new(spec: rpf::FormatSpec<'_>, positions: ParamPosition, values: &FormatArgsValues<'tcx>) -> Option<Self> {
Some(Self {
fill: spec.fill,
align: spec.align,
flags: spec.flags,
precision: Count::new(spec.precision, positions.precision, spec.precision_span, values)?,
width: Count::new(spec.width, positions.width, spec.width_span, values)?,
r#trait: match spec.ty {
"" => sym::Display,
"?" => sym::Debug,
"o" => sym!(Octal),
"x" => sym!(LowerHex),
"X" => sym!(UpperHex),
"p" => sym::Pointer,
"b" => sym!(Binary),
"e" => sym!(LowerExp),
"E" => sym!(UpperExp),
_ => return None,
},
trait_span: spec
.ty_span
.map(|span| span_from_inner(values.format_string_span, span)),
})
}
/// Returns true if this format spec is unchanged from the default. e.g. returns true for `{}`,
/// `{foo}` and `{2}`, but false for `{:?}`, `{foo:5}` and `{3:.5}`
pub fn is_default(&self) -> bool {
self.r#trait == sym::Display
&& self.width.is_implied()
&& self.precision.is_implied()
&& self.align == Alignment::AlignUnknown
&& self.flags == 0
}
}
/// A format argument, such as `{}`, `{foo:?}`.
#[derive(Debug)]
pub struct FormatArg<'tcx> {
/// The parameter the argument refers to.
pub param: FormatParam<'tcx>,
/// How to format `param`.
pub format: FormatSpec<'tcx>,
/// span of the whole argument, `{..}`.
pub span: Span,
}
/// A parsed `format_args!` expansion.
#[derive(Debug)]
pub struct FormatArgsExpn<'tcx> {
/// The format string literal.
pub format_string: FormatString,
// The format arguments, such as `{:?}`.
pub args: Vec<FormatArg<'tcx>>,
/// Has an added newline due to `println!()`/`writeln!()`/etc. The last format string part will
/// include this added newline.
pub newline: bool,
/// Values passed after the format string and implicit captures. `[1, z + 2, x]` for
/// `format!("{x} {} {y}", 1, z + 2)`.
value_args: Vec<&'tcx Expr<'tcx>>,
}
impl<'tcx> FormatArgsExpn<'tcx> {
pub fn parse(cx: &LateContext<'_>, expr: &'tcx Expr<'tcx>) -> Option<Self> {
let macro_name = macro_backtrace(expr.span)
.map(|macro_call| cx.tcx.item_name(macro_call.def_id))
.find(|&name| matches!(name, sym::const_format_args | sym::format_args | sym::format_args_nl))?;
let newline = macro_name == sym::format_args_nl;
// ::core::fmt::Arguments::new_v1(pieces, args)
// ::core::fmt::Arguments::new_v1_formatted(pieces, args, fmt, _unsafe_arg)
if let ExprKind::Call(callee, [pieces, args, rest @ ..]) = expr.kind
&& let ExprKind::Path(QPath::TypeRelative(ty, seg)) = callee.kind
&& is_path_diagnostic_item(cx, ty, sym::Arguments)
&& matches!(seg.ident.as_str(), "new_v1" | "new_v1_formatted")
{
let format_string = FormatString::new(cx, pieces)?;
let mut parser = rpf::Parser::new(
&format_string.unescaped,
format_string.style,
Some(format_string.snippet.clone()),
// `format_string.unescaped` does not contain the appended newline
false,
rpf::ParseMode::Format,
);
let parsed_args = parser
.by_ref()
.filter_map(|piece| match piece {
rpf::Piece::NextArgument(a) => Some(a),
rpf::Piece::String(_) => None,
})
.collect_vec();
if !parser.errors.is_empty() {
return None;
}
let positions = if let Some(fmt_arg) = rest.first() {
// If the argument contains format specs, `new_v1_formatted(_, _, fmt, _)`, parse
// them.
Either::Left(parse_rt_fmt(fmt_arg)?)
} else {
// If no format specs are given, the positions are in the given order and there are
// no `precision`/`width`s to consider.
Either::Right((0..).map(|n| ParamPosition {
value: n,
width: None,
precision: None,
}))
};
let values = FormatArgsValues::new(args, format_string.span.data());
let args = izip!(positions, parsed_args, parser.arg_places)
.map(|(position, parsed_arg, arg_span)| {
Some(FormatArg {
param: FormatParam::new(
match parsed_arg.position {
rpf::Position::ArgumentImplicitlyIs(_) => FormatParamKind::Implicit,
rpf::Position::ArgumentIs(_) => FormatParamKind::Numbered,
// NamedInline is handled by `FormatParam::new()`
rpf::Position::ArgumentNamed(name) => FormatParamKind::Named(Symbol::intern(name)),
},
position.value,
parsed_arg.position_span,
&values,
)?,
format: FormatSpec::new(parsed_arg.format, position, &values)?,
span: span_from_inner(values.format_string_span, arg_span),
})
})
.collect::<Option<Vec<_>>>()?;
Some(Self {
format_string,
args,
value_args: values.value_args,
newline,
})
} else {
None
}
}
pub fn find_nested(cx: &LateContext<'tcx>, expr: &'tcx Expr<'tcx>, expn_id: ExpnId) -> Option<Self> {
let mut format_args = None;
expr_visitor_no_bodies(|e| {
if format_args.is_some() {
return false;
}
let e_ctxt = e.span.ctxt();
if e_ctxt == expr.span.ctxt() {
return true;
}
if e_ctxt.outer_expn().is_descendant_of(expn_id) {
format_args = FormatArgsExpn::parse(cx, e);
}
false
})
.visit_expr(expr);
format_args
}
/// Source callsite span of all inputs
pub fn inputs_span(&self) -> Span {
match *self.value_args {
[] => self.format_string.span,
[.., last] => self
.format_string
.span
.to(hygiene::walk_chain(last.span, self.format_string.span.ctxt())),
}
}
/// Iterator of all format params, both values and those referenced by `width`/`precision`s.
pub fn params(&'tcx self) -> impl Iterator<Item = FormatParam<'tcx>> {
self.args
.iter()
.flat_map(|arg| [Some(arg.param), arg.format.precision.param(), arg.format.width.param()])
.flatten()
}
}
/// A node with a `HirId` and a `Span`
pub trait HirNode {
fn hir_id(&self) -> HirId;
fn span(&self) -> Span;
}
macro_rules! impl_hir_node {
($($t:ident),*) => {
$(impl HirNode for hir::$t<'_> {
fn hir_id(&self) -> HirId {
self.hir_id
}
fn span(&self) -> Span {
self.span
}
})*
};
}
impl_hir_node!(Expr, Pat);
impl HirNode for hir::Item<'_> {
fn hir_id(&self) -> HirId {
self.hir_id()
}
fn span(&self) -> Span {
self.span
}
}