builder: refactor Build function to not use a callback

The only reason a callback was used, was so that the temporary directory
gets removed once `Build` returns. But that is honestly a really bad
reason: the parent function can simply create a temporary function and
remove it when it returns. It wasn't worth the code complexity that this
callback created.

This change should not cause any observable differences in behavior (it
should be a non-functional change).

I have no reason to do this now, but this unclean code has been bugging
me and I just wanted to get it fixed.

1 files changed, 48 insertions, 55 deletions

diff --git a/builder/build.go b/builder/build.go
index 478d8a733..8095a6b60 100644
--- a/builder/build.go
+++ b/builder/build.go
@@ -42,8 +42,8 @@ type BuildResult struct {
 	// information. Used for GDB for example.
 	Executable string
 
-	// A path to the output binary. It will be removed after Build returns, so
-	// if it should be kept it must be copied or moved away.
+	// A path to the output binary. It is stored in the tmpdir directory of the
+	// Build function, so if it should be kept it must be copied or moved away.
 	// It is often the same as Executable, but differs if the output format is
 	// .hex for example (instead of the usual ELF).
 	Binary string
@@ -94,23 +94,16 @@ type packageAction struct {
 //
 // The error value may be of type *MultiError. Callers will likely want to check
 // for this case and print such errors individually.
-func Build(pkgName, outpath string, config *compileopts.Config, action func(BuildResult) error) error {
+func Build(pkgName, outpath, tmpdir string, config *compileopts.Config) (BuildResult, error) {
 	// Read the build ID of the tinygo binary.
 	// Used as a cache key for package builds.
 	compilerBuildID, err := ReadBuildID()
 	if err != nil {
-		return err
+		return BuildResult{}, err
 	}
 
-	// Create a temporary directory for intermediary files.
-	dir, err := os.MkdirTemp("", "tinygo")
-	if err != nil {
-		return err
-	}
 	if config.Options.Work {
-		fmt.Printf("WORK=%s\n", dir)
-	} else {
-		defer os.RemoveAll(dir)
+		fmt.Printf("WORK=%s\n", tmpdir)
 	}
 
 	// Look up the build cache directory, which is used to speed up incremental
@@ -119,7 +112,7 @@ func Build(pkgName, outpath string, config *compileopts.Config, action func(Buil
 	if cacheDir == "off" {
 		// Use temporary build directory instead, effectively disabling the
 		// build cache.
-		cacheDir = dir
+		cacheDir = tmpdir
 	}
 
 	// Check for a libc dependency.
@@ -129,40 +122,40 @@ func Build(pkgName, outpath string, config *compileopts.Config, action func(Buil
 	var libcDependencies []*compileJob
 	switch config.Target.Libc {
 	case "darwin-libSystem":
-		job := makeDarwinLibSystemJob(config, dir)
+		job := makeDarwinLibSystemJob(config, tmpdir)
 		libcDependencies = append(libcDependencies, job)
 	case "musl":
-		job, unlock, err := Musl.load(config, dir)
+		job, unlock, err := Musl.load(config, tmpdir)
 		if err != nil {
-			return err
+			return BuildResult{}, err
 		}
 		defer unlock()
 		libcDependencies = append(libcDependencies, dummyCompileJob(filepath.Join(filepath.Dir(job.result), "crt1.o")))
 		libcDependencies = append(libcDependencies, job)
 	case "picolibc":
-		libcJob, unlock, err := Picolibc.load(config, dir)
+		libcJob, unlock, err := Picolibc.load(config, tmpdir)
 		if err != nil {
-			return err
+			return BuildResult{}, err
 		}
 		defer unlock()
 		libcDependencies = append(libcDependencies, libcJob)
 	case "wasi-libc":
 		path := filepath.Join(root, "lib/wasi-libc/sysroot/lib/wasm32-wasi/libc.a")
 		if _, err := os.Stat(path); errors.Is(err, fs.ErrNotExist) {
-			return errors.New("could not find wasi-libc, perhaps you need to run `make wasi-libc`?")
+			return BuildResult{}, errors.New("could not find wasi-libc, perhaps you need to run `make wasi-libc`?")
 		}
 		libcDependencies = append(libcDependencies, dummyCompileJob(path))
 	case "mingw-w64":
-		_, unlock, err := MinGW.load(config, dir)
+		_, unlock, err := MinGW.load(config, tmpdir)
 		if err != nil {
-			return err
+			return BuildResult{}, err
 		}
 		unlock()
-		libcDependencies = append(libcDependencies, makeMinGWExtraLibs(dir)...)
+		libcDependencies = append(libcDependencies, makeMinGWExtraLibs(tmpdir)...)
 	case "":
 		// no library specified, so nothing to do
 	default:
-		return fmt.Errorf("unknown libc: %s", config.Target.Libc)
+		return BuildResult{}, fmt.Errorf("unknown libc: %s", config.Target.Libc)
 	}
 
 	optLevel, sizeLevel, _ := config.OptLevels()
@@ -188,7 +181,7 @@ func Build(pkgName, outpath string, config *compileopts.Config, action func(Buil
 	// address spaces, etc).
 	machine, err := compiler.NewTargetMachine(compilerConfig)
 	if err != nil {
-		return err
+		return BuildResult{}, err
 	}
 	defer machine.Dispose()
 
@@ -197,11 +190,11 @@ func Build(pkgName, outpath string, config *compileopts.Config, action func(Buil
 		Sizes: compiler.Sizes(machine),
 	})
 	if err != nil {
-		return err
+		return BuildResult{}, err
 	}
 	err = lprogram.Parse()
 	if err != nil {
-		return err
+		return BuildResult{}, err
 	}
 
 	// Create the *ssa.Program. This does not yet build the entire SSA of the
@@ -270,7 +263,7 @@ func Build(pkgName, outpath string, config *compileopts.Config, action func(Buil
 						}
 					}
 
-					job.result, err = createEmbedObjectFile(string(data), hexSum, name, pkg.OriginalDir(), dir, compilerConfig)
+					job.result, err = createEmbedObjectFile(string(data), hexSum, name, pkg.OriginalDir(), tmpdir, compilerConfig)
 					return err
 				},
 			}
@@ -284,7 +277,7 @@ func Build(pkgName, outpath string, config *compileopts.Config, action func(Buil
 		for _, imported := range pkg.Pkg.Imports() {
 			job, ok := packageActionIDJobs[imported.Path()]
 			if !ok {
-				return fmt.Errorf("package %s imports %s but couldn't find dependency", pkg.ImportPath, imported.Path())
+				return BuildResult{}, fmt.Errorf("package %s imports %s but couldn't find dependency", pkg.ImportPath, imported.Path())
 			}
 			importedPackages = append(importedPackages, job)
 			actionIDDependencies = append(actionIDDependencies, job)
@@ -370,7 +363,7 @@ func Build(pkgName, outpath string, config *compileopts.Config, action func(Buil
 				// Packages are compiled independently anyway.
 				for _, cgoHeader := range pkg.CGoHeaders {
 					// Store the header text in a temporary file.
-					f, err := os.CreateTemp(dir, "cgosnippet-*.c")
+					f, err := os.CreateTemp(tmpdir, "cgosnippet-*.c")
 					if err != nil {
 						return err
 					}
@@ -579,17 +572,17 @@ func Build(pkgName, outpath string, config *compileopts.Config, action func(Buil
 		// Run jobs to produce the LLVM module.
 		err := runJobs(programJob, config.Options.Semaphore)
 		if err != nil {
-			return err
+			return BuildResult{}, err
 		}
 		// Generate output.
 		switch outext {
 		case ".o":
 			llvmBuf, err := machine.EmitToMemoryBuffer(mod, llvm.ObjectFile)
 			if err != nil {
-				return err
+				return BuildResult{}, err
 			}
 			defer llvmBuf.Dispose()
-			return os.WriteFile(outpath, llvmBuf.Bytes(), 0666)
+			return BuildResult{}, os.WriteFile(outpath, llvmBuf.Bytes(), 0666)
 		case ".bc":
 			var buf llvm.MemoryBuffer
 			if config.UseThinLTO() {
@@ -598,10 +591,10 @@ func Build(pkgName, outpath string, config *compileopts.Config, action func(Buil
 				buf = llvm.WriteBitcodeToMemoryBuffer(mod)
 			}
 			defer buf.Dispose()
-			return os.WriteFile(outpath, buf.Bytes(), 0666)
+			return BuildResult{}, os.WriteFile(outpath, buf.Bytes(), 0666)
 		case ".ll":
 			data := []byte(mod.String())
-			return os.WriteFile(outpath, data, 0666)
+			return BuildResult{}, os.WriteFile(outpath, data, 0666)
 		default:
 			panic("unreachable")
 		}
@@ -612,7 +605,7 @@ func Build(pkgName, outpath string, config *compileopts.Config, action func(Buil
 	// run all jobs in parallel as far as possible.
 
 	// Add job to write the output object file.
-	objfile := filepath.Join(dir, "main.o")
+	objfile := filepath.Join(tmpdir, "main.o")
 	outputObjectFileJob := &compileJob{
 		description:  "generate output file",
 		dependencies: []*compileJob{programJob},
@@ -635,7 +628,7 @@ func Build(pkgName, outpath string, config *compileopts.Config, action func(Buil
 
 	// Prepare link command.
 	linkerDependencies := []*compileJob{outputObjectFileJob}
-	executable := filepath.Join(dir, "main")
+	executable := filepath.Join(tmpdir, "main")
 	if config.GOOS() == "windows" {
 		executable += ".exe"
 	}
@@ -645,9 +638,9 @@ func Build(pkgName, outpath string, config *compileopts.Config, action func(Buil
 	// Add compiler-rt dependency if needed. Usually this is a simple load from
 	// a cache.
 	if config.Target.RTLib == "compiler-rt" {
-		job, unlock, err := CompilerRT.load(config, dir)
+		job, unlock, err := CompilerRT.load(config, tmpdir)
 		if err != nil {
-			return err
+			return BuildResult{}, err
 		}
 		defer unlock()
 		linkerDependencies = append(linkerDependencies, job)
@@ -661,7 +654,7 @@ func Build(pkgName, outpath string, config *compileopts.Config, action func(Buil
 		job := &compileJob{
 			description: "compile extra file " + path,
 			run: func(job *compileJob) error {
-				result, err := compileAndCacheCFile(abspath, dir, config.CFlags(), config.UseThinLTO(), config.Options.PrintCommands)
+				result, err := compileAndCacheCFile(abspath, tmpdir, config.CFlags(), config.UseThinLTO(), config.Options.PrintCommands)
 				job.result = result
 				return err
 			},
@@ -679,7 +672,7 @@ func Build(pkgName, outpath string, config *compileopts.Config, action func(Buil
 			job := &compileJob{
 				description: "compile CGo file " + abspath,
 				run: func(job *compileJob) error {
-					result, err := compileAndCacheCFile(abspath, dir, pkg.CFlags, config.UseThinLTO(), config.Options.PrintCommands)
+					result, err := compileAndCacheCFile(abspath, tmpdir, pkg.CFlags, config.UseThinLTO(), config.Options.PrintCommands)
 					job.result = result
 					return err
 				},
@@ -722,7 +715,7 @@ func Build(pkgName, outpath string, config *compileopts.Config, action func(Buil
 			ldflags = append(ldflags, "--strip-debug")
 		} else {
 			// Other linkers may have different flags.
-			return errors.New("cannot remove debug information: unknown linker: " + config.Target.Linker)
+			return BuildResult{}, errors.New("cannot remove debug information: unknown linker: " + config.Target.Linker)
 		}
 	}
 
@@ -879,7 +872,7 @@ func Build(pkgName, outpath string, config *compileopts.Config, action func(Buil
 	// is simpler and cannot be parallelized.
 	err = runJobs(linkJob, config.Options.Semaphore)
 	if err != nil {
-		return err
+		return BuildResult{}, err
 	}
 
 	// Get an Intel .hex file or .bin file from the .elf file.
@@ -890,40 +883,40 @@ func Build(pkgName, outpath string, config *compileopts.Config, action func(Buil
 	case "hex", "bin":
 		// Extract raw binary, either encoding it as a hex file or as a raw
 		// firmware file.
-		tmppath = filepath.Join(dir, "main"+outext)
+		tmppath = filepath.Join(tmpdir, "main"+outext)
 		err := objcopy(executable, tmppath, outputBinaryFormat)
 		if err != nil {
-			return err
+			return BuildResult{}, err
 		}
 	case "uf2":
 		// Get UF2 from the .elf file.
-		tmppath = filepath.Join(dir, "main"+outext)
+		tmppath = filepath.Join(tmpdir, "main"+outext)
 		err := convertELFFileToUF2File(executable, tmppath, config.Target.UF2FamilyID)
 		if err != nil {
-			return err
+			return BuildResult{}, err
 		}
 	case "esp32", "esp32-img", "esp32c3", "esp8266":
 		// Special format for the ESP family of chips (parsed by the ROM
 		// bootloader).
-		tmppath = filepath.Join(dir, "main"+outext)
+		tmppath = filepath.Join(tmpdir, "main"+outext)
 		err := makeESPFirmareImage(executable, tmppath, outputBinaryFormat)
 		if err != nil {
-			return err
+			return BuildResult{}, err
 		}
 	case "nrf-dfu":
 		// special format for nrfutil for Nordic chips
-		tmphexpath := filepath.Join(dir, "main.hex")
+		tmphexpath := filepath.Join(tmpdir, "main.hex")
 		err := objcopy(executable, tmphexpath, "hex")
 		if err != nil {
-			return err
+			return BuildResult{}, err
 		}
-		tmppath = filepath.Join(dir, "main"+outext)
+		tmppath = filepath.Join(tmpdir, "main"+outext)
 		err = makeDFUFirmwareImage(config.Options, tmphexpath, tmppath)
 		if err != nil {
-			return err
+			return BuildResult{}, err
 		}
 	default:
-		return fmt.Errorf("unknown output binary format: %s", outputBinaryFormat)
+		return BuildResult{}, fmt.Errorf("unknown output binary format: %s", outputBinaryFormat)
 	}
 
 	// If there's a module root, use that.
@@ -933,13 +926,13 @@ func Build(pkgName, outpath string, config *compileopts.Config, action func(Buil
 		moduleroot = lprogram.MainPkg().Root
 	}
 
-	return action(BuildResult{
+	return BuildResult{
 		Executable: executable,
 		Binary:     tmppath,
 		MainDir:    lprogram.MainPkg().Dir,
 		ModuleRoot: moduleroot,
 		ImportPath: lprogram.MainPkg().ImportPath,
-	})
+	}, nil
 }
 
 // createEmbedObjectFile creates a new object file with the given contents, for