func defined1() int {
	// To check multiple errors for a single symbol,
	// reference undefined more than once.
	undefined()
	undefined()
	return 0
}

func defined2() {
	undefined()
	undefined()
}

func init() {
	_ = defined1()
	defined2()
}

        when:
        sourceFile << """
    #include "test1"
    #include "test2"
    #include <system1>
    #include <system2>
    #include DEFINED
    #include DEFINED2
    #include DEFINED()
    #include DEFINED2()
    #include DEFINED(ABC)
    #include DEFINED(X)
    #include DEFINED(X, Y)
    #include DEFINED(A, Y)
    #include not an include
"""
        then:
        includes == [

		// Single error reporting per each symbol.
		// This way, duplicated messages are not reported for
		// multiple relocations with a same name.
		"main.defined1: relocation target main.undefined not defined": 1,
		"main.defined2: relocation target main.undefined not defined": 1,
	}
	unexpectedErrors := map[string]int{}

	for _, l := range strings.Split(string(out), "\n") {
		if strings.HasPrefix(l, "#") || l == "" {
			continue
		}