Update description for error E0308

compiler/rustc_error_codes/src/error_codes/E0308.md

@@ -1,18 +1,26 @@
 Expected type did not match the received type.
 
-Erroneous code example:
+Erroneous code examples:
 
 ```compile_fail,E0308
-let x: i32 = "I am not a number!";
-//     ~~~   ~~~~~~~~~~~~~~~~~~~~
-//      |             |
-//      |    initializing expression;
-//      |    compiler infers type `&str`
-//      |
-//    type `i32` assigned to variable `x`
+fn plus_one(x: i32) -> i32 {
+    x + 1
+}
+
+plus_one("Not a number");
+//       ^^^^^^^^^^^^^^ expected `i32`, found `&str`
+
+if "Not a bool" {
+// ^^^^^^^^^^^^ expected `bool`, found `&str`
+}
+
+let x: f32 = "Not a float";
+//     ---   ^^^^^^^^^^^^^ expected `f32`, found `&str`
+//     |
+//     expected due to this
 ```
 
-This error occurs when the compiler is unable to infer the concrete type of a
-variable. It can occur in several cases, the most common being a mismatch
-between two types: the type the author explicitly assigned, and the type the
-compiler inferred.
+This error occurs when an expression was used in a place where the compiler
+expected an expression of a different type. It can occur in several cases, the
+most common being when calling a function and passing an argument which has a
+different type than the matching type in the function declaration.

src/test/ui/json-bom-plus-crlf-multifile.stderr

@@ -1,81 +1,113 @@
 {"message":"mismatched types","code":{"code":"E0308","explanation":"Expected type did not match the received type.
 
-Erroneous code example:
+Erroneous code examples:
 
 ```compile_fail,E0308
-let x: i32 = \"I am not a number!\";
-//     ~~~   ~~~~~~~~~~~~~~~~~~~~
-//      |             |
-//      |    initializing expression;
-//      |    compiler infers type `&str`
-//      |
-//    type `i32` assigned to variable `x`
+fn plus_one(x: i32) -> i32 {
+    x + 1
+}
+
+plus_one(\"Not a number\");
+//       ^^^^^^^^^^^^^^ expected `i32`, found `&str`
+
+if \"Not a bool\" {
+// ^^^^^^^^^^^^ expected `bool`, found `&str`
+}
+
+let x: f32 = \"Not a float\";
+//     ---   ^^^^^^^^^^^^^ expected `f32`, found `&str`
+//     |
+//     expected due to this
 ```
 
-This error occurs when the compiler is unable to infer the concrete type of a
-variable. It can occur in several cases, the most common being a mismatch
-between two types: the type the author explicitly assigned, and the type the
-compiler inferred.
+This error occurs when an expression was used in a place where the compiler
+expected an expression of a different type. It can occur in several cases, the
+most common being when calling a function and passing an argument which has a
+different type than the matching type in the function declaration.
 "},"level":"error","spans":[{"file_name":"$DIR/json-bom-plus-crlf-multifile-aux.rs","byte_start":621,"byte_end":622,"line_start":17,"line_end":17,"column_start":22,"column_end":23,"is_primary":true,"text":[{"text":"    let s : String = 1;  // Error in the middle of line.","highlight_start":22,"highlight_end":23}],"label":"expected struct `String`, found integer","suggested_replacement":null,"suggestion_applicability":null,"expansion":null},{"file_name":"$DIR/json-bom-plus-crlf-multifile-aux.rs","byte_start":612,"byte_end":618,"line_start":17,"line_end":17,"column_start":13,"column_end":19,"is_primary":false,"text":[{"text":"    let s : String = 1;  // Error in the middle of line.","highlight_start":13,"highlight_end":19}],"label":"expected due to this","suggested_replacement":null,"suggestion_applicability":null,"expansion":null}],"children":[{"message":"try using a conversion method","code":null,"level":"help","spans":[{"file_name":"$DIR/json-bom-plus-crlf-multifile-aux.rs","byte_start":621,"byte_end":622,"line_start":17,"line_end":17,"column_start":22,"column_end":23,"is_primary":true,"text":[{"text":"    let s : String = 1;  // Error in the middle of line.","highlight_start":22,"highlight_end":23}],"label":null,"suggested_replacement":"1.to_string()","suggestion_applicability":"MaybeIncorrect","expansion":null}],"children":[],"rendered":null}],"rendered":"$DIR/json-bom-plus-crlf-multifile-aux.rs:17:22: error[E0308]: mismatched types
 "}
 {"message":"mismatched types","code":{"code":"E0308","explanation":"Expected type did not match the received type.
 
-Erroneous code example:
+Erroneous code examples:
 
 ```compile_fail,E0308
-let x: i32 = \"I am not a number!\";
-//     ~~~   ~~~~~~~~~~~~~~~~~~~~
-//      |             |
-//      |    initializing expression;
-//      |    compiler infers type `&str`
-//      |
-//    type `i32` assigned to variable `x`
+fn plus_one(x: i32) -> i32 {
+    x + 1
+}
+
+plus_one(\"Not a number\");
+//       ^^^^^^^^^^^^^^ expected `i32`, found `&str`
+
+if \"Not a bool\" {
+// ^^^^^^^^^^^^ expected `bool`, found `&str`
+}
+
+let x: f32 = \"Not a float\";
+//     ---   ^^^^^^^^^^^^^ expected `f32`, found `&str`
+//     |
+//     expected due to this
 ```
 
-This error occurs when the compiler is unable to infer the concrete type of a
-variable. It can occur in several cases, the most common being a mismatch
-between two types: the type the author explicitly assigned, and the type the
-compiler inferred.
+This error occurs when an expression was used in a place where the compiler
+expected an expression of a different type. It can occur in several cases, the
+most common being when calling a function and passing an argument which has a
+different type than the matching type in the function declaration.
 "},"level":"error","spans":[{"file_name":"$DIR/json-bom-plus-crlf-multifile-aux.rs","byte_start":681,"byte_end":682,"line_start":19,"line_end":19,"column_start":22,"column_end":23,"is_primary":true,"text":[{"text":"    let s : String = 1","highlight_start":22,"highlight_end":23}],"label":"expected struct `String`, found integer","suggested_replacement":null,"suggestion_applicability":null,"expansion":null},{"file_name":"$DIR/json-bom-plus-crlf-multifile-aux.rs","byte_start":672,"byte_end":678,"line_start":19,"line_end":19,"column_start":13,"column_end":19,"is_primary":false,"text":[{"text":"    let s : String = 1","highlight_start":13,"highlight_end":19}],"label":"expected due to this","suggested_replacement":null,"suggestion_applicability":null,"expansion":null}],"children":[{"message":"try using a conversion method","code":null,"level":"help","spans":[{"file_name":"$DIR/json-bom-plus-crlf-multifile-aux.rs","byte_start":681,"byte_end":682,"line_start":19,"line_end":19,"column_start":22,"column_end":23,"is_primary":true,"text":[{"text":"    let s : String = 1","highlight_start":22,"highlight_end":23}],"label":null,"suggested_replacement":"1.to_string()","suggestion_applicability":"MaybeIncorrect","expansion":null}],"children":[],"rendered":null}],"rendered":"$DIR/json-bom-plus-crlf-multifile-aux.rs:19:22: error[E0308]: mismatched types
 "}
 {"message":"mismatched types","code":{"code":"E0308","explanation":"Expected type did not match the received type.
 
-Erroneous code example:
+Erroneous code examples:
 
 ```compile_fail,E0308
-let x: i32 = \"I am not a number!\";
-//     ~~~   ~~~~~~~~~~~~~~~~~~~~
-//      |             |
-//      |    initializing expression;
-//      |    compiler infers type `&str`
-//      |
-//    type `i32` assigned to variable `x`
+fn plus_one(x: i32) -> i32 {
+    x + 1
+}
+
+plus_one(\"Not a number\");
+//       ^^^^^^^^^^^^^^ expected `i32`, found `&str`
+
+if \"Not a bool\" {
+// ^^^^^^^^^^^^ expected `bool`, found `&str`
+}
+
+let x: f32 = \"Not a float\";
+//     ---   ^^^^^^^^^^^^^ expected `f32`, found `&str`
+//     |
+//     expected due to this
 ```
 
-This error occurs when the compiler is unable to infer the concrete type of a
-variable. It can occur in several cases, the most common being a mismatch
-between two types: the type the author explicitly assigned, and the type the
-compiler inferred.
+This error occurs when an expression was used in a place where the compiler
+expected an expression of a different type. It can occur in several cases, the
+most common being when calling a function and passing an argument which has a
+different type than the matching type in the function declaration.
 "},"level":"error","spans":[{"file_name":"$DIR/json-bom-plus-crlf-multifile-aux.rs","byte_start":745,"byte_end":746,"line_start":23,"line_end":23,"column_start":1,"column_end":2,"is_primary":true,"text":[{"text":"1;  // Error after the newline.","highlight_start":1,"highlight_end":2}],"label":"expected struct `String`, found integer","suggested_replacement":null,"suggestion_applicability":null,"expansion":null},{"file_name":"$DIR/json-bom-plus-crlf-multifile-aux.rs","byte_start":735,"byte_end":741,"line_start":22,"line_end":22,"column_start":13,"column_end":19,"is_primary":false,"text":[{"text":"    let s : String =","highlight_start":13,"highlight_end":19}],"label":"expected due to this","suggested_replacement":null,"suggestion_applicability":null,"expansion":null}],"children":[{"message":"try using a conversion method","code":null,"level":"help","spans":[{"file_name":"$DIR/json-bom-plus-crlf-multifile-aux.rs","byte_start":745,"byte_end":746,"line_start":23,"line_end":23,"column_start":1,"column_end":2,"is_primary":true,"text":[{"text":"1;  // Error after the newline.","highlight_start":1,"highlight_end":2}],"label":null,"suggested_replacement":"1.to_string()","suggestion_applicability":"MaybeIncorrect","expansion":null}],"children":[],"rendered":null}],"rendered":"$DIR/json-bom-plus-crlf-multifile-aux.rs:23:1: error[E0308]: mismatched types
 "}
 {"message":"mismatched types","code":{"code":"E0308","explanation":"Expected type did not match the received type.
 
-Erroneous code example:
+Erroneous code examples:
 
 ```compile_fail,E0308
-let x: i32 = \"I am not a number!\";
-//     ~~~   ~~~~~~~~~~~~~~~~~~~~
-//      |             |
-//      |    initializing expression;
-//      |    compiler infers type `&str`
-//      |
-//    type `i32` assigned to variable `x`
+fn plus_one(x: i32) -> i32 {
+    x + 1
+}
+
+plus_one(\"Not a number\");
+//       ^^^^^^^^^^^^^^ expected `i32`, found `&str`
+
+if \"Not a bool\" {
+// ^^^^^^^^^^^^ expected `bool`, found `&str`
+}
+
+let x: f32 = \"Not a float\";
+//     ---   ^^^^^^^^^^^^^ expected `f32`, found `&str`
+//     |
+//     expected due to this
 ```
 
-This error occurs when the compiler is unable to infer the concrete type of a
-variable. It can occur in several cases, the most common being a mismatch
-between two types: the type the author explicitly assigned, and the type the
-compiler inferred.
+This error occurs when an expression was used in a place where the compiler
+expected an expression of a different type. It can occur in several cases, the
+most common being when calling a function and passing an argument which has a
+different type than the matching type in the function declaration.
 "},"level":"error","spans":[{"file_name":"$DIR/json-bom-plus-crlf-multifile-aux.rs","byte_start":801,"byte_end":809,"line_start":25,"line_end":26,"column_start":22,"column_end":6,"is_primary":true,"text":[{"text":"    let s : String = (","highlight_start":22,"highlight_end":23},{"text":"    );  // Error spanning the newline.","highlight_start":1,"highlight_end":6}],"label":"expected struct `String`, found `()`","suggested_replacement":null,"suggestion_applicability":null,"expansion":null},{"file_name":"$DIR/json-bom-plus-crlf-multifile-aux.rs","byte_start":792,"byte_end":798,"line_start":25,"line_end":25,"column_start":13,"column_end":19,"is_primary":false,"text":[{"text":"    let s : String = (","highlight_start":13,"highlight_end":19}],"label":"expected due to this","suggested_replacement":null,"suggestion_applicability":null,"expansion":null}],"children":[],"rendered":"$DIR/json-bom-plus-crlf-multifile-aux.rs:25:22: error[E0308]: mismatched types
 "}
 {"message":"aborting due to 4 previous errors","code":null,"level":"error","spans":[],"children":[],"rendered":"error: aborting due to 4 previous errors