Merge pull request #730 from owen-mc/bugfix/build/go-mod-tidy

Run `go mod tidy -e` before building

Author: smowton

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

@@ -2,7 +2,6 @@ package main
 
 import (
 	"fmt"
-	"golang.org/x/mod/semver"
 	"io/ioutil"
 	"log"
 	"net/url"
@@ -13,6 +12,8 @@ import (
 	"runtime"
 	"strings"
 
+	"golang.org/x/mod/semver"
+
 	"github.com/github/codeql-go/extractor/autobuilder"
 	"github.com/github/codeql-go/extractor/util"
 )
@@ -289,6 +290,44 @@ func main() {
 		}
 	}
 
+	// Go 1.16 and later won't automatically attempt to update go.mod / go.sum during package loading, so try to update them here:
+	if depMode == GoGetWithModules && semver.Compare(getEnvGoSemVer(), "1.16") >= 0 {
+		// stat go.mod and go.sum
+		beforeGoModFileInfo, beforeGoModErr := os.Stat("go.mod")
+		if beforeGoModErr != nil {
+			log.Println("Failed to stat go.mod before running `go mod tidy -e`")
+		}
+
+		beforeGoSumFileInfo, beforeGoSumErr := os.Stat("go.sum")
+
+		// run `go mod tidy -e`
+		res := util.RunCmd(exec.Command("go", "mod", "tidy", "-e"))
+
+		if !res {
+			log.Println("Failed to run `go mod tidy -e`")
+		} else {
+			if beforeGoModFileInfo != nil {
+				afterGoModFileInfo, afterGoModErr := os.Stat("go.mod")
+				if afterGoModErr != nil {
+					log.Println("Failed to stat go.mod after running `go mod tidy -e`")
+				} else if afterGoModFileInfo.ModTime().After(beforeGoModFileInfo.ModTime()) {
+					// if go.mod has been changed then notify the user
+					log.Println("We have run `go mod tidy -e` and it altered go.mod. You may wish to check these changes into version control. ")
+				}
+			}
+
+			afterGoSumFileInfo, afterGoSumErr := os.Stat("go.sum")
+			if afterGoSumErr != nil {
+				log.Println("Failed to stat go.sum after running `go mod tidy -e`")
+			} else {
+				if beforeGoSumErr != nil || afterGoSumFileInfo.ModTime().After(beforeGoSumFileInfo.ModTime()) {
+					// if go.sum has been changed then notify the user
+					log.Println("We have run `go mod tidy -e` and it altered go.sum. You may wish to check these changes into version control. ")
+				}
+			}
+		}
+	}
+
 	// if `LGTM_INDEX_NEED_GOPATH` is set, it overrides the value for `needGopath` inferred above
 	if needGopathOverride := os.Getenv("LGTM_INDEX_NEED_GOPATH"); needGopathOverride != "" {
 		inLGTM = true