commands: Improve the common build flag handling

Updates #10947

16 files changed, 86 insertions, 71 deletions

diff --git a/commands/commandeer.go b/commands/commandeer.go
index 7e5318996..e433e935a 100644
--- a/commands/commandeer.go
+++ b/commands/commandeer.go
@@ -111,22 +111,6 @@ type rootCommand struct {
 	environment string
 
 	// Common build flags.
-	*buildFlags
-
-	// TODO(bep) var vs string
-	logging        bool
-	verbose        bool
-	verboseLog     bool
-	debug          bool
-	quiet          bool
-	renderToMemory bool
-
-	cfgFile string
-	cfgDir  string
-	logFile string
-}
-
-type buildFlags struct {
 	baseURL         string
 	gc              bool
 	poll            string
@@ -139,6 +123,18 @@ type buildFlags struct {
 	mutexprofile string
 	traceprofile string
 	printm       bool
+
+	// TODO(bep) var vs string
+	logging        bool
+	verbose        bool
+	verboseLog     bool
+	debug          bool
+	quiet          bool
+	renderToMemory bool
+
+	cfgFile string
+	cfgDir  string
+	logFile string
 }
 
 func (r *rootCommand) Build(cd *simplecobra.Commandeer, bcfg hugolib.BuildCfg, cfg config.Provider) (*hugolib.HugoSites, error) {
@@ -384,7 +380,7 @@ func (r *rootCommand) Run(ctx context.Context, cd *simplecobra.Commandeer, args
 	return nil
 }
 
-func (r *rootCommand) Init(cd, runner *simplecobra.Commandeer) error {
+func (r *rootCommand) PreRun(cd, runner *simplecobra.Commandeer) error {
 	r.Out = os.Stdout
 	if r.quiet {
 		r.Out = io.Discard
@@ -463,7 +459,8 @@ func (r *rootCommand) IsTestRun() bool {
 	return os.Getenv("HUGO_TESTRUN") != ""
 }
 
-func (r *rootCommand) WithCobraCommand(cmd *cobra.Command) error {
+func (r *rootCommand) Init(cd *simplecobra.Commandeer) error {
+	cmd := cd.CobraCommand
 	cmd.Use = "hugo [flags]"
 	cmd.Short = "hugo builds your site"
 	cmd.Long = `hugo is the main command, used to build your Hugo site.
@@ -503,7 +500,7 @@ Complete documentation is available at https://gohugo.io/.`
 	_ = cmd.PersistentFlags().SetAnnotation("logFile", cobra.BashCompFilenameExt, []string{})
 
 	// Configure local flags
-	applyLocalBuildFlags(cmd, r.buildFlags)
+	applyLocalBuildFlags(cmd, r)
 
 	// Set bash-completion.
 	// Each flag must first be defined before using the SetAnnotation() call.
@@ -512,7 +509,7 @@ Complete documentation is available at https://gohugo.io/.`
 	return nil
 }
 
-func applyLocalBuildFlags(cmd *cobra.Command, f *buildFlags) {
+func applyLocalBuildFlags(cmd *cobra.Command, r *rootCommand) {
 	cmd.Flags().Bool("cleanDestinationDir", false, "remove files from destination not found in static directories")
 	cmd.Flags().BoolP("buildDrafts", "D", false, "include content marked as draft")
 	cmd.Flags().BoolP("buildFuture", "F", false, "include content with publishdate in the future")
@@ -522,25 +519,25 @@ func applyLocalBuildFlags(cmd *cobra.Command, f *buildFlags) {
 	cmd.Flags().StringP("cacheDir", "", "", "filesystem path to cache directory. Defaults: $TMPDIR/hugo_cache/")
 	cmd.Flags().BoolP("ignoreCache", "", false, "ignores the cache directory")
 	cmd.Flags().StringSliceP("theme", "t", []string{}, "themes to use (located in /themes/THEMENAME/)")
-	cmd.Flags().StringVarP(&f.baseURL, "baseURL", "b", "", "hostname (and path) to the root, e.g. https://spf13.com/")
+	cmd.Flags().StringVarP(&r.baseURL, "baseURL", "b", "", "hostname (and path) to the root, e.g. https://spf13.com/")
 	cmd.Flags().Bool("enableGitInfo", false, "add Git revision, date, author, and CODEOWNERS info to the pages")
-	cmd.Flags().BoolVar(&f.gc, "gc", false, "enable to run some cleanup tasks (remove unused cache files) after the build")
-	cmd.Flags().StringVar(&f.poll, "poll", "", "set this to a poll interval, e.g --poll 700ms, to use a poll based approach to watch for file system changes")
-	cmd.Flags().BoolVar(&f.panicOnWarning, "panicOnWarning", false, "panic on first WARNING log")
+	cmd.Flags().BoolVar(&r.gc, "gc", false, "enable to run some cleanup tasks (remove unused cache files) after the build")
+	cmd.Flags().StringVar(&r.poll, "poll", "", "set this to a poll interval, e.g --poll 700ms, to use a poll based approach to watch for file system changes")
+	cmd.Flags().BoolVar(&r.panicOnWarning, "panicOnWarning", false, "panic on first WARNING log")
 	cmd.Flags().Bool("templateMetrics", false, "display metrics about template executions")
 	cmd.Flags().Bool("templateMetricsHints", false, "calculate some improvement hints when combined with --templateMetrics")
-	cmd.Flags().BoolVar(&f.forceSyncStatic, "forceSyncStatic", false, "copy all files when static is changed.")
+	cmd.Flags().BoolVar(&r.forceSyncStatic, "forceSyncStatic", false, "copy all files when static is changed.")
 	cmd.Flags().BoolP("noTimes", "", false, "don't sync modification time of files")
 	cmd.Flags().BoolP("noChmod", "", false, "don't sync permission mode of files")
 	cmd.Flags().BoolP("noBuildLock", "", false, "don't create .hugo_build.lock file")
 	cmd.Flags().BoolP("printI18nWarnings", "", false, "print missing translations")
 	cmd.Flags().BoolP("printPathWarnings", "", false, "print warnings on duplicate target paths etc.")
 	cmd.Flags().BoolP("printUnusedTemplates", "", false, "print warnings on unused templates.")
-	cmd.Flags().StringVarP(&f.cpuprofile, "profile-cpu", "", "", "write cpu profile to `file`")
-	cmd.Flags().StringVarP(&f.memprofile, "profile-mem", "", "", "write memory profile to `file`")
-	cmd.Flags().BoolVarP(&f.printm, "printMemoryUsage", "", false, "print memory usage to screen at intervals")
-	cmd.Flags().StringVarP(&f.mutexprofile, "profile-mutex", "", "", "write Mutex profile to `file`")
-	cmd.Flags().StringVarP(&f.traceprofile, "trace", "", "", "write trace to `file` (not useful in general)")
+	cmd.Flags().StringVarP(&r.cpuprofile, "profile-cpu", "", "", "write cpu profile to `file`")
+	cmd.Flags().StringVarP(&r.memprofile, "profile-mem", "", "", "write memory profile to `file`")
+	cmd.Flags().BoolVarP(&r.printm, "printMemoryUsage", "", false, "print memory usage to screen at intervals")
+	cmd.Flags().StringVarP(&r.mutexprofile, "profile-mutex", "", "", "write Mutex profile to `file`")
+	cmd.Flags().StringVarP(&r.traceprofile, "trace", "", "", "write trace to `file` (not useful in general)")
 
 	// Hide these for now.
 	cmd.Flags().MarkHidden("profile-cpu")
@@ -591,7 +588,8 @@ func (c *simpleCommand) Run(ctx context.Context, cd *simplecobra.Commandeer, arg
 	return c.run(ctx, cd, c.rootCmd, args)
 }
 
-func (c *simpleCommand) WithCobraCommand(cmd *cobra.Command) error {
+func (c *simpleCommand) Init(cd *simplecobra.Commandeer) error {
+	cmd := cd.CobraCommand
 	cmd.Short = c.short
 	cmd.Long = c.long
 	if c.use != "" {
@@ -603,7 +601,7 @@ func (c *simpleCommand) WithCobraCommand(cmd *cobra.Command) error {
 	return nil
 }
 
-func (c *simpleCommand) Init(cd, runner *simplecobra.Commandeer) error {
+func (c *simpleCommand) PreRun(cd, runner *simplecobra.Commandeer) error {
 	c.rootCmd = cd.Root.Command.(*rootCommand)
 	if c.initc != nil {
 		return c.initc(cd)
diff --git a/commands/commands.go b/commands/commands.go
index f90b09e0c..9d707b841 100644
--- a/commands/commands.go
+++ b/commands/commands.go
@@ -20,7 +20,6 @@ import (
 // newExec wires up all of Hugo's CLI.
 func newExec() (*simplecobra.Exec, error) {
 	rootCmd := &rootCommand{
-		buildFlags: &buildFlags{},
 		commands: []simplecobra.Commander{
 			newVersionCmd(),
 			newEnvCommand(),
diff --git a/commands/config.go b/commands/config.go
index 6f0a29b35..80b869a28 100644
--- a/commands/config.go
+++ b/commands/config.go
@@ -23,7 +23,6 @@ import (
 	"github.com/gohugoio/hugo/modules"
 	"github.com/gohugoio/hugo/parser"
 	"github.com/gohugoio/hugo/parser/metadecoders"
-	"github.com/spf13/cobra"
 )
 
 // newConfigCommand creates a new config command and its subcommands.
@@ -68,13 +67,14 @@ func (c *configCommand) Run(ctx context.Context, cd *simplecobra.Commandeer, arg
 	return nil
 }
 
-func (c *configCommand) WithCobraCommand(cmd *cobra.Command) error {
+func (c *configCommand) Init(cd *simplecobra.Commandeer) error {
+	cmd := cd.CobraCommand
 	cmd.Short = "Print the site configuration"
 	cmd.Long = `Print the site configuration, both default and custom settings.`
 	return nil
 }
 
-func (c *configCommand) Init(cd, runner *simplecobra.Commandeer) error {
+func (c *configCommand) PreRun(cd, runner *simplecobra.Commandeer) error {
 	c.r = cd.Root.Command.(*rootCommand)
 	return nil
 }
@@ -176,12 +176,13 @@ func (c *configMountsCommand) Run(ctx context.Context, cd *simplecobra.Commandee
 	return nil
 }
 
-func (c *configMountsCommand) WithCobraCommand(cmd *cobra.Command) error {
+func (c *configMountsCommand) Init(cd *simplecobra.Commandeer) error {
+	cmd := cd.CobraCommand
 	cmd.Short = "Print the configured file mounts"
 	return nil
 }
 
-func (c *configMountsCommand) Init(cd, runner *simplecobra.Commandeer) error {
+func (c *configMountsCommand) PreRun(cd, runner *simplecobra.Commandeer) error {
 	c.configCmd = cd.Parent.Command.(*configCommand)
 	return nil
 }
diff --git a/commands/convert.go b/commands/convert.go
index 0cae5ad7e..e5c367913 100644
--- a/commands/convert.go
+++ b/commands/convert.go
@@ -100,7 +100,8 @@ func (c *convertCommand) Run(ctx context.Context, cd *simplecobra.Commandeer, ar
 	return nil
 }
 
-func (c *convertCommand) WithCobraCommand(cmd *cobra.Command) error {
+func (c *convertCommand) Init(cd *simplecobra.Commandeer) error {
+	cmd := cd.CobraCommand
 	cmd.Short = "Convert your content to different formats"
 	cmd.Long = `Convert your content (e.g. front matter) to different formats.
 
@@ -112,7 +113,7 @@ See convert's subcommands toJSON, toTOML and toYAML for more information.`
 	return nil
 }
 
-func (c *convertCommand) Init(cd, runner *simplecobra.Commandeer) error {
+func (c *convertCommand) PreRun(cd, runner *simplecobra.Commandeer) error {
 	c.r = cd.Root.Command.(*rootCommand)
 	cfg := config.New()
 	cfg.Set("buildDrafts", true)
diff --git a/commands/gen.go b/commands/gen.go
index 7ff75372a..fde5ae3bc 100644
--- a/commands/gen.go
+++ b/commands/gen.go
@@ -202,12 +202,13 @@ func (c *genCommand) Run(ctx context.Context, cd *simplecobra.Commandeer, args [
 	return nil
 }
 
-func (c *genCommand) WithCobraCommand(cmd *cobra.Command) error {
+func (c *genCommand) Init(cd *simplecobra.Commandeer) error {
+	cmd := cd.CobraCommand
 	cmd.Short = "A collection of several useful generators."
 	return nil
 }
 
-func (c *genCommand) Init(cd, runner *simplecobra.Commandeer) error {
+func (c *genCommand) PreRun(cd, runner *simplecobra.Commandeer) error {
 	c.rootCmd = cd.Root.Command.(*rootCommand)
 	return nil
 }
diff --git a/commands/import.go b/commands/import.go
index 20d23dfac..258323a3a 100644
--- a/commands/import.go
+++ b/commands/import.go
@@ -90,7 +90,8 @@ func (c *importCommand) Run(ctx context.Context, cd *simplecobra.Commandeer, arg
 	return nil
 }
 
-func (c *importCommand) WithCobraCommand(cmd *cobra.Command) error {
+func (c *importCommand) Init(cd *simplecobra.Commandeer) error {
+	cmd := cd.CobraCommand
 	cmd.Short = "Import your site from others."
 	cmd.Long = `Import your site from other web site generators like Jekyll.
 
@@ -99,7 +100,7 @@ Import requires a subcommand, e.g. ` + "`hugo import jekyll jekyll_root_path tar
 	return nil
 }
 
-func (c *importCommand) Init(cd, runner *simplecobra.Commandeer) error {
+func (c *importCommand) PreRun(cd, runner *simplecobra.Commandeer) error {
 	c.r = cd.Root.Command.(*rootCommand)
 	return nil
 }
diff --git a/commands/list.go b/commands/list.go
index 2f2e29887..1ce45987b 100644
--- a/commands/list.go
+++ b/commands/list.go
@@ -23,7 +23,6 @@ import (
 	"github.com/gohugoio/hugo/hugolib"
 	"github.com/gohugoio/hugo/resources/page"
 	"github.com/gohugoio/hugo/resources/resource"
-	"github.com/spf13/cobra"
 )
 
 // newListCommand creates a new list command and its subcommands.
@@ -153,7 +152,8 @@ func (c *listCommand) Run(ctx context.Context, cd *simplecobra.Commandeer, args
 	return nil
 }
 
-func (c *listCommand) WithCobraCommand(cmd *cobra.Command) error {
+func (c *listCommand) Init(cd *simplecobra.Commandeer) error {
+	cmd := cd.CobraCommand
 	cmd.Short = "Listing out various types of content"
 	cmd.Long = `Listing out various types of content.
 
@@ -162,6 +162,6 @@ List requires a subcommand, e.g. hugo list drafts`
 	return nil
 }
 
-func (c *listCommand) Init(cd, runner *simplecobra.Commandeer) error {
+func (c *listCommand) PreRun(cd, runner *simplecobra.Commandeer) error {
 	return nil
 }
diff --git a/commands/mod.go b/commands/mod.go
index a0e488ecd..1af1f7431 100644
--- a/commands/mod.go
+++ b/commands/mod.go
@@ -293,7 +293,8 @@ func (c *modCommands) Run(ctx context.Context, cd *simplecobra.Commandeer, args
 	return nil
 }
 
-func (c *modCommands) WithCobraCommand(cmd *cobra.Command) error {
+func (c *modCommands) Init(cd *simplecobra.Commandeer) error {
+	cmd := cd.CobraCommand
 	cmd.Short = "Various Hugo Modules helpers."
 	cmd.Long = `Various helpers to help manage the modules in your project's dependency graph.
 Most operations here requires a Go version installed on your system (>= Go 1.12) and the relevant VCS client (typically Git).
@@ -304,7 +305,7 @@ This is not needed if you only operate on modules inside /themes or if you have
 	return nil
 }
 
-func (c *modCommands) Init(cd, runner *simplecobra.Commandeer) error {
+func (c *modCommands) PreRun(cd, runner *simplecobra.Commandeer) error {
 	c.r = cd.Root.Command.(*rootCommand)
 	return nil
 }
diff --git a/commands/new.go b/commands/new.go
index 3a0e3ad71..5a940a1cd 100644
--- a/commands/new.go
+++ b/commands/new.go
@@ -271,7 +271,8 @@ func (c *newCommand) Run(ctx context.Context, cd *simplecobra.Commandeer, args [
 	return nil
 }
 
-func (c *newCommand) WithCobraCommand(cmd *cobra.Command) error {
+func (c *newCommand) Init(cd *simplecobra.Commandeer) error {
+	cmd := cd.CobraCommand
 	cmd.Short = "Create new content for your site"
 	cmd.Long = `Create a new content file and automatically set the date and title.
 It will guess which kind of file to create based on the path provided.
@@ -284,7 +285,7 @@ Ensure you run this within the root directory of your site.`
 	return nil
 }
 
-func (c *newCommand) Init(cd, runner *simplecobra.Commandeer) error {
+func (c *newCommand) PreRun(cd, runner *simplecobra.Commandeer) error {
 	c.rootCmd = cd.Root.Command.(*rootCommand)
 	return nil
 }
diff --git a/commands/server.go b/commands/server.go
index 5c2fd7704..8cd7a961f 100644
--- a/commands/server.go
+++ b/commands/server.go
@@ -54,7 +54,6 @@ import (
 	"github.com/gohugoio/hugo/transform"
 	"github.com/gohugoio/hugo/transform/livereloadinject"
 	"github.com/spf13/afero"
-	"github.com/spf13/cobra"
 	"github.com/spf13/fsync"
 	"golang.org/x/sync/errgroup"
 	"golang.org/x/sync/semaphore"
@@ -99,8 +98,7 @@ func newHugoBuilder(r *rootCommand, s *serverCommand, onConfigLoaded ...func(rel
 func newServerCommand() *serverCommand {
 	var c *serverCommand
 	c = &serverCommand{
-		buildFlags: &buildFlags{},
-		quit:       make(chan bool),
+		quit: make(chan bool),
 	}
 	return c
 }
@@ -408,10 +406,6 @@ type serverCommand struct {
 	doLiveReload bool
 
 	// Flags.
-
-	// Common build flags.
-	*buildFlags
-
 	renderToDisk        bool
 	renderStaticToDisk  bool
 	navigateToChanged   bool
@@ -472,7 +466,8 @@ func (c *serverCommand) Run(ctx context.Context, cd *simplecobra.Commandeer, arg
 	return c.serve()
 }
 
-func (c *serverCommand) WithCobraCommand(cmd *cobra.Command) error {
+func (c *serverCommand) Init(cd *simplecobra.Commandeer) error {
+	cmd := cd.CobraCommand
 	cmd.Short = "A high performance webserver"
 	cmd.Long = `Hugo provides its own webserver which builds and serves the site.
 While hugo server is high performance, it is a webserver with limited options.
@@ -504,12 +499,13 @@ of a second, you will be able to save and see your changes nearly instantly.`
 	cmd.Flags().String("memstats", "", "log memory usage to this file")
 	cmd.Flags().String("meminterval", "100ms", "interval to poll memory usage (requires --memstats), valid time units are \"ns\", \"us\" (or \"µs\"), \"ms\", \"s\", \"m\", \"h\".")
 
-	applyLocalBuildFlags(cmd, c.buildFlags)
+	r := cd.Root.Command.(*rootCommand)
+	applyLocalBuildFlags(cmd, r)
 
 	return nil
 }
 
-func (c *serverCommand) Init(cd, runner *simplecobra.Commandeer) error {
+func (c *serverCommand) PreRun(cd, runner *simplecobra.Commandeer) error {
 	c.r = cd.Root.Command.(*rootCommand)
 
 	c.hugoBuilder = newHugoBuilder(
diff --git a/commands/xcommand_template.go b/commands/xcommand_template.go
index 6bb507a5e..7ceeffb19 100644
--- a/commands/xcommand_template.go
+++ b/commands/xcommand_template.go
@@ -66,13 +66,14 @@ func (c *templateCommand) Run(ctx context.Context, cd *simplecobra.Commandeer, a
 	return nil
 }
 
-func (c *templateCommand) WithCobraCommand(cmd *cobra.Command) error {
+func (c *templateCommand) Init(cd *simplecobra.Commandeer) error {
+	cmd := cd.CobraCommand
 	cmd.Short = "Print the site configuration"
 	cmd.Long = `Print the site configuration, both default and custom settings.`
 	return nil
 }
 
-func (c *templateCommand) Init(cd, runner *simplecobra.Commandeer) error {
+func (c *templateCommand) PreRun(cd, runner *simplecobra.Commandeer) error {
 	c.r = cd.Root.Command.(*rootCommand)
 	return nil
 }
diff --git a/config/allconfig/allconfig.go b/config/allconfig/allconfig.go
index a51914772..c09962f63 100644
--- a/config/allconfig/allconfig.go
+++ b/config/allconfig/allconfig.go
@@ -23,6 +23,7 @@ import (
 	"sort"
 	"strconv"
 	"strings"
+	"sync"
 	"time"
 
 	"github.com/gohugoio/hugo/cache/filecache"
@@ -92,7 +93,7 @@ type Config struct {
 	// For internal use only.
 	Internal InternalConfig `mapstructure:"-" json:"-"`
 	// For internal use only.
-	C ConfigCompiled `mapstructure:"-" json:"-"`
+	C *ConfigCompiled `mapstructure:"-" json:"-"`
 
 	RootConfig
 
@@ -188,6 +189,8 @@ type configCompiler interface {
 
 func (c Config) cloneForLang() *Config {
 	x := c
+	x.C = nil
+
 	// Collapse all static dirs to one.
 	x.StaticDir = x.staticDirs()
 	// These will go away soon ...
@@ -302,7 +305,7 @@ func (c *Config) CompileConfig() error {
 		}
 	}
 
-	c.C = ConfigCompiled{
+	c.C = &ConfigCompiled{
 		Timeout:           timeout,
 		BaseURL:           baseURL,
 		BaseURLLiveReload: baseURL,
@@ -329,11 +332,11 @@ func (c *Config) CompileConfig() error {
 	return nil
 }
 
-func (c Config) IsKindEnabled(kind string) bool {
+func (c *Config) IsKindEnabled(kind string) bool {
 	return !c.C.DisabledKinds[kind]
 }
 
-func (c Config) IsLangDisabled(lang string) bool {
+func (c *Config) IsLangDisabled(lang string) bool {
 	return c.C.DisabledLanguages[lang]
 }
 
@@ -356,10 +359,17 @@ type ConfigCompiled struct {
 	// With themes/modules we compute the configuration in multiple passes, and
 	// errors with missing output format definitions may resolve itself.
 	transientErr error
+
+	mu sync.Mutex
 }
 
 // This may be set after the config is compiled.
-func (c *ConfigCompiled) SetMainSections(sections []string) {
+func (c *ConfigCompiled) SetMainSectionsIfNotSet(sections []string) {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	if len(c.MainSections) > 0 {
+		return
+	}
 	c.MainSections = sections
 }
 
diff --git a/go.mod b/go.mod
index 171d3921f..d494ee7eb 100644
--- a/go.mod
+++ b/go.mod
@@ -95,7 +95,7 @@ require (
 	github.com/aws/aws-sdk-go-v2/service/sts v1.7.0 // indirect
 	github.com/aws/smithy-go v1.8.0 // indirect
 	github.com/bep/helpers v0.4.0 // indirect
-	github.com/bep/simplecobra v0.2.0 // indirect
+	github.com/bep/simplecobra v0.3.0 // indirect
 	github.com/cpuguy83/go-md2man/v2 v2.0.2 // indirect
 	github.com/dlclark/regexp2 v1.7.0 // indirect
 	github.com/go-openapi/jsonpointer v0.19.5 // indirect
diff --git a/go.sum b/go.sum
index 30af63f39..50f1ea6a7 100644
--- a/go.sum
+++ b/go.sum
@@ -187,6 +187,8 @@ github.com/bep/overlayfs v0.6.0 h1:sgLcq/qtIzbaQNl2TldGXOkHvqeZB025sPvHOQL+DYo=
 github.com/bep/overlayfs v0.6.0/go.mod h1:NFjSmn3kCqG7KX2Lmz8qT8VhPPCwZap3UNogXawoQHM=
 github.com/bep/simplecobra v0.2.0 h1:gfdZZ8QlPBMC9R9DRzUsxExR3FyuNtRkqMJqK98SBno=
 github.com/bep/simplecobra v0.2.0/go.mod h1:EOp6bCKuuHmwA9bQcRC8LcDB60co2Cmht5X4xMIOwf0=
+github.com/bep/simplecobra v0.3.0 h1:BEeb/Q5qdsv5Yy9Go30ynZtAbI+jHV4f5VtNSXvp91E=
+github.com/bep/simplecobra v0.3.0/go.mod h1:EOp6bCKuuHmwA9bQcRC8LcDB60co2Cmht5X4xMIOwf0=
 github.com/bep/tmc v0.5.1 h1:CsQnSC6MsomH64gw0cT5f+EwQDcvZz4AazKunFwTpuI=
 github.com/bep/tmc v0.5.1/go.mod h1:tGYHN8fS85aJPhDLgXETVKp+PR382OvFi2+q2GkGsq0=
 github.com/bep/workers v1.0.0 h1:U+H8YmEaBCEaFZBst7GcRVEoqeRC9dzH2dWOwGmOchg=
diff --git a/hugolib/content_map_page.go b/hugolib/content_map_page.go
index 1b6fd40e9..6f02e2e29 100644
--- a/hugolib/content_map_page.go
+++ b/hugolib/content_map_page.go
@@ -743,9 +743,12 @@ func (m *pageMaps) AssemblePages() error {
 		sw := &sectionWalker{m: pm.contentMap}
 		a := sw.applyAggregates()
 
-		if a.mainSection != "" && len(pm.s.s.conf.C.MainSections) == 0 {
+		if a.mainSection != "" {
+			// Note, sites that have no custom config share a common config struct pointer.
+			// This means that we currently do not support setting different values per language.
+			// The end user can, however, configure this per language if needed.
 			mainSections := []string{strings.TrimRight(a.mainSection, "/")}
-			pm.s.s.conf.C.SetMainSections(mainSections)
+			pm.s.s.conf.C.SetMainSectionsIfNotSet(mainSections)
 		}
 		pm.s.lastmod = a.datesAll.Lastmod()
 		if resource.IsZeroDates(pm.s.home) {
diff --git a/testscripts/unfinished/server.txt b/testscripts/commands/server.txt
index fd6b200bc..fd6b200bc 100644
--- a/testscripts/unfinished/server.txt
+++ b/testscripts/commands/server.txt