Comment 1:

[The time for maybe has passed.]

Labels changed: removed go1.1maybe.

Comment 2:

Labels changed: added go1.2maybe.

Comment 3:

Labels changed: added go1.3maybe, removed go1.2maybe.

Comment 4:

Labels changed: added release-none, removed go1.3maybe.

Comment 5:

Labels changed: added repo-main.

I agree that it's a bit of a leap.

constant 0.9 truncated to integer

Compare that to the error when only variables are in the expression. It includes the expression and the types of the variables in question: https://play.golang.org/p/nfZ_xMultw

invalid operation: w * x (mismatched types float64 and int)

I like the idea of including (x) in the error message.

constant truncated: 0.9 * x ...

On the other hand, it's not always clear which variables are the cause when only variables are involved: https://play.golang.org/p/9_EchugdkA

invalid operation: v * w * x (mismatched types float64 and int)

So maybe there's a better way to do that error message as well. What comes to mind is the conversion syntax to indicate the types:

constant 0.9 truncated to integer: 0.9 * int(x)
mismatched types: float64(v) * float64(w) * int(x)

Here's a slightly more complex constants example where it might be nice if the error indicated that w is involved as well as that x is an integer (the reason for the truncation)

const w = 0.9
var x = 10
var z = w * w * x

constant 0.81 truncated to integer
constant 0.81 truncated to integer: w * w * int(x)
constant 0.81 truncated to integer: 0.9 * 0.9 * int(x)

https://play.golang.org/p/wklLBzn6XY

This is my random issue today via CodeTriage.

I suppose this is better now:

./prog.go:4:9: 0.9 (untyped float constant) truncated to int