cmd/compile: improve error message for "too few values in struct literal"

[smasher164]

Does this issue reproduce with the latest release?

Yes (tested on 1.18)

What did you do?

https://go.dev/play/p/2-Us-h1omW-

package main

type A struct {
	F1 int
	F2 bool
}

func main() {
	_ = A{0}
}

What did you expect to see?

./prog.go:9:9: too few values in struct literal for A

What did you see instead?

./prog.go:9:9: too few values in struct literal

Although the error message has a line:column, I found it tedious to locate the struct that was not initialized properly when there was a lot of nested structs, i.e.

A{B{},C{D{}}}

It would be helpful for the error message to specify the type name of the struct that wasn't initialized properly.

[mknyszek]

Which releases are you comparing output for?

CC @griesemer maybe?

[mknyszek]

Putting this in the 1.19 milestone optimistically.

[smasher164]

Which releases are you comparing output for?

Good point. I ran this on 1.18 (updated the description). On 1.17, I see the message

./prog.go:9:8: too few values in A{...}

which is much better.

[gopherbot]

Change https://go.dev/cl/394914 mentions this issue: go/types, types2: report struct type for literals with too few/many elements