//
//	1.21 < 1.21rc1 < 1.21.0
//
// meaning that Go 1.21rc1 and Go 1.21.0 will both handle go.mod files that
// say "go 1.21", but Go 1.21rc1 will not handle files that say "go 1.21.0".
func IsLang(x string) bool {
	return gover.IsLang(x)
}

// Lang returns the Go language version. For example, Lang("1.2.3") == "1.2".
func Lang(x string) string {
	return gover.Lang(x)
}

var langTests = []testCase1[string, string]{
	{"1.2rc3", "1.2"},
	{"1.2.3", "1.2"},
	{"1.2", "1.2"},
	{"1", "1"},
	{"1.999testmod", "1.999"},
}

func TestIsLang(t *testing.T) { test1(t, isLangTests, "IsLang", IsLang) }

var isLangTests = []testCase1[string, bool]{
	{"1.2rc3", false},
	{"1.2.3", false},
	{"1.999testmod", false},
	{"1.22", true},
	{"1.21", true},
	{"1.20", false}, // == 1.20.0

var langTests = []testCase1[string, string]{
	{"1.2rc3", "1.2"},
	{"1.2.3", "1.2"},
	{"1.2", "1.2"},
	{"1", "1"},
	{"1.999testmod", "1.999"},
}

func TestIsLang(t *testing.T) { test1(t, isLangTests, "IsLang", IsLang) }

var isLangTests = []testCase1[string, bool]{
	{"1.2rc3", false},
	{"1.2.3", false},
	{"1.999testmod", false},
	{"1.22", true},
	{"1.21", true},
	{"1.20", false}, // == 1.20.0

// The caller is assumed to have checked that ModIsValid(path, vers) is true.
func ModIsPrefix(path, vers string) bool {
	if IsToolchain(path) {
		if path == "toolchain" {
			return IsLang(FromToolchain(vers))
		}
		return IsLang(vers)
	}
	// Semver
	dots := 0
	for i := 0; i < len(vers); i++ {
		switch vers[i] {
		case '-', '+':
			return false
		case '.':
			dots++
			if dots >= 2 {
				return false

// compared using Compare.
// If x and y compare equal, Max returns x.
func Max(x, y string) string {
	if Compare(x, y) < 0 {
		return y
	}
	return x
}

// IsLang reports whether v denotes the overall Go language version
// and not a specific release. Starting with the Go 1.21 release, "1.x" denotes
// the overall language version; the first release is "1.x.0".

	// we don't need to access the network to know that it exists.
	if r.path == "toolchain" && v == gover.Local() {
		return &RevInfo{Version: prefix + v}, nil
	}

	if gover.IsLang(v) {
		// We can only use a language (development) version if the current toolchain
		// implements that version, and the two checks above have ruled that out.

				// Don't try to download a language version (sans patch component), such as go1.22.
				// Instead, use the first toolchain of that language version, such as 1.22.0.
				// See golang.org/issue/62278.
				if gover.IsLang(goVers) && gover.Compare(goVers, "1.21") >= 0 {
					gotoolchain += ".0"
				}
				gover.Startup.AutoGoVersion = goVers
				gover.Startup.AutoToolchain = "" // in case we are overriding it for being too old
			}
		}

	// checking that the toolchain is new enough for the Go version.
	toolchain := "go" + old
	if wf.Toolchain != nil {
		toolchain = wf.Toolchain.Name
	}
	if gover.IsLang(gover.Local()) {
		toolchain = gover.ToolchainMax(toolchain, "go"+goVers)
	} else {
		toolchain = gover.ToolchainMax(toolchain, "go"+gover.Local())
	}

	// Drop the toolchain line if it is implied by the go line

						<la:message key="labels.searchoptions_all" />
					</c:if> <c:if test="${!empty lang}">
						<c:forEach var="sLang" items="${lang}">
							<c:forEach var="item" items="${langItems}">
								<c:if test="${item.value==sLang}">${f:h(item.label)}</c:if>
							</c:forEach>
						</c:forEach>
					</c:if>
			</a></li>
			<c:if test="${displayLabelTypeItems}">

						<la:message key="labels.searchoptions_all" />
					</c:if> <c:if test="${!empty lang}">
						<c:forEach var="sLang" items="${lang}">
							<c:forEach var="item" items="${langItems}">
								<c:if test="${item.value==sLang}">${f:h(item.label)}</c:if>
							</c:forEach>
						</c:forEach>
					</c:if>
			</a></li>
			<c:if test="${displayLabelTypeItems}">