Rollup merge of #128110 - veera-sivarajan:bugfix-80173, r=cjgillot

Suggest Replacing Comma with Semicolon in Incorrect Repeat Expressions

Fixes #80173

This PR detects typos in repeat expressions like `["_", 10]` and `vec![String::new(), 10]` and suggests replacing comma with semicolon.

Also, improves code in other place by adding doc comments and making use of a helper function to check if a type implements `Clone`.

References:
1. For `vec![T; N]`: https://doc.rust-lang.org/std/macro.vec.html
2. For `[T; N]`: https://doc.rust-lang.org/std/primitive.array.html

2 files changed, 194 insertions, 0 deletions

diff --git a/tests/ui/repeat-expr/typo-in-repeat-expr-issue-80173.rs b/tests/ui/repeat-expr/typo-in-repeat-expr-issue-80173.rs
new file mode 100644
index 00000000000..c76e7a1d716
--- /dev/null
+++ b/tests/ui/repeat-expr/typo-in-repeat-expr-issue-80173.rs
@@ -0,0 +1,70 @@
+#[derive(Copy, Clone)]
+struct Type;
+
+struct NewType;
+
+const fn get_size() -> usize {
+    10
+}
+
+fn get_dyn_size() -> usize {
+    10
+}
+
+fn main() {
+    let a = ["a", 10];
+    //~^ ERROR mismatched types
+    //~| HELP replace the comma with a semicolon to create an array
+
+    const size_b: usize = 20;
+    let b = [Type, size_b];
+    //~^ ERROR mismatched types
+    //~| HELP replace the comma with a semicolon to create an array
+
+    let size_c: usize = 13;
+    let c = [Type, size_c];
+    //~^ ERROR mismatched types
+
+    const size_d: bool = true;
+    let d = [Type, size_d];
+    //~^ ERROR mismatched types
+
+    let e = [String::new(), 10];
+    //~^ ERROR mismatched types
+    //~| HELP try using a conversion method
+
+    let f = ["f", get_size()];
+    //~^ ERROR mismatched types
+    //~| HELP replace the comma with a semicolon to create an array
+
+    let m = ["m", get_dyn_size()];
+    //~^ ERROR mismatched types
+
+    // is_vec, is_clone, is_usize_like
+    let g = vec![String::new(), 10];
+    //~^ ERROR mismatched types
+    //~| HELP replace the comma with a semicolon to create a vector
+
+    let dyn_size = 10;
+    let h = vec![Type, dyn_size];
+    //~^ ERROR mismatched types
+    //~| HELP replace the comma with a semicolon to create a vector
+
+    let i = vec![Type, get_dyn_size()];
+    //~^ ERROR mismatched types
+    //~| HELP replace the comma with a semicolon to create a vector
+
+    let k = vec!['c', 10];
+    //~^ ERROR mismatched types
+    //~| HELP replace the comma with a semicolon to create a vector
+
+    let j = vec![Type, 10_u8];
+    //~^ ERROR mismatched types
+
+    let l = vec![NewType, 10];
+    //~^ ERROR mismatched types
+
+    let byte_size: u8 = 10;
+    let h = vec![Type, byte_size];
+    //~^ ERROR mismatched types
+}
diff --git a/tests/ui/repeat-expr/typo-in-repeat-expr-issue-80173.stderr b/tests/ui/repeat-expr/typo-in-repeat-expr-issue-80173.stderr
new file mode 100644
index 00000000000..95eddbde9e6
--- /dev/null
+++ b/tests/ui/repeat-expr/typo-in-repeat-expr-issue-80173.stderr
@@ -0,0 +1,124 @@
+error[E0308]: mismatched types
+  --> $DIR/typo-in-repeat-expr-issue-80173.rs:15:19
+   |
+LL |     let a = ["a", 10];
+   |                   ^^ expected `&str`, found integer
+   |
+help: replace the comma with a semicolon to create an array
+   |
+LL |     let a = ["a"; 10];
+   |                 ~
+
+error[E0308]: mismatched types
+  --> $DIR/typo-in-repeat-expr-issue-80173.rs:20:20
+   |
+LL |     let b = [Type, size_b];
+   |                    ^^^^^^ expected `Type`, found `usize`
+   |
+help: replace the comma with a semicolon to create an array
+   |
+LL |     let b = [Type; size_b];
+   |                  ~
+
+error[E0308]: mismatched types
+  --> $DIR/typo-in-repeat-expr-issue-80173.rs:25:20
+   |
+LL |     let c = [Type, size_c];
+   |                    ^^^^^^ expected `Type`, found `usize`
+
+error[E0308]: mismatched types
+  --> $DIR/typo-in-repeat-expr-issue-80173.rs:29:20
+   |
+LL |     let d = [Type, size_d];
+   |                    ^^^^^^ expected `Type`, found `bool`
+
+error[E0308]: mismatched types
+  --> $DIR/typo-in-repeat-expr-issue-80173.rs:32:29
+   |
+LL |     let e = [String::new(), 10];
+   |                             ^^- help: try using a conversion method: `.to_string()`
+   |                             |
+   |                             expected `String`, found integer
+
+error[E0308]: mismatched types
+  --> $DIR/typo-in-repeat-expr-issue-80173.rs:36:19
+   |
+LL |     let f = ["f", get_size()];
+   |                   ^^^^^^^^^^ expected `&str`, found `usize`
+   |
+help: replace the comma with a semicolon to create an array
+   |
+LL |     let f = ["f"; get_size()];
+   |                 ~
+
+error[E0308]: mismatched types
+  --> $DIR/typo-in-repeat-expr-issue-80173.rs:40:19
+   |
+LL |     let m = ["m", get_dyn_size()];
+   |                   ^^^^^^^^^^^^^^ expected `&str`, found `usize`
+
+error[E0308]: mismatched types
+  --> $DIR/typo-in-repeat-expr-issue-80173.rs:44:33
+   |
+LL |     let g = vec![String::new(), 10];
+   |                                 ^^ expected `String`, found integer
+   |
+help: replace the comma with a semicolon to create a vector
+   |
+LL |     let g = vec![String::new(); 10];
+   |                               ~
+
+error[E0308]: mismatched types
+  --> $DIR/typo-in-repeat-expr-issue-80173.rs:49:24
+   |
+LL |     let h = vec![Type, dyn_size];
+   |                        ^^^^^^^^ expected `Type`, found integer
+   |
+help: replace the comma with a semicolon to create a vector
+   |
+LL |     let h = vec![Type; dyn_size];
+   |                      ~
+
+error[E0308]: mismatched types
+  --> $DIR/typo-in-repeat-expr-issue-80173.rs:53:24
+   |
+LL |     let i = vec![Type, get_dyn_size()];
+   |                        ^^^^^^^^^^^^^^ expected `Type`, found `usize`
+   |
+help: replace the comma with a semicolon to create a vector
+   |
+LL |     let i = vec![Type; get_dyn_size()];
+   |                      ~
+
+error[E0308]: mismatched types
+  --> $DIR/typo-in-repeat-expr-issue-80173.rs:57:23
+   |
+LL |     let k = vec!['c', 10];
+   |                       ^^ expected `char`, found `u8`
+   |
+help: replace the comma with a semicolon to create a vector
+   |
+LL |     let k = vec!['c'; 10];
+   |                     ~
+
+error[E0308]: mismatched types
+  --> $DIR/typo-in-repeat-expr-issue-80173.rs:61:24
+   |
+LL |     let j = vec![Type, 10_u8];
+   |                        ^^^^^ expected `Type`, found `u8`
+
+error[E0308]: mismatched types
+  --> $DIR/typo-in-repeat-expr-issue-80173.rs:64:27
+   |
+LL |     let l = vec![NewType, 10];
+   |                           ^^ expected `NewType`, found integer
+
+error[E0308]: mismatched types
+  --> $DIR/typo-in-repeat-expr-issue-80173.rs:68:24
+   |
+LL |     let h = vec![Type, byte_size];
+   |                        ^^^^^^^^^ expected `Type`, found `u8`
+
+error: aborting due to 14 previous errors
+
+For more information about this error, try `rustc --explain E0308`.