Sometimes install Go version even when one exists

go/extractor/cli/go-autobuilder/go-autobuilder.go

@@ -737,12 +737,6 @@ func checkForUnsupportedVersions(v versionInfo) (msg, version string) {
 			"). Writing an environment file not specifying any version of Go."
 		version = ""
 		diagnostics.EmitUnsupportedVersionGoMod(msg)
-	} else if v.goEnvVersionFound && outsideSupportedRange(v.goEnvVersion) {
-		msg = "The version of Go installed in the environment (" + v.goEnvVersion +
-			") is outside of the supported range (" + minGoVersion + "-" + maxGoVersion +
-			"). Writing an environment file not specifying any version of Go."
-		version = ""
-		diagnostics.EmitUnsupportedVersionEnvironment(msg)
 	}
 
 	return msg, version
@@ -768,10 +762,20 @@ func checkForVersionsNotFound(v versionInfo) (msg, version string) {
 	}
 
 	if v.goEnvVersionFound && !v.goModVersionFound {
-		msg = "No `go.mod` file found. Version " + v.goEnvVersion + " installed in the " +
-			"environment. Writing an environment file not specifying any version of Go."
-		version = ""
-		diagnostics.EmitNoGoMod(msg)
+		if outsideSupportedRange(v.goEnvVersion) {
+			msg = "No `go.mod` file found. The version of Go installed in the environment (" +
+				v.goEnvVersion + ") is outside of the supported range (" + minGoVersion + "-" +
+				maxGoVersion + "). Writing an environment file specifying the maximum supported " +
+				"version of Go (" + maxGoVersion + ")."
+			version = maxGoVersion
+			diagnostics.EmitNoGoModAndGoEnvUnsupported(msg)
+		} else {
+			msg = "No `go.mod` file found. Version " + v.goEnvVersion + " installed in the " +
+				"environment is supported. Writing an environment file not specifying any " +
+				"version of Go."
+			version = ""
+			diagnostics.EmitNoGoModAndGoEnvSupported(msg)
+		}
 	}
 
 	return msg, version
@@ -789,10 +793,18 @@ func compareVersions(v versionInfo) (msg, version string) {
 			"file (" + v.goModVersion + ")."
 		version = v.goModVersion
 		diagnostics.EmitVersionGoModHigherVersionEnvironment(msg)
-	} else {
+	} else if outsideSupportedRange(v.goEnvVersion) {
 		msg = "The version of Go installed in the environment (" + v.goEnvVersion +
-			") is high enough for the version found in the `go.mod` file (" + v.goModVersion +
-			"). Writing an environment file not specifying any version of Go."
+			") is outside of the supported range (" + minGoVersion + "-" + maxGoVersion + "). " +
+			"Writing an environment file specifying the version of Go from the `go.mod` file (" +
+			v.goModVersion + ")."
+		version = v.goModVersion
+		diagnostics.EmitVersionGoModSupportedAndGoEnvUnsupported(msg)
+	} else {
+
+		msg = "The version of Go installed in the environment (" + v.goEnvVersion +
+			") is supported and is high enough for the version found in the `go.mod` file (" +
+			v.goModVersion + "). Writing an environment file not specifying any version of Go."
 		version = ""
 		diagnostics.EmitVersionGoModNotHigherVersionEnvironment(msg)
 	}

go/extractor/cli/go-autobuilder/go-autobuilder_test.go

@@ -49,13 +49,13 @@ func TestGetVersionToInstall(t *testing.T) {
 		{"9999.0", true, "1.1", true}:      "",
 		{"9999.0", true, "", false}:        "",
 		// Go installation found with version below minGoVersion
-		{"1.20", true, "1.2.2", true}: "",
-		{"1.11", true, "1.2.2", true}: "",
-		{"", false, "1.2.2", true}:    "",
+		{"1.20", true, "1.2.2", true}: "1.20",
+		{"1.11", true, "1.2.2", true}: "1.11",
+		{"", false, "1.2.2", true}:    maxGoVersion,
 		// Go installation found with version above maxGoVersion
-		{"1.20", true, "9999.0.1", true}: "",
-		{"1.11", true, "9999.0.1", true}: "",
-		{"", false, "9999.0.1", true}:    "",
+		{"1.20", true, "9999.0.1", true}: "1.20",
+		{"1.11", true, "9999.0.1", true}: "1.11",
+		{"", false, "9999.0.1", true}:    maxGoVersion,
 
 		// checkForVersionsNotFound()
 

go/extractor/diagnostics/diagnostics.go

@@ -205,17 +205,6 @@ func EmitUnsupportedVersionGoMod(msg string) {
 	)
 }
 
-func EmitUnsupportedVersionEnvironment(msg string) {
-	emitDiagnostic(
-		"go/autobuilder/env-unsupported-version-in-environment",
-		"Unsupported Go version in environment",
-		msg,
-		severityNote,
-		telemetryOnly,
-		noLocation,
-	)
-}
-
 func EmitNoGoModAndNoGoEnv(msg string) {
 	emitDiagnostic(
 		"go/autobuilder/env-no-go-mod-and-no-go-env",
@@ -238,10 +227,21 @@ func EmitNoGoEnv(msg string) {
 	)
 }
 
-func EmitNoGoMod(msg string) {
+func EmitNoGoModAndGoEnvUnsupported(msg string) {
 	emitDiagnostic(
-		"go/autobuilder/env-no-go-mod",
-		"No `go.mod` file found",
+		"go/autobuilder/env-no-go-mod-go-env-unsupported",
+		"No `go.mod` file found and Go version in environment is unsupported",
+		msg,
+		severityNote,
+		telemetryOnly,
+		noLocation,
+	)
+}
+
+func EmitNoGoModAndGoEnvSupported(msg string) {
+	emitDiagnostic(
+		"go/autobuilder/env-no-go-mod-go-env-supported",
+		"No `go.mod` file found and Go version in environment is supported",
 		msg,
 		severityNote,
 		telemetryOnly,
@@ -260,6 +260,17 @@ func EmitVersionGoModHigherVersionEnvironment(msg string) {
 	)
 }
 
+func EmitVersionGoModSupportedAndGoEnvUnsupported(msg string) {
+	emitDiagnostic(
+		"go/autobuilder/env-version-go-mod-higher-than-go-env",
+		"The Go version in `go.mod` file is higher than the Go version in environment",
+		msg,
+		severityNote,
+		telemetryOnly,
+		noLocation,
+	)
+}
+
 func EmitVersionGoModNotHigherVersionEnvironment(msg string) {
 	emitDiagnostic(
 		"go/autobuilder/env-version-go-mod-lower-than-or-equal-to-go-env",