add new and init to toolchain

compiler/build.odin

@@ -11,6 +11,8 @@ import "./target"
 import "./types"
 import "core:fmt"
 import vmem "core:mem/virtual"
+import "core:os"
+import "core:os/os2"
 import "core:path/filepath"
 import "core:strings"
 
@@ -46,6 +48,21 @@ destroy_build_config :: proc(cfg: ^BuildConfig) {
 // package the config names. build.bro is only checked (never lowered/emitted),
 // so the config is read straight from the HIR.
 run_build :: proc(root: string) -> int {
+	project_root := root
+	owns_project_root := false
+	if len(project_root) == 0 {
+		found_root, found := find_build_root()
+		if !found {
+			fmt.eprintln("brolang build: could not find build.bro in the current directory or any parent")
+			return 2
+		}
+		project_root = found_root
+		owns_project_root = true
+	}
+	defer if owns_project_root {
+		delete(project_root)
+	}
+
 	sources := source.init_store()
 	defer source.destroy_store(&sources)
 	diagnostics := source.init_store_diagnostics(&sources)
@@ -61,10 +78,10 @@ run_build :: proc(root: string) -> int {
 	defer vmem.arena_destroy(&arena)
 	a := vmem.arena_allocator(&arena)
 
-	ast_module, loaded := loader.load(root, &sources, &diagnostics, &symbols, a, a, cimport.Options{}, target.DEFAULT)
+	ast_module, loaded := loader.load(project_root, &sources, &diagnostics, &symbols, a, a, cimport.Options{}, target.DEFAULT, project_root)
 	if !loaded {
 		source.print_all(&diagnostics)
-		fmt.eprintln("failed to load build root:", root)
+		fmt.eprintln("failed to load build root:", project_root)
 		return 2
 	}
 	// check needs no `main`: it synthesizes a trap main and emits one benign
@@ -82,9 +99,81 @@ run_build :: proc(root: string) -> int {
 	}
 	defer destroy_build_config(&cfg)
 
-	program := filepath.join({root, cfg.source_dir})
+	program := filepath.join({project_root, cfg.source_dir})
 	defer delete(program)
-	return compile_package(program, cfg.output_name, cfg.link_arguments, target.DEFAULT, cfg.c_options)
+	output, output_ok := build_output_path(project_root, cfg.output_name)
+	if !output_ok {
+		return 2
+	}
+	defer delete(output)
+	return compile_package(program, output, cfg.link_arguments, target.DEFAULT, cfg.c_options, project_root)
+}
+
+valid_output_name :: proc(name: string) -> bool {
+	return len(name) > 0 && name != "." && name != ".." &&
+	       !strings.contains(name, "/") && !strings.contains(name, "\\")
+}
+
+build_output_path :: proc(project_root, name: string, allocator := context.allocator) -> (string, bool) {
+	if !valid_output_name(name) {
+		fmt.eprintfln("build.bro: config 'name' must be a plain executable name, got '%s'", name)
+		return "", false
+	}
+	build_dir, dir_error := filepath.join({project_root, "build"}, allocator)
+	if dir_error != nil {
+		return "", false
+	}
+	if err := os2.make_directory_all(build_dir); err != nil {
+		fmt.eprintfln("failed to create build directory '%s': %v", build_dir, err)
+		delete(build_dir, allocator)
+		return "", false
+	}
+	output, output_error := filepath.join({build_dir, name}, allocator)
+	delete(build_dir, allocator)
+	if output_error != nil {
+		return "", false
+	}
+	return output, true
+}
+
+find_build_root :: proc(allocator := context.allocator) -> (string, bool) {
+	current := os.get_current_directory(allocator)
+	if len(current) == 0 {
+		return "", false
+	}
+	defer delete(current, allocator)
+	return find_build_root_from(current, allocator)
+}
+
+find_build_root_from :: proc(start: string, allocator := context.allocator) -> (string, bool) {
+	current, current_ok := filepath.abs(start, allocator)
+	if !current_ok {
+		current = strings.clone(start, allocator)
+	}
+	for {
+		build_path, build_error := filepath.join({current, "build.bro"}, allocator)
+		if build_error != nil {
+			delete(current, allocator)
+			return "", false
+		}
+		found := os.exists(build_path)
+		delete(build_path, allocator)
+		if found {
+			return current, true
+		}
+		if current == "/" {
+			delete(current, allocator)
+			return "", false
+		}
+		parent := filepath.dir(current, allocator)
+		if parent == current {
+			delete(parent, allocator)
+			delete(current, allocator)
+			return "", false
+		}
+		delete(current, allocator)
+		current = parent
+	}
 }
 
 // build_bro_has_errors reports whether checking build.bro produced any diagnostic