[chore] detect the presence of ld/gc flags.

cmd/builder/README.md

@@ -115,15 +115,15 @@ Use `ocb --help` to learn about which flags are available.
 By default, the LDflags are set to -s -w, which strips debugging symbols to produce a smaller OpenTelemetry Collector binary. To retain debugging symbols and DWARF debugging data in the binary, override the LDflags as shown:
 
 ```console 
-ocb --ldflags=" " --config=builder-config.yaml.
+ocb --ldflags="" --config=builder-config.yaml.
 ```
 
 ### Debugging with Delve
 
 To ensure the code being executed matches the written code exactly, debugging symbols must be preserved, and compiler inlining and optimizations disabled. You can achieve this in two ways:
 
 1. Set the configuration property `debug_compilation` to true.
-2. Manually override the ldflags and gcflags `ocb --ldflags=" " --gcflags="all=-N -l" --config=builder-config.yaml.`
+2. Manually override the ldflags and gcflags `ocb --ldflags="" --gcflags="all=-N -l" --config=builder-config.yaml.`
 
 Then install `go-delve` and run OpenTelemetry Collector with `dlv` command as the following example:
 

cmd/builder/internal/builder/config.go

@@ -35,7 +35,9 @@ type Config struct {
 	SkipGetModules       bool   `mapstructure:"-"`
 	SkipStrictVersioning bool   `mapstructure:"-"`
 	LDFlags              string `mapstructure:"-"`
+	LDSet 				 bool   `mapstructure:"-"` // only used to override LDFlags
 	GCFlags              string `mapstructure:"-"`
+	GCSet				 bool   `mapstructure:"-"` // only used to override GCFlags
 	Verbose              bool   `mapstructure:"-"`
 
 	Distribution      Distribution `mapstructure:"dist"`

cmd/builder/internal/builder/config_test.go

@@ -179,7 +179,9 @@ func TestNewDefaultConfig(t *testing.T) {
 	require.NoError(t, cfg.Validate())
 	assert.False(t, cfg.Distribution.DebugCompilation)
 	assert.Empty(t, cfg.Distribution.BuildTags)
+	assert.False(t, cfg.LDSet)
 	assert.Empty(t, cfg.LDFlags)
+	assert.False(t, cfg.GCSet)
 	assert.Empty(t, cfg.GCFlags)
 }
 

cmd/builder/internal/builder/main.go

@@ -118,11 +118,11 @@ func Compile(cfg *Config) error {
 		ldflags = cfg.LDFlags
 		gcflags = "all=-N -l"
 	} else {
-		if len(cfg.LDFlags) > 0 {
+		if cfg.LDSet {
 			cfg.Logger.Info("Using custom ldflags", zap.String("ldflags", cfg.LDFlags))
 			ldflags = cfg.LDFlags
 		}
-		if len(cfg.GCFlags) > 0 {
+		if cfg.GCSet {
 			cfg.Logger.Info("Using custom gcflags", zap.String("gcflags", cfg.GCFlags))
 			gcflags = cfg.GCFlags
 		}

cmd/builder/internal/command.go

@@ -27,7 +27,7 @@ const (
 	skipGetModulesFlag         = "skip-get-modules"
 	skipStrictVersioningFlag   = "skip-strict-versioning"
 	ldflagsFlag                = "ldflags"
-	gcflagsFlag 			   = "gcflags"
+	gcflagsFlag                = "gcflags"
 	distributionOutputPathFlag = "output-path"
 	verboseFlag                = "verbose"
 )
@@ -147,10 +147,17 @@ func applyFlags(flags *flag.FlagSet, cfg *builder.Config) error {
 	cfg.SkipStrictVersioning, err = flags.GetBool(skipStrictVersioningFlag)
 	errs = multierr.Append(errs, err)
 
-	cfg.LDFlags, err = flags.GetString(ldflagsFlag)
-	errs = multierr.Append(errs, err)
-	cfg.GCFlags, err = flags.GetString(gcflagsFlag)
-	errs = multierr.Append(errs, err)
+	if flags.Changed(ldflagsFlag) {
+		cfg.LDSet = true
+		cfg.LDFlags, err = flags.GetString(ldflagsFlag)
+		errs = multierr.Append(errs, err)
+	}
+	if flags.Changed(gcflagsFlag) {
+		cfg.GCSet = true
+		cfg.GCFlags, err = flags.GetString(gcflagsFlag)
+		errs = multierr.Append(errs, err)
+	}
+
 	cfg.Verbose, err = flags.GetBool(verboseFlag)
 	errs = multierr.Append(errs, err)