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Update comments in rustc_ast_lowering/src/format.rs.

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This commit is contained in:
Mara Bos 2023-01-12 20:06:38 +01:00
parent 0a1934a32c
commit 8a23ad17f8
1 changed files with 51 additions and 22 deletions
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73
compiler/rustc_ast_lowering/src/format.rs
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@ -22,14 +22,19 @@ enum ArgumentType {
Usize,
}
/// Generate a hir expression representing an argument to a format_args invocation.
///
/// Generates:
///
/// ```text
/// <core::fmt::ArgumentV1>::new_…(arg)
/// ```
fn make_argument<'hir>(
ctx: &mut LoweringContext<'_, 'hir>,
sp: Span,
arg: &'hir hir::Expr<'hir>,
ty: ArgumentType,
) -> hir::Expr<'hir> {
// Generate:
// ::core::fmt::ArgumentV1::new_…(arg)
use ArgumentType::*;
use FormatTrait::*;
let new_fn = ctx.arena.alloc(ctx.expr_lang_item_type_relative(
@ -51,14 +56,31 @@ fn make_argument<'hir>(
ctx.expr_call_mut(sp, new_fn, std::slice::from_ref(arg))
}
/// Generate a hir expression for a format_args Count.
///
/// Generates:
///
/// ```text
/// <core::fmt::rt::v1::Count>::Is(…)
/// ```
///
/// or
///
/// ```text
/// <core::fmt::rt::v1::Count>::Param(…)
/// ```
///
/// or
///
/// ```text
/// <core::fmt::rt::v1::Count>::Implied
/// ```
fn make_count<'hir>(
ctx: &mut LoweringContext<'_, 'hir>,
sp: Span,
count: &Option<FormatCount>,
argmap: &mut FxIndexSet<(usize, ArgumentType)>,
) -> hir::Expr<'hir> {
// Generate:
// ::core::fmt::rt::v1::Count::…(…)
match count {
Some(FormatCount::Literal(n)) => {
let count_is = ctx.arena.alloc(ctx.expr_lang_item_type_relative(
@ -87,21 +109,26 @@ fn make_count<'hir>(
}
}
/// Generate a hir expression for a format_args placeholder specification.
///
/// Generates
///
/// ```text
/// <core::fmt::rt::v1::Argument::new(
/// …usize, // position
/// '…', // fill
/// <core::fmt::rt::v1::Alignment>::…, // alignment
/// …u32, // flags
/// <core::fmt::rt::v1::Count::…>, // width
/// <core::fmt::rt::v1::Count::…>, // precision
/// )
/// ```
fn make_format_spec<'hir>(
ctx: &mut LoweringContext<'_, 'hir>,
sp: Span,
placeholder: &FormatPlaceholder,
argmap: &mut FxIndexSet<(usize, ArgumentType)>,
) -> hir::Expr<'hir> {
// Generate:
// ::core::fmt::rt::v1::Argument::new(
// 0usize, // position
// ' ', // fill
// ::core::fmt::rt::v1::Alignment::Unknown,
// 0u32, // flags
// ::core::fmt::rt::v1::Count::Implied, // width
// ::core::fmt::rt::v1::Count::Implied, // precision
// )
let position = match placeholder.argument.index {
Ok(arg_index) => {
let (i, _) =
@ -203,9 +230,10 @@ fn expand_format_args<'hir>(
let args = if use_simple_array {
// Generate:
// &[
// ::core::fmt::ArgumentV1::new_display(&arg0),
// ::core::fmt::ArgumentV1::new_lower_hex(&arg1),
// ::core::fmt::ArgumentV1::new_debug(&arg2),
// <core::fmt::ArgumentV1>::new_display(&arg0),
// <core::fmt::ArgumentV1>::new_lower_hex(&arg1),
// <core::fmt::ArgumentV1>::new_debug(&arg2),
// …
// ]
let elements: Vec<_> = arguments
.iter()
@ -223,11 +251,12 @@ fn expand_format_args<'hir>(
ctx.expr_array_ref(macsp, ctx.arena.alloc_from_iter(elements))
} else {
// Generate:
// &match (&arg0, &arg1, &arg2) {
// &match (&arg0, &arg1, &…) {
// args => [
// ::core::fmt::ArgumentV1::new_display(args.0),
// ::core::fmt::ArgumentV1::new_lower_hex(args.1),
// ::core::fmt::ArgumentV1::new_debug(args.0),
// <core::fmt::ArgumentV1>::new_display(args.0),
// <core::fmt::ArgumentV1>::new_lower_hex(args.1),
// <core::fmt::ArgumentV1>::new_debug(args.0),
// …
// ]
// }
let args_ident = Ident::new(sym::args, macsp);
@ -277,7 +306,7 @@ fn expand_format_args<'hir>(
if let Some(format_options) = format_options {
// Generate:
// ::core::fmt::Arguments::new_v1_formatted(
// <core::fmt::Arguments>::new_v1_formatted(
// lit_pieces,
// args,
// format_options,
@ -307,7 +336,7 @@ fn expand_format_args<'hir>(
hir::ExprKind::Call(new_v1_formatted, args)
} else {
// Generate:
// ::core::fmt::Arguments::new_v1(
// <core::fmt::Arguments>::new_v1(
// lit_pieces,
// args,
// )