gdb: enable to specify multiple candidates for gdb

compileopts/target.go

@@ -7,6 +7,7 @@ import (
 	"errors"
 	"io"
 	"os"
+	"os/exec"
 	"path/filepath"
 	"reflect"
 	"runtime"
@@ -42,7 +43,7 @@ type TargetSpec struct {
 	ExtraFiles       []string `json:"extra-files"`
 	Emulator         []string `json:"emulator" override:"copy"` // inherited Emulator must not be append
 	FlashCommand     string   `json:"flash-command"`
-	GDB              string   `json:"gdb"`
+	GDB              []string `json:"gdb"`
 	PortReset        string   `json:"flash-1200-bps-reset"`
 	FlashMethod      string   `json:"flash-method"`
 	FlashVolume      string   `json:"msd-volume-name"`
@@ -240,7 +241,7 @@ func defaultTarget(goos, goarch, triple string) (*TargetSpec, error) {
 		Compiler:  "clang",
 		Linker:    "cc",
 		CFlags:    []string{"--target=" + triple},
-		GDB:       "gdb",
+		GDB:       []string{"gdb"},
 		PortReset: "false",
 	}
 	if goos == "darwin" {
@@ -253,7 +254,7 @@ func defaultTarget(goos, goarch, triple string) (*TargetSpec, error) {
 	}
 	if goarch != runtime.GOARCH {
 		// Some educated guesses as to how to invoke helper programs.
-		spec.GDB = "gdb-multiarch"
+		spec.GDB = []string{"gdb-multiarch"}
 		if goarch == "arm" && goos == "linux" {
 			spec.CFlags = append(spec.CFlags, "--sysroot=/usr/arm-linux-gnueabihf")
 			spec.Linker = "arm-linux-gnueabihf-gcc"
@@ -271,3 +272,17 @@ func defaultTarget(goos, goarch, triple string) (*TargetSpec, error) {
 	}
 	return &spec, nil
 }
+
+// LookupGDB looks up a gdb executable.
+func (spec *TargetSpec) LookupGDB() (string, error) {
+	if len(spec.GDB) == 0 {
+		return "", errors.New("gdb not configured in the target specification")
+	}
+	for _, d := range spec.GDB {
+		_, err := exec.LookPath(d)
+		if err == nil {
+			return d, nil
+		}
+	}
+	return "", errors.New("no gdb found configured in the target specification (" + strings.Join(spec.GDB, ", ") + ")")
+}

main.go

@@ -344,8 +344,9 @@ func FlashGDB(pkgName string, ocdOutput bool, options *compileopts.Options) erro
 	if err != nil {
 		return err
 	}
-	if config.Target.GDB == "" {
-		return errors.New("gdb not configured in the target specification")
+	gdb, err := config.Target.LookupGDB()
+	if err != nil {
+		return err
 	}
 
 	return builder.Build(pkgName, "", config, func(result builder.BuildResult) error {
@@ -490,7 +491,7 @@ func FlashGDB(pkgName string, ocdOutput bool, options *compileopts.Options) erro
 		for _, cmd := range gdbCommands {
 			params = append(params, "-ex", cmd)
 		}
-		cmd := executeCommand(config.Options, config.Target.GDB, params...)
+		cmd := executeCommand(config.Options, gdb, params...)
 		cmd.Stdin = os.Stdin
 		cmd.Stdout = os.Stdout
 		cmd.Stderr = os.Stderr

targets/avr.json

@@ -19,5 +19,5 @@
 		"src/internal/task/task_stack_avr.S",
 		"src/runtime/gc_avr.S"
 	],
-	"gdb": "avr-gdb"
+	"gdb": ["avr-gdb"]
 }

targets/cortex-m.json

@@ -28,5 +28,5 @@
 		"src/internal/task/task_stack_cortexm.S",
 		"src/runtime/gc_arm.S"
 	],
-	"gdb": "gdb-multiarch"
+	"gdb": ["gdb-multiarch", "arm-none-eabi-gdb"]
 }

targets/cortex-m7.json

@@ -4,6 +4,5 @@
 	"cflags": [
 		"--target=armv7em-none-eabi",
 		"-Qunused-arguments"
-	],
-	"gdb": "arm-none-eabi-gdb"
+	]
 }

targets/gameboy-advance.json

@@ -27,6 +27,6 @@
 		"targets/gameboy-advance.s",
 		"src/runtime/gc_arm.S"
 	],
-	"gdb": "gdb-multiarch",
+	"gdb": ["gdb-multiarch"],
 	"emulator": ["mgba", "-3"]
 }

targets/riscv.json

@@ -21,5 +21,5 @@
 		"src/runtime/gc_riscv.S",
 		"src/device/riscv/handleinterrupt.S"
 	],
-	"gdb": "riscv64-unknown-elf-gdb"
+	"gdb": ["riscv64-unknown-elf-gdb"]
 }