From 1cb752f722dac37ebb57500f29c6e6053151af4e Mon Sep 17 00:00:00 2001
From: Hunam <hunam@disroot.org>
Date: Fri, 1 Jul 2022 14:52:43 +0200
Subject: [PATCH] preliminary support for builtin functions, various fixes,
 various tweaks

---
 cmd/tools/builders/go_builder.v               |  7 ++++++
 cmd/tools/builders/golang_builder.v           |  7 ------
 cmd/v/v.v                                     |  4 ++--
 vlib/builtin/go/builtin.go.v                  |  5 +++++
 vlib/v/ast/ast.v                              |  2 +-
 vlib/v/ast/types.v                            |  1 +
 vlib/v/builder/cc.v                           |  3 ++-
 vlib/v/builder/compile.v                      |  7 ++++--
 .../golangbuilder.v => gobuilder/gobuilder.v} | 22 +++++++++++++------
 vlib/v/checker/checker.v                      |  4 ++--
 vlib/v/checker/fn.v                           |  7 +++---
 vlib/v/gen/golang/golang.v                    | 18 +++++++++++----
 vlib/v/parser/parser.v                        | 12 +++++++++-
 vlib/v/pref/pref.v                            |  4 ++--
 14 files changed, 71 insertions(+), 32 deletions(-)
 create mode 100644 cmd/tools/builders/go_builder.v
 delete mode 100644 cmd/tools/builders/golang_builder.v
 create mode 100644 vlib/builtin/go/builtin.go.v
 rename vlib/v/builder/{golangbuilder/golangbuilder.v => gobuilder/gobuilder.v} (63%)

diff --git a/cmd/tools/builders/go_builder.v b/cmd/tools/builders/go_builder.v
new file mode 100644
index 0000000000..43a7a43592
--- /dev/null
+++ b/cmd/tools/builders/go_builder.v
@@ -0,0 +1,7 @@
+module main
+
+import v.builder.gobuilder
+
+fn main() {
+	gobuilder.start()
+}
diff --git a/cmd/tools/builders/golang_builder.v b/cmd/tools/builders/golang_builder.v
deleted file mode 100644
index d2b7edf1a6..0000000000
--- a/cmd/tools/builders/golang_builder.v
+++ /dev/null
@@ -1,7 +0,0 @@
-module main
-
-import v.builder.golangbuilder
-
-fn main() {
-	golangbuilder.start()
-}
diff --git a/cmd/v/v.v b/cmd/v/v.v
index 5b3cfbd936..4a304156dd 100644
--- a/cmd/v/v.v
+++ b/cmd/v/v.v
@@ -176,9 +176,9 @@ fn rebuild(prefs &pref.Preferences) {
 		.interpret {
 			util.launch_tool(prefs.is_verbose, 'builders/interpret_builder', os.args[1..])
 		}
-		.golang {
+		.@go {
 			println('using Go WIP backend...')
-			util.launch_tool(prefs.is_verbose, 'builders/golang_builder', os.args[1..])
+			util.launch_tool(prefs.is_verbose, 'builders/go_builder', os.args[1..])
 		}
 	}
 }
diff --git a/vlib/builtin/go/builtin.go.v b/vlib/builtin/go/builtin.go.v
new file mode 100644
index 0000000000..d4504c503f
--- /dev/null
+++ b/vlib/builtin/go/builtin.go.v
@@ -0,0 +1,5 @@
+module builtin
+
+pub fn println(s string) {
+	#fmt.Println(s.str)
+}
diff --git a/vlib/v/ast/ast.v b/vlib/v/ast/ast.v
index 5b2d122f6c..d738e6758c 100644
--- a/vlib/v/ast/ast.v
+++ b/vlib/v/ast/ast.v
@@ -523,7 +523,7 @@ pub:
 	method_idx      int
 	rec_mut         bool // is receiver mutable
 	rec_share       ShareType
-	language        Language  // V, C, JS
+	language        Language  // V, C, JS, Go
 	file_mode       Language  // whether *the file*, where a function was a '.c.v', '.js.v' etc.
 	no_body         bool      // just a definition `fn C.malloc()`
 	is_builtin      bool      // this function is defined in builtin/strconv
diff --git a/vlib/v/ast/types.v b/vlib/v/ast/types.v
index d82d1bd167..71b4eb552c 100644
--- a/vlib/v/ast/types.v
+++ b/vlib/v/ast/types.v
@@ -35,6 +35,7 @@ pub enum Language {
 	v
 	c
 	js
+	@go
 	amd64 // aka x86_64
 	i386
 	arm64 // 64-bit arm
diff --git a/vlib/v/builder/cc.v b/vlib/v/builder/cc.v
index f3a487eb51..30a1c80bf9 100644
--- a/vlib/v/builder/cc.v
+++ b/vlib/v/builder/cc.v
@@ -523,7 +523,8 @@ pub fn (mut v Builder) cc() {
 	// whether to just create a .c or .js file and exit, for example: `v -o v.c cmd.v`
 	ends_with_c := v.pref.out_name.ends_with('.c')
 	ends_with_js := v.pref.out_name.ends_with('.js')
-	if ends_with_c || ends_with_js {
+	ends_with_go := v.pref.out_name.ends_with('.go')
+	if ends_with_c || ends_with_js || ends_with_go {
 		v.pref.skip_running = true
 		msg_mv := 'os.mv_by_cp $v.out_name_c => $v.pref.out_name'
 		util.timing_start(msg_mv)
diff --git a/vlib/v/builder/compile.v b/vlib/v/builder/compile.v
index 828e397704..d0afb65ced 100644
--- a/vlib/v/builder/compile.v
+++ b/vlib/v/builder/compile.v
@@ -88,7 +88,7 @@ fn (mut b Builder) run_compiled_executable_and_exit() {
 		os.find_abs_path_of_executable(node_basename) or {
 			panic('Could not find `$node_basename` in system path. Do you have Node.js installed?')
 		}
-	} else if b.pref.backend == .golang {
+	} else if b.pref.backend == .@go {
 		go_basename := $if windows { 'go.exe' } $else { 'go' }
 		os.find_abs_path_of_executable(go_basename) or {
 			panic('Could not find `$go_basename` in system path. Do you have Go installed?')
@@ -99,7 +99,7 @@ fn (mut b Builder) run_compiled_executable_and_exit() {
 	mut run_args := []string{cap: b.pref.run_args.len + 1}
 	if b.pref.backend.is_js() {
 		run_args << compiled_file
-	} else if b.pref.backend == .golang {
+	} else if b.pref.backend == .@go {
 		run_args << ['run', compiled_file]
 	}
 	run_args << b.pref.run_args
@@ -195,6 +195,9 @@ pub fn (v Builder) get_builtin_files() []string {
 			if v.pref.backend.is_js() {
 				builtin_files << v.v_files_from_dir(os.join_path(location, 'builtin',
 					'js'))
+			} else if v.pref.backend == .@go {
+				builtin_files << v.v_files_from_dir(os.join_path(location, 'builtin',
+					'go'))
 			} else {
 				builtin_files << v.v_files_from_dir(os.join_path(location, 'builtin'))
 			}
diff --git a/vlib/v/builder/golangbuilder/golangbuilder.v b/vlib/v/builder/gobuilder/gobuilder.v
similarity index 63%
rename from vlib/v/builder/golangbuilder/golangbuilder.v
rename to vlib/v/builder/gobuilder/gobuilder.v
index 79cae393e9..ce47b36a72 100644
--- a/vlib/v/builder/golangbuilder/golangbuilder.v
+++ b/vlib/v/builder/gobuilder/gobuilder.v
@@ -1,4 +1,4 @@
-module golangbuilder
+module gobuilder
 
 import os
 import v.pref
@@ -9,17 +9,25 @@ import v.gen.golang
 pub fn start() {
 	mut args_and_flags := util.join_env_vflags_and_os_args()[1..]
 	prefs, _ := pref.parse_args([], args_and_flags)
-	builder.compile('build', prefs, compile_golang)
+	builder.compile('build', prefs, compile_go)
 }
 
-pub fn compile_golang(mut b builder.Builder) {
-	// v.files << v.v_files_from_dir(os.join_path(v.pref.vlib_path,'builtin','bare'))
-	files := [b.pref.path]
+pub fn compile_go(mut b builder.Builder) {
+	mut files := b.get_builtin_files()
+	files << b.get_user_files()
 	b.set_module_lookup_paths()
-	build_golang(mut b, files, b.pref.out_name)
+	if b.pref.is_verbose {
+		println('all .v files:')
+		println(files)
+	}
+	mut name := b.pref.out_name
+	if !name.ends_with('.go') {
+		name += '.go'
+	}
+	build_go(mut b, files, name)
 }
 
-pub fn build_golang(mut b builder.Builder, v_files []string, out_file string) {
+pub fn build_go(mut b builder.Builder, v_files []string, out_file string) {
 	if b.pref.os == .windows {
 		if !b.pref.is_shared && b.pref.build_mode != .build_module
 			&& !b.pref.out_name.ends_with('.exe') {
diff --git a/vlib/v/checker/checker.v b/vlib/v/checker/checker.v
index 7f372a7e50..eea829fce9 100644
--- a/vlib/v/checker/checker.v
+++ b/vlib/v/checker/checker.v
@@ -1765,14 +1765,14 @@ fn (mut c Checker) hash_stmt(mut node ast.HashStmt) {
 	if c.ct_cond_stack.len > 0 {
 		node.ct_conds = c.ct_cond_stack.clone()
 	}
-	if c.pref.backend.is_js() || c.pref.backend == .golang {
+	if c.pref.backend.is_js() || c.pref.backend == .@go {
 		// consider the the best way to handle the .go.vv files
 		if !c.file.path.ends_with('.js.v') && !c.file.path.ends_with('.go.v')
 			&& !c.file.path.ends_with('.go.vv') {
 			c.error('hash statements are only allowed in backend specific files such "x.js.v" and "x.go.v"',
 				node.pos)
 		}
-		if c.mod == 'main' && c.pref.backend != .golang {
+		if c.mod == 'main' && c.pref.backend != .@go {
 			c.error('hash statements are not allowed in the main module. Place them in a separate module.',
 				node.pos)
 		}
diff --git a/vlib/v/checker/fn.v b/vlib/v/checker/fn.v
index bbb503408a..55b25c2b3a 100644
--- a/vlib/v/checker/fn.v
+++ b/vlib/v/checker/fn.v
@@ -438,7 +438,7 @@ pub fn (mut c Checker) call_expr(mut node ast.CallExpr) ast.Type {
 
 pub fn (mut c Checker) fn_call(mut node ast.CallExpr, mut continue_check &bool) ast.Type {
 	fn_name := node.name
-	if fn_name == 'main' {
+	if fn_name == 'main' && node.language != .@go {
 		c.error('the `main` function cannot be called in the program', node.pos)
 	}
 	mut has_generic := false // foo<T>() instead of foo<int>()
@@ -1292,8 +1292,9 @@ pub fn (mut c Checker) method_call(mut node ast.CallExpr) ast.Type {
 		} else {
 			c.fail_if_unreadable(node.left, left_type, 'receiver')
 		}
-		if left_sym.language != .js && (!left_sym.is_builtin() && method.mod != 'builtin')
-			&& method.language == .v && method.no_body {
+		if left_sym.language != .js && left_sym.language != .@go
+			&& (!left_sym.is_builtin() && method.mod != 'builtin') && method.language == .v
+			&& method.no_body {
 			c.error('cannot call a method that does not have a body', node.pos)
 		}
 		if node.concrete_types.len > 0 && method.generic_names.len > 0
diff --git a/vlib/v/gen/golang/golang.v b/vlib/v/gen/golang/golang.v
index b7ac957c1b..e990c67d77 100644
--- a/vlib/v/gen/golang/golang.v
+++ b/vlib/v/gen/golang/golang.v
@@ -10,9 +10,10 @@ import v.pref
 import os
 
 const (
-	bs      = '\\'
+	bs            = '\\'
 	// when to break a line dependant on penalty
-	max_len = [0, 35, 60, 85, 93, 100]
+	max_len       = [0, 35, 60, 85, 93, 100]
+	v_builtin_fns = ['println', 'print', 'eprintln', 'eprint', 'exit', 'panic']
 )
 
 pub struct Gen {
@@ -867,6 +868,7 @@ pub fn (mut f Gen) expr_stmt(node ast.ExprStmt) {
 }
 
 pub fn (mut f Gen) enum_decl(node ast.EnumDecl) {
+	// TODO(hunam6): transform to custom type + iota
 	f.attrs(node.attrs)
 	if node.is_pub {
 		f.write('pub ')
@@ -889,8 +891,15 @@ pub fn (mut f Gen) enum_decl(node ast.EnumDecl) {
 }
 
 pub fn (mut f Gen) fn_decl(node ast.FnDecl) {
-	f.attrs(node.attrs)
-	f.write(node.stringify(f.table, f.cur_mod, f.mod2alias).replace('fn ', 'func '))
+	v_fn_signature := node.stringify(f.table, f.cur_mod, f.mod2alias)
+	before_name_idx := v_fn_signature.index('fn') or { 0 } + 3 // will never equal 0
+	after_name_idx := v_fn_signature.index('(') or { 0 } // will never equal 0
+	mut name := v_fn_signature[before_name_idx..after_name_idx]
+	if v_fn_signature[..3] == 'pub' && name !in golang.v_builtin_fns {
+		name = name.capitalize()
+	}
+
+	f.write('func $name${v_fn_signature[after_name_idx..]}')
 	f.fn_body(node)
 }
 
@@ -1124,6 +1133,7 @@ pub fn (mut f Gen) interface_method(method ast.FnDecl) {
 }
 
 pub fn (mut f Gen) module_stmt(mod ast.Module) {
+	dump(mod)
 	f.set_current_module_name(mod.name)
 	if mod.is_skipped {
 		return
diff --git a/vlib/v/parser/parser.v b/vlib/v/parser/parser.v
index f7122bb45f..9d1acc9428 100644
--- a/vlib/v/parser/parser.v
+++ b/vlib/v/parser/parser.v
@@ -203,6 +203,9 @@ pub fn (mut p Parser) set_path(path string) {
 		'js' {
 			p.file_backend_mode = .js
 		}
+		'go' {
+			p.file_backend_mode = .@go
+		}
 		else {
 			arch := pref.arch_from_string(actual_language) or { pref.Arch._auto }
 			p.file_backend_mode = ast.pref_arch_to_table_language(arch)
@@ -3096,7 +3099,7 @@ fn (mut p Parser) module_decl() ast.Module {
 	mut module_pos := token.Pos{}
 	mut name_pos := token.Pos{}
 	mut mod_node := ast.Module{}
-	is_skipped := p.tok.kind != .key_module
+	mut is_skipped := p.tok.kind != .key_module
 	if is_skipped {
 		// the attributes were for something else != module, like a struct/fn/type etc.
 		module_attrs = []
@@ -3133,6 +3136,13 @@ fn (mut p Parser) module_decl() ast.Module {
 	full_name := util.qualify_module(p.pref, name, p.file_name)
 	p.mod = full_name
 	p.builtin_mod = p.mod == 'builtin'
+	dump(p.builtin_mod)
+	dump(p.file_backend_mode)
+	dump(p.language)
+	// NOTE: Not so sure about that
+	if p.builtin_mod && p.file_backend_mode == .@go {
+		is_skipped = true
+	}
 	mod_node = ast.Module{
 		name: full_name
 		short_name: name
diff --git a/vlib/v/pref/pref.v b/vlib/v/pref/pref.v
index 5b2440957a..de602eb8b2 100644
--- a/vlib/v/pref/pref.v
+++ b/vlib/v/pref/pref.v
@@ -51,7 +51,7 @@ pub enum Backend {
 	js_freestanding // The JavaScript freestanding backend
 	native // The Native backend
 	interpret // Interpret the ast
-	golang // Go backend
+	@go // Go backend
 }
 
 pub fn (b Backend) is_js() bool {
@@ -922,7 +922,7 @@ pub fn backend_from_string(s string) ?Backend {
 	match s {
 		'c' { return .c }
 		'js' { return .js_node }
-		'go' { return .golang }
+		'go' { return .@go }
 		'js_node' { return .js_node }
 		'js_browser' { return .js_browser }
 		'js_freestanding' { return .js_freestanding }