cgen: initialize globals with default initializer when none is given. (#10979)

cmd/tools/modules/testing/common.v

@@ -266,6 +266,10 @@ fn worker_trunner(mut p pool.PoolProcessor, idx int, thread_id int) voidptr {
 	tls_bench.no_cstep = true
 	dot_relative_file := p.get_item<string>(idx)
 	mut relative_file := dot_relative_file.replace('./', '')
+	mut cmd_options := [ts.vargs]
+	if relative_file.contains('global') && !ts.vargs.contains('fmt') {
+		cmd_options << ' -enable-globals'
+	}
 	if ts.root_relative {
 		relative_file = relative_file.replace(ts.vroot + os.path_separator, '')
 	}
@@ -285,7 +289,6 @@ fn worker_trunner(mut p pool.PoolProcessor, idx int, thread_id int) voidptr {
 			os.rm(generated_binary_fpath) or { panic(err) }
 		}
 	}
-	mut cmd_options := [ts.vargs]
 	if !ts.vargs.contains('fmt') {
 		cmd_options << ' -o "$generated_binary_fpath"'
 	}

vlib/v/gen/c/cgen.v

@@ -49,6 +49,7 @@ mut:
 	typedefs2              strings.Builder
 	type_definitions       strings.Builder // typedefs, defines etc (everything that goes to the top of the file)
 	definitions            strings.Builder // typedefs, defines etc (everything that goes to the top of the file)
+	global_initializations strings.Builder // default initializers for globals (goes in _vinit())
 	inits                  map[string]strings.Builder // contents of `void _vinit/2{}`
 	cleanups               map[string]strings.Builder // contents of `void _vcleanup(){}`
 	gowrappers             strings.Builder // all go callsite wrappers
@@ -205,6 +206,7 @@ pub fn gen(files []&ast.File, table &ast.Table, pref &pref.Preferences) string {
 		typedefs2: strings.new_builder(100)
 		type_definitions: strings.new_builder(100)
 		definitions: strings.new_builder(100)
+		global_initializations: strings.new_builder(100)
 		gowrappers: strings.new_builder(100)
 		stringliterals: strings.new_builder(100)
 		auto_str_funcs: strings.new_builder(100)
@@ -5115,7 +5117,15 @@ fn (mut g Gen) global_decl(node ast.GlobalDecl) {
 		if field.has_expr {
 			g.definitions.writeln('$mod$styp $field.name = $field.expr; // global')
 		} else {
-			g.definitions.writeln('$mod$styp $field.name; // global')
+			default_initializer := g.type_default(field.typ)
+			if default_initializer == '{0}' {
+				g.definitions.writeln('$mod$styp $field.name = {0}; // global')
+			} else {
+				g.definitions.writeln('$mod$styp $field.name; // global')
+				if field.name !in ['as_cast_type_indexes', 'g_memory_block'] {
+					g.global_initializations.writeln('\t$field.name = *($styp*)&(($styp[]){${g.type_default(field.typ)}}[0]); // global')
+				}
+			}
 		}
 	}
 }
@@ -5442,6 +5452,9 @@ fn (mut g Gen) write_init_function() {
 	g.writeln('\tbuiltin_init();')
 	g.writeln('\tvinit_string_literals();')
 	//
+	g.writeln('\t// Initializations for global variables with default initializers')
+	g.write(g.global_initializations.str())
+	//
 	for mod_name in g.table.modules {
 		g.writeln('\t// Initializations for module $mod_name :')
 		g.write(g.inits[mod_name].str())

vlib/v/tests/init_global_test.v

@@ -0,0 +1,33 @@
+fn one() int {
+	return 1
+}
+
+fn pushf64() {
+	ch <- 12.5
+}
+
+fn test_global_init() {
+	intmap['two'] = 27
+	key := 'two'
+	assert intmap[key] == 27
+	t := go pushf64()
+	numberfns['one'] = one
+	numberfns['two'] = fn () int {
+		return 2
+	}
+	f := numberfns['one']
+	n := f()
+	assert n == 1
+	m := numberfns['two']()
+	assert m == 2
+	got := <-ch
+	assert got == 12.5
+	t.wait()
+	assert true
+}
+
+__global (
+	intmap    map[string]int
+	numberfns map[string]fn () int
+	ch        chan f64
+)