diff --git a/compiler/rustc_builtin_macros/messages.ftl b/compiler/rustc_builtin_macros/messages.ftl
index 207ae8ad844bb..dda466b026d91 100644
--- a/compiler/rustc_builtin_macros/messages.ftl
+++ b/compiler/rustc_builtin_macros/messages.ftl
@@ -137,6 +137,20 @@ builtin_macros_format_positional_after_named = positional arguments cannot follo
.label = positional arguments must be before named arguments
.named_args = named argument
+builtin_macros_format_redundant_args = redundant {$n ->
+ [one] argument
+ *[more] arguments
+ }
+ .help = {$n ->
+ [one] the formatting string already captures the binding directly, it doesn't need to be included in the argument list
+ *[more] the formatting strings already captures the bindings directly, they don't need to be included in the argument list
+ }
+ .note = {$n ->
+ [one] the formatting specifier is referencing the binding already
+ *[more] the formatting specifiers are referencing the bindings already
+ }
+ .suggestion = this can be removed
+
builtin_macros_format_remove_raw_ident = remove the `r#`
builtin_macros_format_requires_string = requires at least a format string argument
diff --git a/compiler/rustc_builtin_macros/src/errors.rs b/compiler/rustc_builtin_macros/src/errors.rs
index 1238773d58b55..fde4270334b67 100644
--- a/compiler/rustc_builtin_macros/src/errors.rs
+++ b/compiler/rustc_builtin_macros/src/errors.rs
@@ -646,6 +646,27 @@ pub(crate) struct FormatPositionalMismatch {
pub(crate) highlight: SingleLabelManySpans,
}
+#[derive(Diagnostic)]
+#[diag(builtin_macros_format_redundant_args)]
+pub(crate) struct FormatRedundantArgs {
+ #[primary_span]
+ pub(crate) span: MultiSpan,
+ pub(crate) n: usize,
+
+ #[note]
+ pub(crate) note: MultiSpan,
+
+ #[subdiagnostic]
+ pub(crate) sugg: Option<FormatRedundantArgsSugg>,
+}
+
+#[derive(Subdiagnostic)]
+#[multipart_suggestion(builtin_macros_suggestion, applicability = "machine-applicable")]
+pub(crate) struct FormatRedundantArgsSugg {
+ #[suggestion_part(code = "")]
+ pub(crate) spans: Vec<Span>,
+}
+
#[derive(Diagnostic)]
#[diag(builtin_macros_test_case_non_item)]
pub(crate) struct TestCaseNonItem {
diff --git a/compiler/rustc_builtin_macros/src/format.rs b/compiler/rustc_builtin_macros/src/format.rs
index 8397b5e4221c9..7c78be17653f3 100644
--- a/compiler/rustc_builtin_macros/src/format.rs
+++ b/compiler/rustc_builtin_macros/src/format.rs
@@ -1,3 +1,4 @@
+use parse::Position::ArgumentNamed;
use rustc_ast::ptr::P;
use rustc_ast::tokenstream::TokenStream;
use rustc_ast::{token, StmtKind};
@@ -7,7 +8,9 @@ use rustc_ast::{
FormatDebugHex, FormatOptions, FormatPlaceholder, FormatSign, FormatTrait,
};
use rustc_data_structures::fx::FxHashSet;
-use rustc_errors::{Applicability, MultiSpan, PResult, SingleLabelManySpans};
+use rustc_errors::{
+ Applicability, DiagnosticBuilder, ErrorGuaranteed, MultiSpan, PResult, SingleLabelManySpans,
+};
use rustc_expand::base::{self, *};
use rustc_parse_format as parse;
use rustc_span::symbol::{Ident, Symbol};
@@ -357,8 +360,8 @@ fn make_format_args(
let mut unfinished_literal = String::new();
let mut placeholder_index = 0;
- for piece in pieces {
- match piece {
+ for piece in &pieces {
+ match *piece {
parse::Piece::String(s) => {
unfinished_literal.push_str(s);
}
@@ -506,7 +509,17 @@ fn make_format_args(
// If there's a lot of unused arguments,
// let's check if this format arguments looks like another syntax (printf / shell).
let detect_foreign_fmt = unused.len() > args.explicit_args().len() / 2;
- report_missing_placeholders(ecx, unused, detect_foreign_fmt, str_style, fmt_str, fmt_span);
+ report_missing_placeholders(
+ ecx,
+ unused,
+ &used,
+ &args,
+ &pieces,
+ detect_foreign_fmt,
+ str_style,
+ fmt_str,
+ fmt_span,
+ );
}
// Only check for unused named argument names if there are no other errors to avoid causing
@@ -573,6 +586,9 @@ fn invalid_placeholder_type_error(
fn report_missing_placeholders(
ecx: &mut ExtCtxt<'_>,
unused: Vec<(Span, bool)>,
+ used: &[bool],
+ args: &FormatArguments,
+ pieces: &[parse::Piece<'_>],
detect_foreign_fmt: bool,
str_style: Option<usize>,
fmt_str: &str,
@@ -591,6 +607,26 @@ fn report_missing_placeholders(
})
};
+ let placeholders = pieces
+ .iter()
+ .filter_map(|piece| {
+ if let parse::Piece::NextArgument(argument) = piece && let ArgumentNamed(binding) = argument.position {
+ let span = fmt_span.from_inner(InnerSpan::new(argument.position_span.start, argument.position_span.end));
+ Some((span, binding))
+ } else { None }
+ })
+ .collect::<Vec<_>>();
+
+ if !placeholders.is_empty() {
+ if let Some(mut new_diag) =
+ report_redundant_format_arguments(ecx, &args, used, placeholders)
+ {
+ diag.cancel();
+ new_diag.emit();
+ return;
+ }
+ }
+
// Used to ensure we only report translations for *one* kind of foreign format.
let mut found_foreign = false;
@@ -678,6 +714,76 @@ fn report_missing_placeholders(
diag.emit();
}
+/// This function detects and reports unused format!() arguments that are
+/// redundant due to implicit captures (e.g. `format!("{x}", x)`).
+fn report_redundant_format_arguments<'a>(
+ ecx: &mut ExtCtxt<'a>,
+ args: &FormatArguments,
+ used: &[bool],
+ placeholders: Vec<(Span, &str)>,
+) -> Option<DiagnosticBuilder<'a, ErrorGuaranteed>> {
+ let mut fmt_arg_indices = vec![];
+ let mut args_spans = vec![];
+ let mut fmt_spans = vec![];
+
+ for (i, unnamed_arg) in args.unnamed_args().iter().enumerate().rev() {
+ let Some(ty) = unnamed_arg.expr.to_ty() else { continue };
+ let Some(argument_binding) = ty.kind.is_simple_path() else { continue };
+ let argument_binding = argument_binding.as_str();
+
+ if used[i] {
+ continue;
+ }
+
+ let matching_placeholders = placeholders
+ .iter()
+ .filter(|(_, inline_binding)| argument_binding == *inline_binding)
+ .map(|(span, _)| span)
+ .collect::<Vec<_>>();
+
+ if !matching_placeholders.is_empty() {
+ fmt_arg_indices.push(i);
+ args_spans.push(unnamed_arg.expr.span);
+ for span in &matching_placeholders {
+ if fmt_spans.contains(*span) {
+ continue;
+ }
+ fmt_spans.push(**span);
+ }
+ }
+ }
+
+ if !args_spans.is_empty() {
+ let multispan = MultiSpan::from(fmt_spans);
+ let mut suggestion_spans = vec![];
+
+ for (arg_span, fmt_arg_idx) in args_spans.iter().zip(fmt_arg_indices.iter()) {
+ let span = if fmt_arg_idx + 1 == args.explicit_args().len() {
+ *arg_span
+ } else {
+ arg_span.until(args.explicit_args()[*fmt_arg_idx + 1].expr.span)
+ };
+
+ suggestion_spans.push(span);
+ }
+
+ let sugg = if args.named_args().len() == 0 {
+ Some(errors::FormatRedundantArgsSugg { spans: suggestion_spans })
+ } else {
+ None
+ };
+
+ return Some(ecx.create_err(errors::FormatRedundantArgs {
+ n: args_spans.len(),
+ span: MultiSpan::from(args_spans),
+ note: multispan,
+ sugg,
+ }));
+ }
+
+ None
+}
+
/// Handle invalid references to positional arguments. Output different
/// errors for the case where all arguments are positional and for when
/// there are named arguments or numbered positional arguments in the
diff --git a/tests/ui/did_you_mean/issue-105225-named-args.rs b/tests/ui/did_you_mean/issue-105225-named-args.rs
new file mode 100644
index 0000000000000..38e817765769f
--- /dev/null
+++ b/tests/ui/did_you_mean/issue-105225-named-args.rs
@@ -0,0 +1,10 @@
+fn main() {
+ let x = "x";
+ let y = "y";
+
+ println!("{x}", x, x = y);
+ //~^ ERROR: redundant argument
+
+ println!("{x}", x = y, x = y);
+ //~^ ERROR: duplicate argument named `x`
+}
diff --git a/tests/ui/did_you_mean/issue-105225-named-args.stderr b/tests/ui/did_you_mean/issue-105225-named-args.stderr
new file mode 100644
index 0000000000000..72204102ef6cc
--- /dev/null
+++ b/tests/ui/did_you_mean/issue-105225-named-args.stderr
@@ -0,0 +1,22 @@
+error: redundant argument
+ --> $DIR/issue-105225-named-args.rs:5:21
+ |
+LL | println!("{x}", x, x = y);
+ | ^
+ |
+note: the formatting specifier is referencing the binding already
+ --> $DIR/issue-105225-named-args.rs:5:16
+ |
+LL | println!("{x}", x, x = y);
+ | ^
+
+error: duplicate argument named `x`
+ --> $DIR/issue-105225-named-args.rs:8:28
+ |
+LL | println!("{x}", x = y, x = y);
+ | - ^ duplicate argument
+ | |
+ | previously here
+
+error: aborting due to 2 previous errors
+
diff --git a/tests/ui/did_you_mean/issue-105225.fixed b/tests/ui/did_you_mean/issue-105225.fixed
new file mode 100644
index 0000000000000..f756be615a1bb
--- /dev/null
+++ b/tests/ui/did_you_mean/issue-105225.fixed
@@ -0,0 +1,21 @@
+// run-rustfix
+
+fn main() {
+ let x = "x";
+ let y = "y";
+
+ println!("{x}", );
+ //~^ ERROR: redundant argument
+
+ println!("{x} {}", x, );
+ //~^ ERROR: redundant argument
+
+ println!("{} {x}", x, );
+ //~^ ERROR: redundant argument
+
+ println!("{x} {y}", );
+ //~^ ERROR: redundant arguments
+
+ println!("{} {} {x} {y} {}", x, x, x, );
+ //~^ ERROR: redundant arguments
+}
diff --git a/tests/ui/did_you_mean/issue-105225.rs b/tests/ui/did_you_mean/issue-105225.rs
new file mode 100644
index 0000000000000..91cdf0eb28f6f
--- /dev/null
+++ b/tests/ui/did_you_mean/issue-105225.rs
@@ -0,0 +1,21 @@
+// run-rustfix
+
+fn main() {
+ let x = "x";
+ let y = "y";
+
+ println!("{x}", x);
+ //~^ ERROR: redundant argument
+
+ println!("{x} {}", x, x);
+ //~^ ERROR: redundant argument
+
+ println!("{} {x}", x, x);
+ //~^ ERROR: redundant argument
+
+ println!("{x} {y}", x, y);
+ //~^ ERROR: redundant arguments
+
+ println!("{} {} {x} {y} {}", x, x, x, y, y);
+ //~^ ERROR: redundant arguments
+}
diff --git a/tests/ui/did_you_mean/issue-105225.stderr b/tests/ui/did_you_mean/issue-105225.stderr
new file mode 100644
index 0000000000000..5fb46222bee59
--- /dev/null
+++ b/tests/ui/did_you_mean/issue-105225.stderr
@@ -0,0 +1,72 @@
+error: redundant argument
+ --> $DIR/issue-105225.rs:7:21
+ |
+LL | println!("{x}", x);
+ | ^ help: this can be removed
+ |
+note: the formatting specifier is referencing the binding already
+ --> $DIR/issue-105225.rs:7:16
+ |
+LL | println!("{x}", x);
+ | ^
+
+error: redundant argument
+ --> $DIR/issue-105225.rs:10:27
+ |
+LL | println!("{x} {}", x, x);
+ | ^ help: this can be removed
+ |
+note: the formatting specifier is referencing the binding already
+ --> $DIR/issue-105225.rs:10:16
+ |
+LL | println!("{x} {}", x, x);
+ | ^
+
+error: redundant argument
+ --> $DIR/issue-105225.rs:13:27
+ |
+LL | println!("{} {x}", x, x);
+ | ^ help: this can be removed
+ |
+note: the formatting specifier is referencing the binding already
+ --> $DIR/issue-105225.rs:13:19
+ |
+LL | println!("{} {x}", x, x);
+ | ^
+
+error: redundant arguments
+ --> $DIR/issue-105225.rs:16:25
+ |
+LL | println!("{x} {y}", x, y);
+ | ^ ^
+ |
+note: the formatting specifiers are referencing the bindings already
+ --> $DIR/issue-105225.rs:16:16
+ |
+LL | println!("{x} {y}", x, y);
+ | ^ ^
+help: this can be removed
+ |
+LL - println!("{x} {y}", x, y);
+LL + println!("{x} {y}", );
+ |
+
+error: redundant arguments
+ --> $DIR/issue-105225.rs:19:43
+ |
+LL | println!("{} {} {x} {y} {}", x, x, x, y, y);
+ | ^ ^
+ |
+note: the formatting specifiers are referencing the bindings already
+ --> $DIR/issue-105225.rs:19:26
+ |
+LL | println!("{} {} {x} {y} {}", x, x, x, y, y);
+ | ^
+help: this can be removed
+ |
+LL - println!("{} {} {x} {y} {}", x, x, x, y, y);
+LL + println!("{} {} {x} {y} {}", x, x, x, );
+ |
+
+error: aborting due to 5 previous errors
+