cmd/go: remove loaderstate dependency

This change removes the dependency on the module loader state from the
`QueryMatchesMainModulesError.Error()` method.

This commit is part of the overall effort to eliminate global
modloader state.

Change-Id: I47241587a0bf9b578931628f35ed3b936a0cb04a
Reviewed-on: https://go-review.googlesource.com/c/go/+/714700
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Michael Matloob <matloob@google.com>
Reviewed-by: Michael Matloob <matloob@golang.org>

Author: jitsu-net

src/cmd/go/internal/modget/get.go

@@ -735,7 +735,12 @@ func (r *resolver) queryNone(loaderstate *modload.State, ctx context.Context, q
 				// However, neither of those behaviors would be consistent with the
 				// plain meaning of the query. To try to reduce confusion, reject the
 				// query explicitly.
-				return errSet(&modload.QueryMatchesMainModulesError{LoaderState: loaderstate, MainModules: []module.Version{v}, Pattern: q.pattern, Query: q.version})
+				return errSet(&modload.QueryMatchesMainModulesError{
+					MainModules:     []module.Version{v},
+					Pattern:         q.pattern,
+					Query:           q.version,
+					PatternIsModule: loaderstate.MainModules.Contains(q.pattern),
+				})
 			}
 
 			return pathSet{mod: module.Version{Path: q.pattern, Version: "none"}}
@@ -748,7 +753,12 @@ func (r *resolver) queryNone(loaderstate *modload.State, ctx context.Context, q
 		}
 		q.pathOnce(curM.Path, func() pathSet {
 			if modload.HasModRoot(loaderstate) && curM.Version == "" && loaderstate.MainModules.Contains(curM.Path) {
-				return errSet(&modload.QueryMatchesMainModulesError{LoaderState: loaderstate, MainModules: []module.Version{curM}, Pattern: q.pattern, Query: q.version})
+				return errSet(&modload.QueryMatchesMainModulesError{
+					MainModules:     []module.Version{curM},
+					Pattern:         q.pattern,
+					Query:           q.version,
+					PatternIsModule: loaderstate.MainModules.Contains(q.pattern),
+				})
 			}
 			return pathSet{mod: module.Version{Path: curM.Path, Version: "none"}}
 		})
@@ -852,10 +862,10 @@ func (r *resolver) queryWildcard(loaderstate *modload.State, ctx context.Context
 			if loaderstate.MainModules.Contains(curM.Path) && !versionOkForMainModule(q.version) {
 				if q.matchesPath(curM.Path) {
 					return errSet(&modload.QueryMatchesMainModulesError{
-						LoaderState: loaderstate,
-						MainModules: []module.Version{curM},
-						Pattern:     q.pattern,
-						Query:       q.version,
+						MainModules:     []module.Version{curM},
+						Pattern:         q.pattern,
+						Query:           q.version,
+						PatternIsModule: loaderstate.MainModules.Contains(q.pattern),
 					})
 				}
 
@@ -1953,10 +1963,10 @@ func (r *resolver) resolve(s *modload.State, q *query, m module.Version) {
 
 	if s.MainModules.Contains(m.Path) && m.Version != "" {
 		reportError(q, &modload.QueryMatchesMainModulesError{
-			LoaderState: s,
-			MainModules: []module.Version{{Path: m.Path}},
-			Pattern:     q.pattern,
-			Query:       q.version,
+			MainModules:     []module.Version{{Path: m.Path}},
+			Pattern:         q.pattern,
+			Query:           q.version,
+			PatternIsModule: s.MainModules.Contains(q.pattern),
 		})
 		return
 	}

src/cmd/go/internal/modload/query.go

@@ -763,10 +763,10 @@ func QueryPattern(loaderstate *State, ctx context.Context, pattern, query string
 			return nil, modOnly, nil
 		} else if len(mainModuleMatches) != 0 {
 			return nil, nil, &QueryMatchesMainModulesError{
-				LoaderState: loaderstate,
-				MainModules: mainModuleMatches,
-				Pattern:     pattern,
-				Query:       query,
+				MainModules:     mainModuleMatches,
+				Pattern:         pattern,
+				Query:           query,
+				PatternIsModule: loaderstate.MainModules.Contains(pattern),
 			}
 		} else {
 			return nil, nil, &PackageNotInModuleError{
@@ -827,9 +827,9 @@ func QueryPattern(loaderstate *State, ctx context.Context, pattern, query string
 
 	if len(mainModuleMatches) > 0 && len(results) == 0 && modOnly == nil && errors.Is(err, fs.ErrNotExist) {
 		return nil, nil, &QueryMatchesMainModulesError{
-			LoaderState: loaderstate,
-			Pattern:     pattern,
-			Query:       query,
+			Pattern:         pattern,
+			Query:           query,
+			PatternIsModule: loaderstate.MainModules.Contains(pattern),
 		}
 	}
 	return slices.Clip(results), modOnly, err
@@ -1287,15 +1287,14 @@ func (rr *replacementRepo) replacementStat(v string) (*modfetch.RevInfo, error)
 // a version of the main module that cannot be satisfied.
 // (The main module's version cannot be changed.)
 type QueryMatchesMainModulesError struct {
-	LoaderState *State
-	MainModules []module.Version
-	Pattern     string
-	Query       string
+	MainModules     []module.Version
+	Pattern         string
+	Query           string
+	PatternIsModule bool // true if pattern is one of the main modules
 }
 
 func (e *QueryMatchesMainModulesError) Error() string {
-	// TODO(jitsu): break dependency on loaderstate
-	if e.LoaderState.MainModules.Contains(e.Pattern) {
+	if e.PatternIsModule {
 		return fmt.Sprintf("can't request version %q of the main module (%s)", e.Query, e.Pattern)
 	}