build: pass CFLAGS and LDFLAGS to clang

compiler/internal/build/build.go

@@ -488,7 +488,7 @@ func linkMainPkg(ctx *context, pkg *packages.Package, pkgs []*aPackage, linkArgs
 	if verbose {
 		fmt.Fprintln(os.Stderr, "clang", args)
 	}
-	err = ctx.env.Clang().Exec(args...)
+	err = ctx.env.Clang().Link(args...)
 	check(err)
 
 	if IsRpathChangeEnabled() && runtime.GOOS == "darwin" {
@@ -870,7 +870,7 @@ func clFile(ctx *context, args []string, cFile, expFile string, procFile func(li
 	if verbose {
 		fmt.Fprintln(os.Stderr, "clang", args)
 	}
-	err := ctx.env.Clang().Exec(args...)
+	err := ctx.env.Clang().Compile(args...)
 	check(err)
 	procFile(llFile)
 }

xtool/clang/clang.go

@@ -20,6 +20,7 @@ import (
 	"io"
 	"os"
 	"os/exec"
+	"strings"
 )
 
 // -----------------------------------------------------------------------------
@@ -40,6 +41,32 @@ func New(app string) *Cmd {
 	return &Cmd{app, os.Stdout, os.Stderr}
 }
 
+func (p *Cmd) Compile(args ...string) error {
+	// Parse CFLAGS environment variable into separate arguments
+	cflags := strings.Fields(os.Getenv("CFLAGS"))
+	if len(cflags) > 0 {
+		// Create a new slice with capacity for all arguments
+		newArgs := make([]string, 0, len(cflags)+len(args))
+		newArgs = append(newArgs, cflags...)
+		newArgs = append(newArgs, args...)
+		args = newArgs
+	}
+	return p.Exec(args...)
+}
+
+func (p *Cmd) Link(args ...string) error {
+	// Parse LDFLAGS environment variable into separate arguments
+	ldflags := strings.Fields(os.Getenv("LDFLAGS"))
+	if len(ldflags) > 0 {
+		// Create a new slice with capacity for all arguments
+		newArgs := make([]string, 0, len(ldflags)+len(args))
+		newArgs = append(newArgs, ldflags...)
+		newArgs = append(newArgs, args...)
+		args = newArgs
+	}
+	return p.Exec(args...)
+}
+
 // Exec executes a clang command.
 func (p *Cmd) Exec(args ...string) error {
 	cmd := exec.Command(p.app, args...)