fix issue-144595

[bb1yd]

relevant issue:#144595
I implement this issue by simply find every colon in the tuple struct.

This method has a problem that it might mislead the user when the user type something likestruct Foo(std::string:String); (accidentally type :: as :). The compiler will print:

help: if you wanted to create a tuple struct, remove field names:
 --> test.rs:3:21
  |
3 |     struct Foo(std::string:String);
  |                     -------

I'm not sure if this is acceptable. Maybe a better way is to parse the field as a record struct field again, but I don't know how to revert the parser to the beginning of the tuple field.

[rust-log-analyzer]

The job pr-check-2 failed! Check out the build log: (web) (plain enhanced) (plain)

Click to see the possible cause of the failure (guessed by this bot)

    Checking rustc_parse v0.0.0 (/checkout/compiler/rustc_parse)
error: this if-then-else expression returns a bool literal
    --> compiler/rustc_parse/src/parser/item.rs:2146:21
     |
2146 | /                     if t.kind == token::Colon || t.kind == token::Comma {
2147 | |                         false
2148 | |                     } else {
2149 | |                         true
2150 | |                     }
     | |_____________________^ help: you can reduce it to: `!(t.kind == token::Colon || t.kind == token::Comma)`
     |
     = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#needless_bool
     = note: requested on the command line with `-D clippy::needless-bool`

[RUSTC-TIMING] rustc_parse test:false 3.730