compileopts: silently succeed when there's no debug info to strip

Before, on the baremetal target or MacOS, we errored if the user
provided configuration to strip debug info.

Ex.
```bash
$ $ tinygo build -o main.go  -scheduler=none --no-debug  main.go
error: cannot remove debug information: MacOS doesn't store debug info in the executable by default
```

This is a poor experience which results in having OS-specific CLI
behavior. Silently succeeding is good keeping with the Linux philosophy
and less distracting than logging the same without failing.

Signed-off-by: Adrian Cole <adrian@tetrate.io>

builder/build.go

@@ -700,21 +700,25 @@ func Build(pkgName, outpath string, config *compileopts.Config, action func(Buil
 	// Add embedded files.
 	linkerDependencies = append(linkerDependencies, embedFileObjects...)
 
+	// Determine whether the compilation configuration would result in debug
+	// (DWARF) information in the object files.
+	var hasDebug = true
+	for _, tag := range config.BuildTags() {
+		if tag == "baremetal" {
+			// Don't use -no-debug on baremetal targets. It makes no sense:
+			// the debug information isn't flashed to the device anyway.
+			hasDebug = false
+		}
+	}
+	if config.GOOS() == "darwin" {
+		// Debug information isn't stored in the binary itself on MacOS but
+		// is left in the object files by default. The binary does store the
+		// path to these object files though.
+		hasDebug = false
+	}
+
 	// Strip debug information with -no-debug.
-	if !config.Debug() {
+	if hasDebug && !config.Debug() {
-		for _, tag := range config.BuildTags() {
-			if tag == "baremetal" {
-				// Don't use -no-debug on baremetal targets. It makes no sense:
-				// the debug information isn't flashed to the device anyway.
-				return fmt.Errorf("stripping debug information is unnecessary for baremetal targets")
-			}
-		}
-		if config.GOOS() == "darwin" {
-			// Debug information isn't stored in the binary itself on MacOS but
-			// is left in the object files by default. The binary does store the
-			// path to these object files though.
-			return errors.New("cannot remove debug information: MacOS doesn't store debug info in the executable by default")
-		}
 		if config.Target.Linker == "wasm-ld" {
 			// Don't just strip debug information, also compress relocations
 			// while we're at it. Relocations can only be compressed when debug

compileopts/config.go

@@ -377,8 +377,8 @@ func (c *Config) VerifyIR() bool {
 }
 
 // Debug returns whether debug (DWARF) information should be retained by the
-// linker. By default, debug information is retained but it can be removed with
+// linker. By default, debug information is retained, but it can be removed
-// the -no-debug flag.
+// with the -no-debug flag.
 func (c *Config) Debug() bool {
 	return c.Options.Debug
 }