all: make emulator command a string instead of a []string

This matches the flash-command and is generally a bit easier to work
with.
This commit also prepares for allowing multiple formats to be used in
the emulator command, which is necessary for the esp32.

compileopts/config.go

@@ -10,6 +10,7 @@ import (
 	"regexp"
 	"strings"
 
+	"github.com/google/shlex"
 	"github.com/tinygo-org/tinygo/goenv"
 )
 
@@ -494,13 +495,38 @@ func (c *Config) WasmAbi() string {
 	return c.Target.WasmAbi
 }
 
-// Emulator returns the emulator target config
-func (c *Config) Emulator() []string {
-	var emulator []string
-	for _, s := range c.Target.Emulator {
-		emulator = append(emulator, strings.ReplaceAll(s, "{root}", goenv.Get("TINYGOROOT")))
+// EmulatorName is a shorthand to get the command for this emulator, something
+// like qemu-system-arm or simavr.
+func (c *Config) EmulatorName() string {
+	parts := strings.SplitN(c.Target.Emulator, " ", 2)
+	if len(parts) > 1 {
+		return parts[0]
 	}
-	return emulator
+	return ""
+}
+
+// EmulatorFormat returns the binary format for the emulator and the associated
+// file extension. An empty string means to pass directly whatever the linker
+// produces directly without conversion.
+func (c *Config) EmulatorFormat() (format, fileExt string) {
+	return "", ""
+}
+
+// Emulator returns a ready-to-run command to run the given binary in an
+// emulator. Give it the format (returned by EmulatorFormat()) and the path to
+// the compiled binary.
+func (c *Config) Emulator(format, binary string) ([]string, error) {
+	parts, err := shlex.Split(c.Target.Emulator)
+	if err != nil {
+		return nil, fmt.Errorf("could not parse emulator command: %w", err)
+	}
+	var emulator []string
+	for _, s := range parts {
+		s = strings.ReplaceAll(s, "{root}", goenv.Get("TINYGOROOT"))
+		s = strings.ReplaceAll(s, "{"+format+"}", binary)
+		emulator = append(emulator, s)
+	}
+	return emulator, nil
 }
 
 type TestConfig struct {

compileopts/target.go

@@ -44,8 +44,8 @@ type TargetSpec struct {
 	LDFlags          []string `json:"ldflags"`
 	LinkerScript     string   `json:"linkerscript"`
 	ExtraFiles       []string `json:"extra-files"`
-	RP2040BootPatch  *bool    `json:"rp2040-boot-patch"`        // Patch RP2040 2nd stage bootloader checksum
-	Emulator         []string `json:"emulator" override:"copy"` // inherited Emulator must not be append
+	RP2040BootPatch  *bool    `json:"rp2040-boot-patch"` // Patch RP2040 2nd stage bootloader checksum
+	Emulator         string   `json:"emulator"`
 	FlashCommand     string   `json:"flash-command"`
 	GDB              []string `json:"gdb"`
 	PortReset        string   `json:"flash-1200-bps-reset"`
@@ -90,19 +90,8 @@ func (spec *TargetSpec) overrideProperties(child *TargetSpec) {
 			if !src.IsNil() {
 				dst.Set(src)
 			}
-		case reflect.Slice: // for slices...
-			if src.Len() > 0 { // ... if not empty ...
-				switch tag := field.Tag.Get("override"); tag {
-				case "copy":
-					// copy the field of child to spec
-					dst.Set(src)
-				case "append", "":
-					// or append the field of child to spec
-					dst.Set(reflect.AppendSlice(dst, src))
-				default:
-					panic("override mode must be 'copy' or 'append' (default). I don't know how to '" + tag + "'.")
-				}
-			}
+		case reflect.Slice: // for slices, append the field
+			dst.Set(reflect.AppendSlice(dst, src))
 		default:
 			panic("unknown field type : " + kind.String())
 		}
@@ -335,20 +324,20 @@ func defaultTarget(goos, goarch, triple string) (*TargetSpec, error) {
 			case "386":
 				// amd64 can _usually_ run 32-bit programs, so skip the emulator in that case.
 				if runtime.GOARCH != "amd64" {
-					spec.Emulator = []string{"qemu-i386"}
+					spec.Emulator = "qemu-i386 {}"
 				}
 			case "amd64":
-				spec.Emulator = []string{"qemu-x86_64"}
+				spec.Emulator = "qemu-x86_64 {}"
 			case "arm":
-				spec.Emulator = []string{"qemu-arm"}
+				spec.Emulator = "qemu-arm {}"
 			case "arm64":
-				spec.Emulator = []string{"qemu-aarch64"}
+				spec.Emulator = "qemu-aarch64 {}"
 			}
 		}
 	}
 	if goos != runtime.GOOS {
 		if goos == "windows" {
-			spec.Emulator = []string{"wine"}
+			spec.Emulator = "wine {}"
 		}
 	}
 	return &spec, nil

compileopts/target_test.go

@@ -29,7 +29,6 @@ func TestOverrideProperties(t *testing.T) {
 		CPU:              "baseCpu",
 		CFlags:           []string{"-base-foo", "-base-bar"},
 		BuildTags:        []string{"bt1", "bt2"},
-		Emulator:         []string{"be1", "be2"},
 		DefaultStackSize: 42,
 		AutoStackSize:    &baseAutoStackSize,
 	}
@@ -38,7 +37,6 @@ func TestOverrideProperties(t *testing.T) {
 		GOOS:             "",
 		CPU:              "chlidCpu",
 		CFlags:           []string{"-child-foo", "-child-bar"},
-		Emulator:         []string{"ce1", "ce2"},
 		AutoStackSize:    &childAutoStackSize,
 		DefaultStackSize: 64,
 	}
@@ -57,9 +55,6 @@ func TestOverrideProperties(t *testing.T) {
 	if !reflect.DeepEqual(base.BuildTags, []string{"bt1", "bt2"}) {
 		t.Errorf("Overriding failed : got %v", base.BuildTags)
 	}
-	if !reflect.DeepEqual(base.Emulator, []string{"ce1", "ce2"}) {
-		t.Errorf("Overriding failed : got %v", base.Emulator)
-	}
 	if *base.AutoStackSize != false {
 		t.Errorf("Overriding failed : got %v", base.AutoStackSize)
 	}