From 8467ceff22477fe567883e6fbd810e0f9e220686 Mon Sep 17 00:00:00 2001 From: Esteban Küber Date: Wed, 23 Oct 2019 17:32:33 -0700 Subject: Tweak format string error to point at arguments always Add secondary span labels with no text to make it clear when there's a mismatch bewteen the positional arguments in a format string and the arguments to the macro. This shouldn't affect experienced users, but it should make it easier for newcomers to more clearly understand how `format!()` and `println!()` are supposed to be used. ``` error: 2 positional arguments in format string, but there is 1 argument --> file8.rs:2:14 | 2 | format!("{} {}", 1); | ^^ ^^ - ``` instead of ``` error: 2 positional arguments in format string, but there is 1 argument --> file8.rs:2:14 | 2 | format!("{} {}", 1); | ^^ ^^ ``` --- src/libsyntax_ext/format.rs | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) (limited to 'src/libsyntax_ext') diff --git a/src/libsyntax_ext/format.rs b/src/libsyntax_ext/format.rs index 45d9f79c28f..37310f46f7e 100644 --- a/src/libsyntax_ext/format.rs +++ b/src/libsyntax_ext/format.rs @@ -278,7 +278,7 @@ impl<'a, 'b> Context<'a, 'b> { /// format string. fn report_invalid_references(&self, numbered_position_args: bool) { let mut e; - let sp = if self.is_literal { + let sp = if self.is_literal { // Point at the formatting arguments. MultiSpan::from_spans(self.arg_spans.clone()) } else { MultiSpan::from_span(self.fmtsp) @@ -304,6 +304,9 @@ impl<'a, 'b> Context<'a, 'b> { self.describe_num_args(), ), ); + for arg in &self.args { // Point at the arguments that will be formatted. + e.span_label(arg.span, ""); + } } else { let (mut refs, spans): (Vec<_>, Vec<_>) = refs.unzip(); // Avoid `invalid reference to positional arguments 7 and 7 (there is 1 argument)` -- cgit 1.4.1-3-g733a5