[dev.cmdgo] cmd/go: maintain a go.work.sum file

This change causes the go command to maintain a separate go.work.sum
file when in workspace mode rather than using the go.sum files
from the individual modules. This isn't quite what the proposal
spec specifies, which is that the sums that don't exist in any
of the workspace modules are added to go.work.sum rather than
the necessary sums. That will be done in a future change.

Change-Id: I528b9b153a93a4cd67c5af471ad6d5bd3628578b
Reviewed-on: https://go-review.googlesource.com/c/go/+/334939
Trust: Michael Matloob <matloob@golang.org>
Run-TryBot: Michael Matloob <matloob@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Jay Conrod <jayconrod@google.com>

1 files changed, 20 insertions, 4 deletions

diff --git a/src/cmd/go/internal/modload/init.go b/src/cmd/go/internal/modload/init.go
index 3758786562..00dfc8b2dc 100644
--- a/src/cmd/go/internal/modload/init.go
+++ b/src/cmd/go/internal/modload/init.go
@@ -367,6 +367,7 @@ func Init() {
 		if err != nil {
 			base.Fatalf("reading go.work: %v", err)
 		}
+		modfetch.GoSumFile = workFilePath + ".sum"
 		// TODO(matloob) should workRoot just be workFile?
 	} else if modRoots == nil {
 		// We're in module mode, but not inside a module.
@@ -1009,6 +1010,10 @@ func setDefaultBuildMod() {
 	cfg.BuildMod = "readonly"
 }
 
+func mustHaveCompleteRequirements() bool {
+	return cfg.BuildMod != "mod" && !inWorkspaceMode()
+}
+
 // convertLegacyConfig imports module requirements from a legacy vendoring
 // configuration file, if one is present.
 func convertLegacyConfig(modFile *modfile.File, modPath string) (from string, err error) {
@@ -1306,10 +1311,17 @@ func commitRequirements(ctx context.Context, goVersion string, rs *Requirements)
 		return
 	}
 
+	if inWorkspaceMode() {
+		// go.mod files aren't updated in workspace mode, but we still want to
+		// update the go.work.sum file.
+		if err := modfetch.WriteGoSum(keepSums(ctx, loaded, rs, addBuildListZipSums), mustHaveCompleteRequirements()); err != nil {
+			base.Fatalf("go: %v", err)
+		}
+		return
+	}
+
 	if MainModules.Len() != 1 || MainModules.ModRoot(MainModules.Versions()[0]) == "" {
-		_ = TODOWorkspaces("also check that workspace mode is off")
 		// We aren't in a module, so we don't have anywhere to write a go.mod file.
-		_ = TODOWorkspaces("also check that workspace mode is off")
 		return
 	}
 	mainModule := MainModules.Versions()[0]
@@ -1346,7 +1358,9 @@ func commitRequirements(ctx context.Context, goVersion string, rs *Requirements)
 		// Don't write go.mod, but write go.sum in case we added or trimmed sums.
 		// 'go mod init' shouldn't write go.sum, since it will be incomplete.
 		if cfg.CmdName != "mod init" {
-			modfetch.WriteGoSum(keepSums(ctx, loaded, rs, addBuildListZipSums))
+			if err := modfetch.WriteGoSum(keepSums(ctx, loaded, rs, addBuildListZipSums), mustHaveCompleteRequirements()); err != nil {
+				base.Fatalf("go: %v", err)
+			}
 		}
 		return
 	}
@@ -1368,7 +1382,9 @@ func commitRequirements(ctx context.Context, goVersion string, rs *Requirements)
 		// Update go.sum after releasing the side lock and refreshing the index.
 		// 'go mod init' shouldn't write go.sum, since it will be incomplete.
 		if cfg.CmdName != "mod init" {
-			modfetch.WriteGoSum(keepSums(ctx, loaded, rs, addBuildListZipSums))
+			if err := modfetch.WriteGoSum(keepSums(ctx, loaded, rs, addBuildListZipSums), mustHaveCompleteRequirements()); err != nil {
+				base.Fatalf("go: %v", err)
+			}
 		}
 	}()