The basic syntax of Go is C-like (this is not intended to be controversial), including that of comments. There is also a C syntax for communicating with the compiler: #pragma. There is no need for yet another syntax here. Just follow the example set by the language that has already heavily influenced the Go syntax.

Note that C compilers already have the attributes people are demanding here: pragma directives are parsed, unknown pragmas generate errors or warnings, they are both visually and syntactically distinct from comments (intended for humans, not the toolchain), etc.

Solved problem. There's no reason to invent new syntax here.