Auto merge of #117934 - Young-Flash:dev, r=petrochenkov

feat: make `let_binding_suggestion` more reasonable

This is my first PR for rustc, which trying to fix https://github.com/rust-lang/rust/issues/117894, I am not familiar with some internal api so maybe some modification here isn't the way to go, appreciated for any review suggestion.

3 files changed, 50 insertions, 4 deletions

diff --git a/tests/ui/suggestions/suggest-let-for-assignment.fixed b/tests/ui/suggestions/suggest-let-for-assignment.fixed
index 3a25e25eede..76dc1dad80a 100644
--- a/tests/ui/suggestions/suggest-let-for-assignment.fixed
+++ b/tests/ui/suggestions/suggest-let-for-assignment.fixed
@@ -7,6 +7,12 @@ fn main() {
     let x = "x"; //~ ERROR cannot find value `x` in this scope
     println!("x: {}", x); //~ ERROR cannot find value `x` in this scope
 
+    let some_variable = 6; //~ cannot find value `let_some_variable` in this scope
+    println!("some_variable: {}", some_variable); //~ ERROR cannot find value `some_variable` in this scope
+
+    let other_variable = 6; //~ cannot find value `letother_variable` in this scope
+    println!("other_variable: {}", other_variable); //~ ERROR cannot find value `other_variable` in this scope
+
     if x == "x" {
         //~^ ERROR cannot find value `x` in this scope
         println!("x is 1");
diff --git a/tests/ui/suggestions/suggest-let-for-assignment.rs b/tests/ui/suggestions/suggest-let-for-assignment.rs
index 67705fe063a..f1edf65a726 100644
--- a/tests/ui/suggestions/suggest-let-for-assignment.rs
+++ b/tests/ui/suggestions/suggest-let-for-assignment.rs
@@ -7,6 +7,12 @@ fn main() {
     x = "x"; //~ ERROR cannot find value `x` in this scope
     println!("x: {}", x); //~ ERROR cannot find value `x` in this scope
 
+    let_some_variable = 6; //~ cannot find value `let_some_variable` in this scope
+    println!("some_variable: {}", some_variable); //~ ERROR cannot find value `some_variable` in this scope
+
+    letother_variable = 6; //~ cannot find value `letother_variable` in this scope
+    println!("other_variable: {}", other_variable); //~ ERROR cannot find value `other_variable` in this scope
+
     if x == "x" {
         //~^ ERROR cannot find value `x` in this scope
         println!("x is 1");
diff --git a/tests/ui/suggestions/suggest-let-for-assignment.stderr b/tests/ui/suggestions/suggest-let-for-assignment.stderr
index 3f6a3da4be2..8d97dbeb14a 100644
--- a/tests/ui/suggestions/suggest-let-for-assignment.stderr
+++ b/tests/ui/suggestions/suggest-let-for-assignment.stderr
@@ -32,14 +32,48 @@ error[E0425]: cannot find value `x` in this scope
 LL |     println!("x: {}", x);
    |                       ^ not found in this scope
 
+error[E0425]: cannot find value `let_some_variable` in this scope
+  --> $DIR/suggest-let-for-assignment.rs:10:5
+   |
+LL |     let_some_variable = 6;
+   |     ^^^^^^^^^^^^^^^^^
+   |
+help: you might have meant to introduce a new binding
+   |
+LL |     let some_variable = 6;
+   |     ~~~~~~~~~~~~~~~~~
+
+error[E0425]: cannot find value `some_variable` in this scope
+  --> $DIR/suggest-let-for-assignment.rs:11:35
+   |
+LL |     println!("some_variable: {}", some_variable);
+   |                                   ^^^^^^^^^^^^^ not found in this scope
+
+error[E0425]: cannot find value `letother_variable` in this scope
+  --> $DIR/suggest-let-for-assignment.rs:13:5
+   |
+LL |     letother_variable = 6;
+   |     ^^^^^^^^^^^^^^^^^
+   |
+help: you might have meant to introduce a new binding
+   |
+LL |     let other_variable = 6;
+   |     ~~~~~~~~~~~~~~~~~~
+
+error[E0425]: cannot find value `other_variable` in this scope
+  --> $DIR/suggest-let-for-assignment.rs:14:36
+   |
+LL |     println!("other_variable: {}", other_variable);
+   |                                    ^^^^^^^^^^^^^^ not found in this scope
+
 error[E0425]: cannot find value `x` in this scope
-  --> $DIR/suggest-let-for-assignment.rs:10:8
+  --> $DIR/suggest-let-for-assignment.rs:16:8
    |
 LL |     if x == "x" {
    |        ^ not found in this scope
 
 error[E0425]: cannot find value `y` in this scope
-  --> $DIR/suggest-let-for-assignment.rs:15:5
+  --> $DIR/suggest-let-for-assignment.rs:21:5
    |
 LL |     y = 1 + 2;
    |     ^
@@ -50,11 +84,11 @@ LL |     let y = 1 + 2;
    |     +++
 
 error[E0425]: cannot find value `y` in this scope
-  --> $DIR/suggest-let-for-assignment.rs:16:23
+  --> $DIR/suggest-let-for-assignment.rs:22:23
    |
 LL |     println!("y: {}", y);
    |                       ^ not found in this scope
 
-error: aborting due to 7 previous errors
+error: aborting due to 11 previous errors
 
 For more information about this error, try `rustc --explain E0425`.