query!(..)/query_as!(..) strange behavior when inferring types for queries

[zshell31]

I have found these related issues/pull requests

I found only issues related to inferring types for nullable fields

• [query_as!] Incorrect nullability inferred on left join leading to a runtime exception #2127
• sqlx::query!(..) inferring wrong Option NULLable-types  #1852

Description

Let's say I have the following table in Postgres:

CREATE TABLE test (
id varchar(64) PRIMARY KEY,
name text NOT NULL
);

Also let's say I have three query options:

async fn sql1(session: &mut Transaction<'_, Postgres>) -> sqlx::Result<()> {
    let rows = sqlx::query!(r#"SELECT id AS "id: i64", name AS "name: i64" FROM test"#)
        .fetch_all(&mut **session)
        .await?;

    Ok(())
}

async fn sql2(session: &mut Transaction<'_, Postgres>) -> sqlx::Result<()> {
    struct Row {
        id: i64,
        name: i64,
    }
    let rows = sqlx::query_as!(Row, r#"SELECT id, name FROM test"#)
        .fetch_all(&mut **session)
        .await?;

    Ok(())
}

async fn sql3(session: &mut Transaction<'_, Postgres>) -> sqlx::Result<()> {
    struct Row {
        id: i64,
        name: i64,
    }

    let rows = sqlx::query_as!(
        Row,
        r#"SELECT id AS "id: i64", name AS "name: i64" FROM test"#
    )
    .fetch_all(&mut **session)
    .await?;

    Ok(())
}

Why does only option 2 fail?

  --> src/main.rs:16:16
   |
16 |     let rows = sqlx::query_as!(Row, r#"SELECT id, name FROM test"#)
   |                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `From<std::string::String>` is not implemented for `i64`, which is required by `std::string::String: Into<_>`
   |

At the same time, in documentation the following is written:

If you select a column foo as "foo: _" (Postgres/SQLite) or foo as `foo: _` (MySQL) it causes that column to be inferred based on the type of the corresponding field in the given record struct. Runtime type-checking is still done so an error will be emitted if the types are not compatible.

Reproduction steps

See code snippet in description

SQLx version

0.8.3

Enabled SQLx features

"runtime-tokio-rustls", "postgres"

Database server and version

Postgres 15.7

Operating system

Ubuntu 20.04

Rust version

1.84.1