From 97cf1c87bd98c13f4de91f7afbc971dba829ac92 Mon Sep 17 00:00:00 2001
From: sjwang05 <63834813+sjwang05@users.noreply.github.com>
Date: Fri, 27 Oct 2023 15:14:55 -0700
Subject: [PATCH] Suggest `=>` --> `>=` in conditions
---
.../rustc_parse/src/parser/diagnostics.rs | 20 ++++
compiler/rustc_parse/src/parser/expr.rs | 10 ++
tests/ui/missing/missing-block-hint.stderr | 4 +
tests/ui/parser/eq-gt-to-gt-eq.fixed | 45 ++++++++
tests/ui/parser/eq-gt-to-gt-eq.rs | 45 ++++++++
tests/ui/parser/eq-gt-to-gt-eq.stderr | 106 ++++++++++++++++++
6 files changed, 230 insertions(+)
create mode 100644 tests/ui/parser/eq-gt-to-gt-eq.fixed
create mode 100644 tests/ui/parser/eq-gt-to-gt-eq.rs
create mode 100644 tests/ui/parser/eq-gt-to-gt-eq.stderr
diff --git a/compiler/rustc_parse/src/parser/diagnostics.rs b/compiler/rustc_parse/src/parser/diagnostics.rs
index 2a8eb6edd23fd..8803b243aa852 100644
--- a/compiler/rustc_parse/src/parser/diagnostics.rs
+++ b/compiler/rustc_parse/src/parser/diagnostics.rs
@@ -610,6 +610,26 @@ impl<'a> Parser<'a> {
// FIXME: translation requires list formatting (for `expect`)
let mut err = self.struct_span_err(self.token.span, msg_exp);
+ // Look for usages of '=>' where '>=' was probably intended
+ if self.token == token::FatArrow
+ && expected
+ .iter()
+ .any(|tok| matches!(tok, TokenType::Operator | TokenType::Token(TokenKind::Le)))
+ && !expected.iter().any(|tok| {
+ matches!(
+ tok,
+ TokenType::Token(TokenKind::FatArrow) | TokenType::Token(TokenKind::Comma)
+ )
+ })
+ {
+ err.span_suggestion(
+ self.token.span,
+ "you might have meant to write a \"greater than or equal to\" comparison",
+ ">=",
+ Applicability::MaybeIncorrect,
+ );
+ }
+
if let TokenKind::Ident(symbol, _) = &self.prev_token.kind {
if ["def", "fun", "func", "function"].contains(&symbol.as_str()) {
err.span_suggestion_short(
diff --git a/compiler/rustc_parse/src/parser/expr.rs b/compiler/rustc_parse/src/parser/expr.rs
index 235b28b6e26e2..f6678298e5de1 100644
--- a/compiler/rustc_parse/src/parser/expr.rs
+++ b/compiler/rustc_parse/src/parser/expr.rs
@@ -2432,6 +2432,7 @@ impl<'a> Parser<'a> {
}
} else {
let attrs = self.parse_outer_attributes()?; // For recovery.
+ let maybe_fatarrow = self.token.clone();
let block = if self.check(&token::OpenDelim(Delimiter::Brace)) {
self.parse_block()?
} else {
@@ -2456,6 +2457,15 @@ impl<'a> Parser<'a> {
"you likely meant to continue parsing the let-chain starting here",
);
} else {
+ // Look for usages of '=>' where '>=' might be intended
+ if maybe_fatarrow.kind == token::FatArrow {
+ err.span_suggestion(
+ maybe_fatarrow.span,
+ "you might have meant to write a \"greater than or equal to\" comparison",
+ ">=",
+ Applicability::MaybeIncorrect,
+ );
+ }
err.span_note(
cond_span,
"the `if` expression is missing a block after this condition",
diff --git a/tests/ui/missing/missing-block-hint.stderr b/tests/ui/missing/missing-block-hint.stderr
index 16954223a4521..18719289abdc8 100644
--- a/tests/ui/missing/missing-block-hint.stderr
+++ b/tests/ui/missing/missing-block-hint.stderr
@@ -9,6 +9,10 @@ note: the `if` expression is missing a block after this condition
|
LL | if (foo) => {}
| ^^^^^
+help: you might have meant to write a "greater than or equal to" comparison
+ |
+LL | if (foo) >= {}
+ | ~~
error: expected `{`, found `bar`
--> $DIR/missing-block-hint.rs:7:13
diff --git a/tests/ui/parser/eq-gt-to-gt-eq.fixed b/tests/ui/parser/eq-gt-to-gt-eq.fixed
new file mode 100644
index 0000000000000..44cb464fc0c9c
--- /dev/null
+++ b/tests/ui/parser/eq-gt-to-gt-eq.fixed
@@ -0,0 +1,45 @@
+// run-rustfix
+// Check that we try to correct `=>` to `>=` in conditions.
+#![allow(unused)]
+
+fn main() {
+ let a = 0;
+ let b = 1;
+ if a >= b {} //~ERROR
+}
+
+fn foo() {
+ let a = 0;
+ if a >= 1 {} //~ERROR
+}
+
+fn a() {
+ let a = 0;
+ if 1 >= a {} //~ERROR
+}
+
+fn bar() {
+ let a = 0;
+ let b = 1;
+ if a >= b && a != b {} //~ERROR
+}
+
+fn qux() {
+ let a = 0;
+ let b = 1;
+ if a != b && a >= b {} //~ERROR
+}
+
+fn baz() {
+ let a = 0;
+ let b = 1;
+ let _ = a >= b; //~ERROR
+}
+
+fn b() {
+ let a = 0;
+ let b = 1;
+ match a >= b { //~ERROR
+ _ => todo!(),
+ }
+}
diff --git a/tests/ui/parser/eq-gt-to-gt-eq.rs b/tests/ui/parser/eq-gt-to-gt-eq.rs
new file mode 100644
index 0000000000000..dca67c89cc033
--- /dev/null
+++ b/tests/ui/parser/eq-gt-to-gt-eq.rs
@@ -0,0 +1,45 @@
+// run-rustfix
+// Check that we try to correct `=>` to `>=` in conditions.
+#![allow(unused)]
+
+fn main() {
+ let a = 0;
+ let b = 1;
+ if a => b {} //~ERROR
+}
+
+fn foo() {
+ let a = 0;
+ if a => 1 {} //~ERROR
+}
+
+fn a() {
+ let a = 0;
+ if 1 => a {} //~ERROR
+}
+
+fn bar() {
+ let a = 0;
+ let b = 1;
+ if a => b && a != b {} //~ERROR
+}
+
+fn qux() {
+ let a = 0;
+ let b = 1;
+ if a != b && a => b {} //~ERROR
+}
+
+fn baz() {
+ let a = 0;
+ let b = 1;
+ let _ = a => b; //~ERROR
+}
+
+fn b() {
+ let a = 0;
+ let b = 1;
+ match a => b { //~ERROR
+ _ => todo!(),
+ }
+}
diff --git a/tests/ui/parser/eq-gt-to-gt-eq.stderr b/tests/ui/parser/eq-gt-to-gt-eq.stderr
new file mode 100644
index 0000000000000..73f465f7b9b28
--- /dev/null
+++ b/tests/ui/parser/eq-gt-to-gt-eq.stderr
@@ -0,0 +1,106 @@
+error: expected `{`, found `=>`
+ --> $DIR/eq-gt-to-gt-eq.rs:8:10
+ |
+LL | if a => b {}
+ | ^^ expected `{`
+ |
+note: the `if` expression is missing a block after this condition
+ --> $DIR/eq-gt-to-gt-eq.rs:8:8
+ |
+LL | if a => b {}
+ | ^
+help: you might have meant to write a "greater than or equal to" comparison
+ |
+LL | if a >= b {}
+ | ~~
+
+error: expected `{`, found `=>`
+ --> $DIR/eq-gt-to-gt-eq.rs:13:10
+ |
+LL | if a => 1 {}
+ | ^^ expected `{`
+ |
+note: the `if` expression is missing a block after this condition
+ --> $DIR/eq-gt-to-gt-eq.rs:13:8
+ |
+LL | if a => 1 {}
+ | ^
+help: you might have meant to write a "greater than or equal to" comparison
+ |
+LL | if a >= 1 {}
+ | ~~
+
+error: expected `{`, found `=>`
+ --> $DIR/eq-gt-to-gt-eq.rs:18:10
+ |
+LL | if 1 => a {}
+ | ^^ expected `{`
+ |
+note: the `if` expression is missing a block after this condition
+ --> $DIR/eq-gt-to-gt-eq.rs:18:8
+ |
+LL | if 1 => a {}
+ | ^
+help: you might have meant to write a "greater than or equal to" comparison
+ |
+LL | if 1 >= a {}
+ | ~~
+
+error: expected `{`, found `=>`
+ --> $DIR/eq-gt-to-gt-eq.rs:24:10
+ |
+LL | if a => b && a != b {}
+ | ^^ expected `{`
+ |
+note: the `if` expression is missing a block after this condition
+ --> $DIR/eq-gt-to-gt-eq.rs:24:8
+ |
+LL | if a => b && a != b {}
+ | ^
+help: you might have meant to write a "greater than or equal to" comparison
+ |
+LL | if a >= b && a != b {}
+ | ~~
+
+error: expected `{`, found `=>`
+ --> $DIR/eq-gt-to-gt-eq.rs:30:20
+ |
+LL | if a != b && a => b {}
+ | ^^ expected `{`
+ |
+note: the `if` expression is missing a block after this condition
+ --> $DIR/eq-gt-to-gt-eq.rs:30:8
+ |
+LL | if a != b && a => b {}
+ | ^^^^^^^^^^^
+help: you might have meant to write a "greater than or equal to" comparison
+ |
+LL | if a != b && a >= b {}
+ | ~~
+
+error: expected one of `!`, `.`, `::`, `;`, `?`, `else`, `{`, or an operator, found `=>`
+ --> $DIR/eq-gt-to-gt-eq.rs:36:15
+ |
+LL | let _ = a => b;
+ | ^^ expected one of 8 possible tokens
+ |
+help: you might have meant to write a "greater than or equal to" comparison
+ |
+LL | let _ = a >= b;
+ | ~~
+
+error: expected one of `!`, `.`, `::`, `?`, `{`, or an operator, found `=>`
+ --> $DIR/eq-gt-to-gt-eq.rs:42:13
+ |
+LL | match a => b {
+ | ----- ^^ expected one of `!`, `.`, `::`, `?`, `{`, or an operator
+ | |
+ | while parsing this `match` expression
+ |
+help: you might have meant to write a "greater than or equal to" comparison
+ |
+LL | match a >= b {
+ | ~~
+
+error: aborting due to 7 previous errors
+