Auto merge of #103636 - chenyukang:yukang/fix-103587-sugg-if-let, r=jackh276,davidtwco

Recover from common if let syntax mistakes/typos

Fixes #103587

2 files changed, 52 insertions, 0 deletions

diff --git a/src/test/ui/inference/issue-103587.rs b/src/test/ui/inference/issue-103587.rs
new file mode 100644
index 00000000000..11536f9f4cc
--- /dev/null
+++ b/src/test/ui/inference/issue-103587.rs
@@ -0,0 +1,12 @@
+fn main() {
+    let x = Some(123);
+
+    if let Some(_) == x {}
+    //~^ ERROR expected `=`, found `==`
+
+    if Some(_) = x {}
+    //~^ ERROR mismatched types
+
+    if None = x { }
+    //~^ ERROR mismatched types
+}
diff --git a/src/test/ui/inference/issue-103587.stderr b/src/test/ui/inference/issue-103587.stderr
new file mode 100644
index 00000000000..b373fbfbb94
--- /dev/null
+++ b/src/test/ui/inference/issue-103587.stderr
@@ -0,0 +1,40 @@
+error: expected `=`, found `==`
+  --> $DIR/issue-103587.rs:4:20
+   |
+LL |     if let Some(_) == x {}
+   |                    ^^
+   |
+help: consider using `=` here
+   |
+LL |     if let Some(_) = x {}
+   |                    ~
+
+error[E0308]: mismatched types
+  --> $DIR/issue-103587.rs:7:8
+   |
+LL |     if Some(_) = x {}
+   |        ^^^^^^^^^^^ expected `bool`, found `()`
+   |
+help: consider adding `let`
+   |
+LL |     if let Some(_) = x {}
+   |        +++
+
+error[E0308]: mismatched types
+  --> $DIR/issue-103587.rs:10:8
+   |
+LL |     if None = x { }
+   |        ^^^^^^^^ expected `bool`, found `()`
+   |
+help: you might have meant to use pattern matching
+   |
+LL |     if let None = x { }
+   |        +++
+help: you might have meant to compare for equality
+   |
+LL |     if None == x { }
+   |              +
+
+error: aborting due to 3 previous errors
+
+For more information about this error, try `rustc --explain E0308`.