The Go FAQ says:
the semicolons … are injected automatically … at the end of any line that could be the end of a statement.
it forces a brace style.
For instance, the opening brace of a function cannot appear on a line by itself.
It seems that Go will recognize func f() as a single statement.
However, when I run the following code:
package main
func f()
func main() { println(f) }
got missing function body.
Is there anything wrong with this? You’re defining a function and missing the body, which is wrong.
var f func()
Do you want to express function variables?
This question is about Go’s automatic semicolon insertion.
The error message indicated Go knows that func f() will followed by a {, so obviously ; shouldn’t be inserted at the end of func f() unless it can be a statement itself.
Exactly. Go knows that func f() is incomplete, and hence it does not recognize it as a statement and does not insert a semicolon.
But the FAQ indicates that a semicolon will be inserted at the end of func f() automatically thus
func f()
{ }
is incorrect.
A missing body is not necessarily wrong.
You can provide the implementation in an asm_*.s file
See https://go.dev/ref/spec#Function_declarations:
A function declaration without type parameters may omit the body. Such a declaration provides the signature for a function implemented outside Go, such as an assembly routine.
No, the FAQ states that Go inserts a semicolon if the end of the line could be the end a complete statement. The end of func f() cannot be the end of a complete statement by any definition, so Go does not insert a semicolon and errors out instead.
True, but you need to compile this in a special way: go tool compile -S <gofile.go>. See A Quick Guide to Go’s Assembler - The Go Programming Language
go tool compile -S <gofile.go> creates assembler from the gofile.go
To implement a function in assembler, it’s enough to have the implementation in asm_amd64.s (name depends on platform) in the directory where you call go build .
My fault. The assembly I used for testing was not correct, hence go build did not work for me.