From b6673b344a8135692ae2dfb74b0787c2bb62095c Mon Sep 17 00:00:00 2001
From: Mara Bos <m-ou.se@m-ou.se>
Date: Wed, 6 Dec 2023 00:34:39 +0100
Subject: [PATCH 1/3] Don't remove inlined arguments from format_args!().
format_args!("{}", 12345u8) shouldn't disable the out-of-range check
of the argument.
---
compiler/rustc_ast_lowering/src/format.rs | 135 ++++++++--------------
1 file changed, 49 insertions(+), 86 deletions(-)
diff --git a/compiler/rustc_ast_lowering/src/format.rs b/compiler/rustc_ast_lowering/src/format.rs
index 8fa2cae43bfdd..6e46a20131912 100644
--- a/compiler/rustc_ast_lowering/src/format.rs
+++ b/compiler/rustc_ast_lowering/src/format.rs
@@ -13,15 +13,12 @@ use std::borrow::Cow;
impl<'hir> LoweringContext<'_, 'hir> {
pub(crate) fn lower_format_args(&mut self, sp: Span, fmt: &FormatArgs) -> hir::ExprKind<'hir> {
- // Never call the const constructor of `fmt::Arguments` if the
- // format_args!() had any arguments _before_ flattening/inlining.
- let allow_const = fmt.arguments.all_args().is_empty();
let mut fmt = Cow::Borrowed(fmt);
if self.tcx.sess.opts.unstable_opts.flatten_format_args {
fmt = flatten_format_args(fmt);
fmt = inline_literals(fmt);
}
- expand_format_args(self, sp, &fmt, allow_const)
+ expand_format_args(self, sp, &fmt)
}
}
@@ -111,10 +108,10 @@ fn flatten_format_args(mut fmt: Cow<'_, FormatArgs>) -> Cow<'_, FormatArgs> {
/// into
///
/// `format_args!("Hello, World! 123 {}", x)`.
-fn inline_literals(mut fmt: Cow<'_, FormatArgs>) -> Cow<'_, FormatArgs> {
- let mut was_inlined = vec![false; fmt.arguments.all_args().len()];
- let mut inlined_anything = false;
-
+///
+/// Except it doesn't actually remove the inlined arguments,
+/// to make sure they are still checked later on (e.g. for out-of-range values).
+fn inline_literals<'a>(mut fmt: Cow<'a, FormatArgs>) -> Cow<'a, FormatArgs> {
for i in 0..fmt.template.len() {
let FormatArgsPiece::Placeholder(placeholder) = &fmt.template[i] else { continue };
let Ok(arg_index) = placeholder.argument.index else { continue };
@@ -143,38 +140,8 @@ fn inline_literals(mut fmt: Cow<'_, FormatArgs>) -> Cow<'_, FormatArgs> {
let fmt = fmt.to_mut();
// Replace the placeholder with the literal.
fmt.template[i] = FormatArgsPiece::Literal(literal);
- was_inlined[arg_index] = true;
- inlined_anything = true;
}
}
-
- // Remove the arguments that were inlined.
- if inlined_anything {
- let fmt = fmt.to_mut();
-
- let mut remove = was_inlined;
-
- // Don't remove anything that's still used.
- for_all_argument_indexes(&mut fmt.template, |index| remove[*index] = false);
-
- // Drop all the arguments that are marked for removal.
- let mut remove_it = remove.iter();
- fmt.arguments.all_args_mut().retain(|_| remove_it.next() != Some(&true));
-
- // Calculate the mapping of old to new indexes for the remaining arguments.
- let index_map: Vec<usize> = remove
- .into_iter()
- .scan(0, |i, remove| {
- let mapped = *i;
- *i += !remove as usize;
- Some(mapped)
- })
- .collect();
-
- // Correct the indexes that refer to arguments that have shifted position.
- for_all_argument_indexes(&mut fmt.template, |index| *index = index_map[*index]);
- }
-
fmt
}
@@ -353,7 +320,6 @@ fn expand_format_args<'hir>(
ctx: &mut LoweringContext<'_, 'hir>,
macsp: Span,
fmt: &FormatArgs,
- allow_const: bool,
) -> hir::ExprKind<'hir> {
let mut incomplete_lit = String::new();
let lit_pieces =
@@ -422,7 +388,7 @@ fn expand_format_args<'hir>(
let arguments = fmt.arguments.all_args();
- if allow_const && arguments.is_empty() && argmap.is_empty() {
+ if arguments.is_empty() && argmap.is_empty() {
// Generate:
// <core::fmt::Arguments>::new_const(lit_pieces)
let new = ctx.arena.alloc(ctx.expr_lang_item_type_relative(
@@ -445,30 +411,7 @@ fn expand_format_args<'hir>(
&& argmap.iter().enumerate().all(|(i, (&(j, _), _))| i == j)
&& arguments.iter().skip(1).all(|arg| !may_contain_yield_point(&arg.expr));
- let args = if arguments.is_empty() {
- // Generate:
- // &<core::fmt::Argument>::none()
- //
- // Note:
- // `none()` just returns `[]`. We use `none()` rather than `[]` to limit the lifetime.
- //
- // This makes sure that this still fails to compile, even when the argument is inlined:
- //
- // ```
- // let f = format_args!("{}", "a");
- // println!("{f}"); // error E0716
- // ```
- //
- // Cases where keeping the object around is allowed, such as `format_args!("a")`,
- // are handled above by the `allow_const` case.
- let none_fn = ctx.arena.alloc(ctx.expr_lang_item_type_relative(
- macsp,
- hir::LangItem::FormatArgument,
- sym::none,
- ));
- let none = ctx.expr_call(macsp, none_fn, &[]);
- ctx.expr(macsp, hir::ExprKind::AddrOf(hir::BorrowKind::Ref, hir::Mutability::Not, none))
- } else if use_simple_array {
+ let args = if use_simple_array {
// Generate:
// &[
// <core::fmt::Argument>::new_display(&arg0),
@@ -505,26 +448,47 @@ fn expand_format_args<'hir>(
// }
let args_ident = Ident::new(sym::args, macsp);
let (args_pat, args_hir_id) = ctx.pat_ident(macsp, args_ident);
- let args = ctx.arena.alloc_from_iter(argmap.iter().map(
- |(&(arg_index, ty), &placeholder_span)| {
- let arg = &arguments[arg_index];
- let placeholder_span =
- placeholder_span.unwrap_or(arg.expr.span).with_ctxt(macsp.ctxt());
- let arg_span = match arg.kind {
- FormatArgumentKind::Captured(_) => placeholder_span,
- _ => arg.expr.span.with_ctxt(macsp.ctxt()),
- };
- let args_ident_expr = ctx.expr_ident(macsp, args_ident, args_hir_id);
- let arg = ctx.arena.alloc(ctx.expr(
- arg_span,
- hir::ExprKind::Field(
- args_ident_expr,
- Ident::new(sym::integer(arg_index), macsp),
- ),
- ));
- make_argument(ctx, placeholder_span, arg, ty)
- },
- ));
+ let args = if argmap.is_empty() {
+ // Generate `<core::fmt::Argument>::none()` instead of `[]`
+ //
+ // `none()` just returns `[]`. We use `none()` rather than `[]` to limit the lifetime.
+ //
+ // This makes sure that this still fails to compile, even when the argument is inlined:
+ //
+ // ```
+ // let f = format_args!("{}", "a");
+ // println!("{f}"); // error E0716
+ // ```
+ let none_fn = ctx.arena.alloc(ctx.expr_lang_item_type_relative(
+ macsp,
+ hir::LangItem::FormatArgument,
+ sym::none,
+ ));
+ ctx.expr_call(macsp, none_fn, &[])
+ } else {
+ let elements = ctx.arena.alloc_from_iter(argmap.iter().map(
+ |(&(arg_index, ty), &placeholder_span)| {
+ let arg = &arguments[arg_index];
+ let placeholder_span =
+ placeholder_span.unwrap_or(arg.expr.span).with_ctxt(macsp.ctxt());
+ let arg_span = match arg.kind {
+ FormatArgumentKind::Captured(_) => placeholder_span,
+ _ => arg.expr.span.with_ctxt(macsp.ctxt()),
+ };
+ let args_ident_expr = ctx.expr_ident(macsp, args_ident, args_hir_id);
+ let arg = ctx.arena.alloc(ctx.expr(
+ arg_span,
+ hir::ExprKind::Field(
+ args_ident_expr,
+ Ident::new(sym::integer(arg_index), macsp),
+ ),
+ ));
+ make_argument(ctx, placeholder_span, arg, ty)
+ },
+ ));
+ let array = ctx.expr(macsp, hir::ExprKind::Array(elements));
+ ctx.arena.alloc(array)
+ };
let elements = ctx.arena.alloc_from_iter(arguments.iter().map(|arg| {
let arg_expr = ctx.lower_expr(&arg.expr);
ctx.expr(
@@ -533,8 +497,7 @@ fn expand_format_args<'hir>(
)
}));
let args_tuple = ctx.arena.alloc(ctx.expr(macsp, hir::ExprKind::Tup(elements)));
- let array = ctx.arena.alloc(ctx.expr(macsp, hir::ExprKind::Array(args)));
- let match_arms = ctx.arena.alloc_from_iter([ctx.arm(args_pat, array)]);
+ let match_arms = ctx.arena.alloc_from_iter([ctx.arm(args_pat, args)]);
let match_expr = ctx.arena.alloc(ctx.expr_match(
macsp,
args_tuple,
From 95590b5c6d07885e2b1fa2aa36b7a4d3b460f85e Mon Sep 17 00:00:00 2001
From: Mara Bos <m-ou.se@m-ou.se>
Date: Wed, 6 Dec 2023 00:36:09 +0100
Subject: [PATCH 2/3] Update test output.
---
tests/ui/unpretty/flattened-format-args.stdout | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/tests/ui/unpretty/flattened-format-args.stdout b/tests/ui/unpretty/flattened-format-args.stdout
index a8fe8da002472..f84c7f01dfa82 100644
--- a/tests/ui/unpretty/flattened-format-args.stdout
+++ b/tests/ui/unpretty/flattened-format-args.stdout
@@ -11,6 +11,9 @@ fn main() {
{
::std::io::_print(<#[lang = "format_arguments"]>::new_v1(&["a 123 b ",
" xyz\n"],
- &[<#[lang = "format_argument"]>::new_display(&x)]));
+ &match (&123, &x, &"xyz") {
+ args =>
+ [<#[lang = "format_argument"]>::new_display(args.1)],
+ }));
};
}
From 1dcf8c8c38925e18910debd6933b2a86dfc3ee6e Mon Sep 17 00:00:00 2001
From: Mara Bos <m-ou.se@m-ou.se>
Date: Wed, 6 Dec 2023 00:40:34 +0100
Subject: [PATCH 3/3] Add test.
---
tests/ui/fmt/format-args-out-of-range.rs | 4 ++++
tests/ui/fmt/format-args-out-of-range.stderr | 11 +++++++++++
2 files changed, 15 insertions(+)
create mode 100644 tests/ui/fmt/format-args-out-of-range.rs
create mode 100644 tests/ui/fmt/format-args-out-of-range.stderr
diff --git a/tests/ui/fmt/format-args-out-of-range.rs b/tests/ui/fmt/format-args-out-of-range.rs
new file mode 100644
index 0000000000000..774631656b111
--- /dev/null
+++ b/tests/ui/fmt/format-args-out-of-range.rs
@@ -0,0 +1,4 @@
+fn main() {
+ println!("{}", 12345u8);
+ //~^ ERROR: literal out of range
+}
diff --git a/tests/ui/fmt/format-args-out-of-range.stderr b/tests/ui/fmt/format-args-out-of-range.stderr
new file mode 100644
index 0000000000000..62f00f63882e1
--- /dev/null
+++ b/tests/ui/fmt/format-args-out-of-range.stderr
@@ -0,0 +1,11 @@
+error: literal out of range for `u8`
+ --> $DIR/format-args-out-of-range.rs:2:20
+ |
+LL | println!("{}", 12345u8);
+ | ^^^^^^^
+ |
+ = note: the literal `12345u8` does not fit into the type `u8` whose range is `0..=255`
+ = note: `#[deny(overflowing_literals)]` on by default
+
+error: aborting due to 1 previous error
+