From f4df0bfcbf748a3954d2b8b7865bf27db8f8ee79 Mon Sep 17 00:00:00 2001
From: BEN GHORBEL Oussama <d.oussamabenghorbel@gmail.com>
Date: Mon, 30 Dec 2024 18:13:38 +0100
Subject: [PATCH] [#58] Ability to provide custom ld and gc flags

---
 cmd/builder/internal/builder/config.go      |  3 ++-
 cmd/builder/internal/builder/config_test.go |  2 ++
 cmd/builder/internal/builder/main.go        | 19 +++++++++++++++----
 cmd/builder/internal/builder/main_test.go   | 10 ++++++++++
 cmd/builder/internal/command.go             |  4 ++++
 5 files changed, 33 insertions(+), 5 deletions(-)

diff --git a/cmd/builder/internal/builder/config.go b/cmd/builder/internal/builder/config.go
index cb83375316b..65317d42033 100644
--- a/cmd/builder/internal/builder/config.go
+++ b/cmd/builder/internal/builder/config.go
@@ -35,6 +35,7 @@ type Config struct {
 	SkipGetModules       bool   `mapstructure:"-"`
 	SkipStrictVersioning bool   `mapstructure:"-"`
 	LDFlags              string `mapstructure:"-"`
+	GCFlags              string `mapstructure:"-"`
 	Verbose              bool   `mapstructure:"-"`
 
 	Distribution      Distribution `mapstructure:"dist"`
@@ -71,7 +72,7 @@ type Distribution struct {
 	OutputPath       string `mapstructure:"output_path"`
 	Version          string `mapstructure:"version"`
 	BuildTags        string `mapstructure:"build_tags"`
-	DebugCompilation bool   `mapstructure:"debug_compilation"`
+	DebugCompilation bool   `mapstructure:"debug_compilation"` // TODO depercate?
 }
 
 // Module represents a receiver, exporter, processor or extension for the distribution
diff --git a/cmd/builder/internal/builder/config_test.go b/cmd/builder/internal/builder/config_test.go
index 14040dd50aa..014569ac659 100644
--- a/cmd/builder/internal/builder/config_test.go
+++ b/cmd/builder/internal/builder/config_test.go
@@ -179,6 +179,8 @@ func TestNewDefaultConfig(t *testing.T) {
 	require.NoError(t, cfg.Validate())
 	assert.False(t, cfg.Distribution.DebugCompilation)
 	assert.Empty(t, cfg.Distribution.BuildTags)
+	assert.Empty(t, cfg.LDFlags)
+	assert.Empty(t, cfg.GCFlags)
 }
 
 func TestNewBuiltinConfig(t *testing.T) {
diff --git a/cmd/builder/internal/builder/main.go b/cmd/builder/internal/builder/main.go
index 197d1038613..2f570fc7fc7 100644
--- a/cmd/builder/internal/builder/main.go
+++ b/cmd/builder/internal/builder/main.go
@@ -109,17 +109,28 @@ func Compile(cfg *Config) error {
 
 	cfg.Logger.Info("Compiling")
 
-	ldflags := "-s -w"
+	var ldflags = "-s -w" // we strip the symbols by default for smaller binaries
+	var gcflags = ""
 
 	args := []string{"build", "-trimpath", "-o", cfg.Distribution.Name}
 	if cfg.Distribution.DebugCompilation {
 		cfg.Logger.Info("Debug compilation is enabled, the debug symbols will be left on the resulting binary")
 		ldflags = cfg.LDFlags
-		args = append(args, "-gcflags=all=-N -l")
-	} else if len(cfg.LDFlags) > 0 {
-		ldflags += " " + cfg.LDFlags
+		gcflags = "all=-N -l"
+	} else {
+		if len(cfg.LDFlags) > 0 {
+			cfg.Logger.Info("Using custom ldflags", zap.String("ldflags", cfg.LDFlags))
+			ldflags = cfg.LDFlags
+		}
+		if len(cfg.GCFlags) > 0 {
+			cfg.Logger.Info("Using custom gcflags", zap.String("gcflags", cfg.GCFlags))
+			gcflags = cfg.GCFlags
+		}
 	}
+	
 	args = append(args, "-ldflags="+ldflags)
+	args = append(args, "-gcflags="+gcflags)
+
 	if cfg.Distribution.BuildTags != "" {
 		args = append(args, "-tags", cfg.Distribution.BuildTags)
 	}
diff --git a/cmd/builder/internal/builder/main_test.go b/cmd/builder/internal/builder/main_test.go
index 8220e48df85..4b02a02b416 100644
--- a/cmd/builder/internal/builder/main_test.go
+++ b/cmd/builder/internal/builder/main_test.go
@@ -251,6 +251,16 @@ func TestGenerateAndCompile(t *testing.T) {
 				return cfg
 			},
 		},
+		{
+			name: "GCFlags Compilation",
+			cfgBuilder: func(t *testing.T) *Config {
+				cfg := newTestConfig(t)
+				cfg.Distribution.OutputPath = t.TempDir()
+				cfg.Replaces = append(cfg.Replaces, replaces...)
+				cfg.GCFlags = `all=-N -l`
+				return cfg
+			},
+		},
 		{
 			name: "Build Tags Compilation",
 			cfgBuilder: func(t *testing.T) *Config {
diff --git a/cmd/builder/internal/command.go b/cmd/builder/internal/command.go
index fa1fd235233..c64316fbd2f 100644
--- a/cmd/builder/internal/command.go
+++ b/cmd/builder/internal/command.go
@@ -27,6 +27,7 @@ const (
 	skipGetModulesFlag         = "skip-get-modules"
 	skipStrictVersioningFlag   = "skip-strict-versioning"
 	ldflagsFlag                = "ldflags"
+	gcflagsFlag 			   = "gcflags"
 	distributionOutputPathFlag = "output-path"
 	verboseFlag                = "verbose"
 )
@@ -84,6 +85,7 @@ func initFlags(flags *flag.FlagSet) error {
 	flags.Bool(skipStrictVersioningFlag, true, "Whether builder should skip strictly checking the calculated versions following dependency resolution")
 	flags.Bool(verboseFlag, false, "Whether builder should print verbose output (default false)")
 	flags.String(ldflagsFlag, "", `ldflags to include in the "go build" command`)
+	flags.String(gcflagsFlag, "", `gcflags to include in the "go build" command`)
 	flags.String(distributionOutputPathFlag, "", "Where to write the resulting files")
 	return flags.MarkDeprecated(distributionOutputPathFlag, "use config distribution::output_path")
 }
@@ -147,6 +149,8 @@ func applyFlags(flags *flag.FlagSet, cfg *builder.Config) error {
 
 	cfg.LDFlags, err = flags.GetString(ldflagsFlag)
 	errs = multierr.Append(errs, err)
+	cfg.GCFlags, err = flags.GetString(gcflagsFlag)
+	errs = multierr.Append(errs, err)
 	cfg.Verbose, err = flags.GetBool(verboseFlag)
 	errs = multierr.Append(errs, err)