Tweak format string error to point at arguments always #65746

estebank · 2019-10-24T00:33:00Z

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);
  |              ^^ ^^

r? @Centril

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); | ^^ ^^ ```

Centril · 2019-10-24T00:41:11Z

src/libsyntax_ext/format.rs

@@ -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, "");


This use of "" is fairly weird but it works I suppose. :)

I know, but DiagnosticBuilder<'_> already handles "" conceptually as an Option::None so we might as well (ab)use it 🤷‍♂

Centril · 2019-10-24T00:41:42Z

@bors r+

bors · 2019-10-24T00:41:43Z

📌 Commit 8467cef has been approved by Centril

@Centril

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); | ^^ ^^ ``` r? @Centril

@Centril

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); | ^^ ^^ ``` r? @Centril

@ghost

Rollup of 8 pull requests Successful merges: - #65625 (Turn crate store into a resolver output) - #65627 (Forbid non-`structural_match` types in const generics) - #65710 (Update cargo) - #65729 (Update test cases for vxWorks) - #65746 (Tweak format string error to point at arguments always) - #65753 (Don't assert for different instance on impl trait alias) - #65755 (Avoid ICE when adjusting bad self ty) - #65766 (Update hashbrown to 0.6.2) Failed merges: r? @ghost

bors · 2019-10-25T04:17:22Z

☔ The latest upstream changes (presumably #65771) made this pull request unmergeable. Please resolve the merge conflicts.

rust-highfive assigned Centril Oct 24, 2019

rust-highfive added the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Oct 24, 2019

Centril reviewed Oct 24, 2019

View reviewed changes

bors added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Oct 24, 2019

Centril mentioned this pull request Oct 24, 2019

Rollup of 8 pull requests #65769

Closed

Centril mentioned this pull request Oct 24, 2019

Rollup of 8 pull requests #65771

Merged

bors merged commit 8467cef into rust-lang:master Oct 25, 2019

bors added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. and removed S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. labels Oct 25, 2019

estebank deleted the newcomer-format branch November 9, 2023 05:18

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Tweak format string error to point at arguments always #65746

Tweak format string error to point at arguments always #65746

estebank commented Oct 24, 2019

Centril Oct 24, 2019

estebank Oct 24, 2019

Centril commented Oct 24, 2019

bors commented Oct 24, 2019

bors commented Oct 25, 2019

Tweak format string error to point at arguments always #65746

Tweak format string error to point at arguments always #65746

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