Change compiler version lookup approach to prevent duplicating flags

cmd/fyne/internal/commands/build.go

@@ -362,7 +362,12 @@ func (b *Builder) applyCAndLDFlags(env *[]string, os string) {
 	}
 
 	arch := targetArch()
-	cflagsHardening := hardeningCFlagsLookup(ccVersion(), os, arch)
+	ccVer, err := ccVersionAndDefaultFlags()
+	if err != nil {
+		fyne.LogError("failed to get compiler version and default flags", err)
+		ccVer = ccVersion()
+	}
+	cflagsHardening := hardeningCFlagsLookup(ccVer, os, arch)
 	if cflagsHardening != "" {
 		cflags = append(cflags, cflagsHardening)
 	}

cmd/fyne/internal/commands/hardening_flags.go

@@ -3,6 +3,8 @@ package commands
 import (
 	"os"
 	"os/exec"
+	"regexp"
+	"strings"
 
 	"golang.org/x/mod/semver"
 
@@ -28,12 +30,16 @@ var hardeningFlagsTable = []hardeningFlags{
 	//revive:enable:add-constant
 }
 
-func ccVersion() string {
+func ccProg() string {
 	cc, ok := os.LookupEnv("CC")
 	if !ok {
-		cc = "cc"
+		return "cc"
 	}
+	return cc
+}
 
+func ccVersion() string {
+	cc := ccProg()
 	cmd := exec.Command(cc, "--version")
 	out, err := cmd.CombinedOutput()
 	if err != nil {
@@ -43,11 +49,60 @@ func ccVersion() string {
 	return string(out)
 }
 
+const ccTestFlagsCode = `
+int main(int argc, char **argv) {
+	return 0;
+}
+`
+
+func ccVersionAndDefaultFlags() (string, error) {
+	f, err := os.CreateTemp("", "fyne-check-cc-*.c")
+	if err != nil {
+		return "", err
+	}
+	inFile := f.Name()
+	outFile := strings.TrimSuffix(inFile, ".c")
+	defer func() {
+		_ = os.Remove(inFile)
+		_ = os.Remove(outFile)
+	}()
+
+	if _, err := f.WriteString(ccTestFlagsCode); err != nil {
+		return "", err
+	}
+	if err := f.Close(); err != nil {
+		return "", err
+	}
+
+	cmd := exec.Command(ccProg(), "-Q", "-v", "-o", outFile, inFile)
+	out, err := cmd.CombinedOutput()
+	if err != nil {
+		return "", err
+	}
+
+	return string(out), nil
+}
+
+func gccDefaultFlags(s string) []string {
+	re := regexp.MustCompile(`(?ms)^options enabled:((?:\s+\S+\n?)*)`)
+	m := re.FindStringSubmatch(s)
+	if len(m) < 2 {
+		return nil
+	}
+	return strings.Fields(m[1])
+}
+
 func hardeningCFlagsLookup(out, goos, arch string) string {
 	info, err := util.DetectCompiler(out, goos)
 	if err != nil {
 		return ""
 	}
+
+	var defs []string
+	if info.Name == "gcc" {
+		defs = gccDefaultFlags(out)
+	}
+
 	for _, e := range hardeningFlagsTable {
 		//revive:disable:add-constant
 		if e.cc != "*" && e.cc != info.Name {
@@ -65,8 +120,29 @@ func hardeningCFlagsLookup(out, goos, arch string) string {
 		if e.maxVer != "*" && semver.Compare("v"+info.Version, "v"+e.maxVer) > 0 {
 			continue
 		}
-		return e.cflags
+		return dedupeFlags(e.cflags, defs)
 		//revive:enable:add-constant
 	}
-	return hardeningCFLAGS
+	return dedupeFlags(hardeningCFLAGS, defs)
+}
+
+func dedupeFlags(s string, defs []string) string {
+	if len(defs) == 0 {
+		return s
+	}
+
+	seen := make(map[string]struct{})
+	for _, flag := range defs {
+		seen[flag] = struct{}{}
+	}
+
+	r := []string{}
+	for _, flag := range strings.Fields(s) {
+		if _, found := seen[flag]; found {
+			continue
+		}
+		seen[flag] = struct{}{}
+		r = append(r, flag)
+	}
+	return util.JoinSpace(r)
 }

cmd/fyne/internal/commands/hardening_flags_test.go

@@ -34,3 +34,31 @@ func Test_hardeningCFlagsLookup(t *testing.T) {
 	// darwin/arm64 doesn't do -fcf-protection
 	assert.Equal(t, "-D_FORTIFY_SOURCE=3 -fstack-protector-strong", hardeningCFlagsLookup("Apple clang version 17.0.0 (clang-1700.0.13.5)", "darwin", "arm64"))
 }
+
+func Test_gccDefaultFlags(t *testing.T) {
+	in := `
+GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
+options passed:  -v -auxbase
+options enabled:  -falign-loops -fargument-alias
+ -fasynchronous-unwind-tables -fbranch-count-reg -fcommon -fearly-inlining
+ -feliminate-unused-debug-types -femit-class-debug-always -ffunction-cse
+ -fgcse-lm -finline-functions-called-once -fivopts -fkeep-static-consts
+ -fleading-underscore -fmath-errno -fmove-loop-invariants -fpeephole -fpic
+ -fpie -freg-struct-return -fsched-interblock -fsched-spec
+ -fsched-stalled-insns-dep -fshow-column -fsplit-ivs-in-unroller
+ -ftoplevel-reorder -ftrapping-math -ftree-loop-im -ftree-loop-ivcanon
+ -ftree-loop-optimize -ftree-vect-loop-version -funwind-tables
+ -fvar-tracking -m128bit-long-double -m64 -m80387
+ -maccumulate-outgoing-args -malign-stringops -mfancy-math-387
+ -mfp-ret-in-387 -mieee-fp -mmmx -mpush-args -mred-zone -msse -msse2
+Compiler executable checksum: 1e242b9c9b970b8bb2f3765bba204637
+`
+	x := gccDefaultFlags(in)
+	assert.NotNil(t, x)
+}
+
+func Test_ccVersionAndDefaultFlags(t *testing.T) {
+	s, err := ccVersionAndDefaultFlags()
+	assert.NoError(t, err)
+	assert.NotEmpty(t, s)
+}