Parse expression after `else` as a condition if followed by `{` #97298

compiler-errors · 2022-05-22T23:07:59Z

Fixes #49361.

Two things:

This wording needs help. I can never find a natural/intuitive phrasing when I write diagnostics 😅
Do we even want to show the "wrap in braces" case? I would assume most of the time the "add an if" case is the right one.

rust-highfive · 2022-05-22T23:08:02Z

r? @davidtwco

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davidtwco

One suggestion, otherwise looks good to me.

compiler/rustc_parse/src/parser/expr.rs

src/test/ui/parser/else-no-if.stderr

compiler-errors · 2022-05-24T04:10:32Z

@rustbot ready

davidtwco · 2022-05-24T07:31:28Z

@bors r+

bors · 2022-05-24T07:31:29Z

📌 Commit 9be37b2 has been approved by davidtwco

…, r=davidtwco Parse expression after `else` as a condition if followed by `{` Fixes rust-lang#49361. Two things: 1. This wording needs help. I can never find a natural/intuitive phrasing when I write diagnostics 😅 2. Do we even want to show the "wrap in braces" case? I would assume most of the time the "add an `if`" case is the right one.

Rollup of 4 pull requests Successful merges: - rust-lang#97288 (Lifetime variance fixes for rustdoc) - rust-lang#97298 (Parse expression after `else` as a condition if followed by `{`) - rust-lang#97308 (Stabilize `cell_filter_map`) - rust-lang#97321 (explain how to turn integers into fn ptrs) Failed merges: r? `@ghost` `@rustbot` modify labels: rollup

estebank · 2022-05-24T20:42:07Z

compiler/rustc_parse/src/parser/expr.rs

+                Ok(cond)
+                // If it's not a free-standing expression, and is followed by a block,
+                // then it's very likely the condition to an `else if`.
+                    if self.check(&TokenKind::OpenDelim(Delimiter::Brace))
+                        && classify::expr_requires_semi_to_be_stmt(&cond) =>
+                {


Given all the checks you have here...

estebank · 2022-05-24T20:42:22Z

compiler/rustc_parse/src/parser/expr.rs

+                        ).multipart_suggestion(
+                            "... otherwise, place this expression inside of a block if it is not an `if` condition",
+                            vec![
+                                (cond.span.shrink_to_lo(), "{ ".to_string()),
+                                (cond.span.shrink_to_hi(), " }".to_string()),
+                            ],
+                            Applicability::MaybeIncorrect,
+                        )


...I would have likely skipped this suggestion :)

neoeinstein · 2022-05-25T00:31:47Z

compiler/rustc_parse/src/parser/expr.rs

+                        .span_label(else_span, "expected an `if` or a block after this `else`")
+                        .span_suggestion(
+                            cond.span.shrink_to_lo(),
+                            "add an `if` if this is the condition to an chained `if` statement after the `else`",


Suggested change

"add an `if` if this is the condition to an chained `if` statement after the `else`",

"add an `if` if this is the condition to a chained `if` statement after the `else`",

#97370 addresses this suggestion and @estebank's above.

…an-DPC Minor improvement on else-no-if diagnostic Don't suggest wrapping in block since it's highly likely to be a missing `if` after `else`. Also rework message a bit (open to further suggestions). cc: rust-lang#97298 (comment) r? `@estebank`

rust-highfive assigned davidtwco May 22, 2022

rustbot added the T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. label May 22, 2022

rust-highfive added the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label May 22, 2022

davidtwco requested changes May 23, 2022

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davidtwco 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-review Status: Awaiting review from the assignee but also interested parties. labels May 23, 2022

fmease reviewed May 23, 2022

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Parse expression after else as a condition if followed by {

9be37b2

compiler-errors force-pushed the if-else-stmt-braces branch from 0246585 to 9be37b2 Compare May 24, 2022 04:10

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. and removed S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels May 24, 2022

davidtwco approved these changes May 24, 2022

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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 May 24, 2022

Dylan-DPC mentioned this pull request May 24, 2022

Rollup of 5 pull requests #97347

Closed

Dylan-DPC mentioned this pull request May 24, 2022

Rollup of 4 pull requests #97349

Closed

Dylan-DPC mentioned this pull request May 24, 2022

Rollup of 4 pull requests #97356

Merged

bors merged commit 0531521 into rust-lang:master May 24, 2022

rustbot added this to the 1.63.0 milestone May 24, 2022

estebank reviewed May 24, 2022

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compiler-errors mentioned this pull request May 24, 2022

Minor improvement on else-no-if diagnostic #97370

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neoeinstein reviewed May 25, 2022

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compiler-errors deleted the if-else-stmt-braces branch August 11, 2023 20:02

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Parse expression after `else` as a condition if followed by `{` #97298

Parse expression after `else` as a condition if followed by `{` #97298

compiler-errors commented May 22, 2022 •

edited

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rust-highfive commented May 22, 2022

davidtwco left a comment

compiler-errors commented May 24, 2022

davidtwco commented May 24, 2022

bors commented May 24, 2022

estebank May 24, 2022

estebank May 24, 2022

neoeinstein May 25, 2022

compiler-errors May 25, 2022

	"add an `if` if this is the condition to an chained `if` statement after the `else`",
	"add an `if` if this is the condition to a chained `if` statement after the `else`",

Parse expression after else as a condition if followed by { #97298

Parse expression after else as a condition if followed by { #97298

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Parse expression after `else` as a condition if followed by `{` #97298

Parse expression after `else` as a condition if followed by `{` #97298

compiler-errors commented May 22, 2022 •

edited

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