https://github.com/golang/go/blob/master/src/cmd/compile/internal/gc/noder.go implements //line pragma parsing now that the old lexer has been replaced.

When splitting //line filename:line into the filename and line part, noder.go looks for the first ':' to make the split: See https://github.com/golang/go/blob/master/src/cmd/compile/internal/gc/noder.go, line 1025, strings.IndexByte.

This is a problem for filenames containing ':' such as in Windows (C:foo/bar.go) - the resulting line numbers will be incorrect (but no error is reported).

The old code looked for the last ':' after "// line ". See e.g., https://github.com/golang/go/blob/adda7ad29551d0880df1805ae22401551b1fbfa8/src/cmd/compile/internal/gc/lex.go, line 961ff., the last ':' position is recorded on line 987 and then used to split the string below (line 997).

This is a regression from 1.7 and should be fixed for 1.8 (fix is trivial).