cgen: properly handle initialization expression for globals (#10981)

vlib/v/ast/ast.v

@@ -535,11 +535,11 @@ pub:
 pub struct GlobalField {
 pub:
 	name     string
-	expr     Expr
 	has_expr bool
 	pos      token.Position
 	typ_pos  token.Position
 pub mut:
+	expr     Expr
 	typ      Type
 	comments []Comment
 }

vlib/v/ast/table.v

@@ -26,6 +26,7 @@ pub mut:
 	is_fmt             bool
 	used_fns           map[string]bool // filled in by the checker, when pref.skip_unused = true;
 	used_consts        map[string]bool // filled in by the checker, when pref.skip_unused = true;
+	used_globals       map[string]bool // filled in by the checker, when pref.skip_unused = true;
 	used_vweb_types    []Type // vweb context types, filled in by checker, when pref.skip_unused = true;
 	used_maps          int    // how many times maps were used, filled in by checker, when pref.skip_unused = true;
 	panic_handler      FnPanicHandler = default_table_panic_handler
@@ -52,6 +53,7 @@ pub fn (t &Table) free() {
 		t.cmod_prefix.free()
 		t.used_fns.free()
 		t.used_consts.free()
+		t.used_globals.free()
 		t.used_vweb_types.free()
 	}
 }

vlib/v/checker/checker.v

@@ -4544,7 +4544,7 @@ fn (mut c Checker) stmt(node ast.Stmt) {
 			c.for_stmt(mut node)
 		}
 		ast.GlobalDecl {
-			c.global_decl(node)
+			c.global_decl(mut node)
 		}
 		ast.GotoLabel {}
 		ast.GotoStmt {
@@ -4793,8 +4793,8 @@ fn (mut c Checker) for_stmt(mut node ast.ForStmt) {
 	c.in_for_count--
 }
 
-fn (mut c Checker) global_decl(node ast.GlobalDecl) {
-	for field in node.fields {
+fn (mut c Checker) global_decl(mut node ast.GlobalDecl) {
+	for mut field in node.fields {
 		c.check_valid_snake_case(field.name, 'global name', field.pos)
 		if field.name in c.global_names {
 			c.error('duplicate global `$field.name`', field.pos)
@@ -4803,6 +4803,14 @@ fn (mut c Checker) global_decl(node ast.GlobalDecl) {
 		if sym.kind == .placeholder {
 			c.error('unknown type `$sym.name`', field.typ_pos)
 		}
+		if field.expr !is ast.EmptyExpr {
+			expr_typ := c.expr(field.expr)
+			if !c.check_types(expr_typ, field.typ) {
+				got_sym := c.table.get_type_symbol(expr_typ)
+				c.error('cannot initialize global variable `$field.name` of type `$sym.name` with expression of type `$got_sym.name`',
+					field.expr.position())
+			}
+		}
 		c.global_names << field.name
 	}
 }

vlib/v/gen/c/cgen.v

@@ -5113,9 +5113,18 @@ fn (mut g Gen) const_decl_init_later(mod string, name string, expr ast.Expr, typ
 fn (mut g Gen) global_decl(node ast.GlobalDecl) {
 	mod := if g.pref.build_mode == .build_module && g.is_builtin_mod { 'static ' } else { '' }
 	for field in node.fields {
+		if g.pref.skip_unused {
+			if field.name !in g.table.used_globals {
+				$if trace_skip_unused_globals ? {
+					eprintln('>> skipping unused global name: $field.name')
+				}
+				continue
+			}
+		}
 		styp := g.typ(field.typ)
 		if field.has_expr {
-			g.definitions.writeln('$mod$styp $field.name = $field.expr; // global')
+			g.definitions.writeln('$mod$styp $field.name;')
+			g.global_initializations.writeln('\t$field.name = ${g.expr_string(field.expr)}; // global')
 		} else {
 			default_initializer := g.type_default(field.typ)
 			if default_initializer == '{0}' {

vlib/v/markused/markused.v

@@ -8,7 +8,7 @@ import v.pref
 
 // mark_used walks the AST, starting at main() and marks all used fns transitively
 pub fn mark_used(mut table ast.Table, pref &pref.Preferences, ast_files []&ast.File) {
-	mut all_fns, all_consts := all_fn_and_const(ast_files)
+	mut all_fns, all_consts, all_globals := all_fn_const_and_global(ast_files)
 	util.timing_start(@METHOD)
 	defer {
 		util.timing_measure(@METHOD)
@@ -316,6 +316,7 @@ pub fn mark_used(mut table ast.Table, pref &pref.Preferences, ast_files []&ast.F
 		files: ast_files
 		all_fns: all_fns
 		all_consts: all_consts
+		all_globals: all_globals
 		pref: pref
 	}
 	// println( all_fns.keys() )
@@ -368,21 +369,24 @@ pub fn mark_used(mut table ast.Table, pref &pref.Preferences, ast_files []&ast.F
 
 	table.used_fns = walker.used_fns.move()
 	table.used_consts = walker.used_consts.move()
+	table.used_globals = walker.used_globals.move()
 
 	$if trace_skip_unused ? {
 		eprintln('>> t.used_fns: $table.used_fns.keys()')
 		eprintln('>> t.used_consts: $table.used_consts.keys()')
+		eprintln('>> t.used_globals: $table.used_globals.keys()')
 		eprintln('>> walker.table.used_maps: $walker.table.used_maps')
 	}
 }
 
-fn all_fn_and_const(ast_files []&ast.File) (map[string]ast.FnDecl, map[string]ast.ConstField) {
+fn all_fn_const_and_global(ast_files []&ast.File) (map[string]ast.FnDecl, map[string]ast.ConstField, map[string]ast.GlobalField) {
 	util.timing_start(@METHOD)
 	defer {
 		util.timing_measure(@METHOD)
 	}
 	mut all_fns := map[string]ast.FnDecl{}
 	mut all_consts := map[string]ast.ConstField{}
+	mut all_globals := map[string]ast.GlobalField{}
 	for i in 0 .. ast_files.len {
 		file := ast_files[i]
 		for node in file.stmts {
@@ -397,9 +401,15 @@ fn all_fn_and_const(ast_files []&ast.File) (map[string]ast.FnDecl, map[string]as
 						all_consts[ckey] = cfield
 					}
 				}
+				ast.GlobalDecl {
+					for gfield in node.fields {
+						gkey := gfield.name
+						all_globals[gkey] = gfield
+					}
+				}
 				else {}
 			}
 		}
 	}
-	return all_fns, all_consts
+	return all_fns, all_consts, all_globals
 }

vlib/v/markused/walker.v

@@ -12,12 +12,14 @@ pub mut:
 	table        &ast.Table
 	used_fns     map[string]bool // used_fns['println'] == true
 	used_consts  map[string]bool // used_consts['os.args'] == true
+	used_globals map[string]bool
 	n_asserts    int
 	pref         &pref.Preferences
 mut:
 	files       []&ast.File
 	all_fns     map[string]ast.FnDecl
 	all_consts  map[string]ast.ConstField
+	all_globals map[string]ast.GlobalField
 }
 
 pub fn (mut w Walker) mark_fn_as_used(fkey string) {
@@ -36,6 +38,15 @@ pub fn (mut w Walker) mark_const_as_used(ckey string) {
 	w.expr(cfield.expr)
 }
 
+pub fn (mut w Walker) mark_global_as_used(ckey string) {
+	$if trace_skip_unused_marked ? {
+		eprintln('  global > |$ckey|')
+	}
+	w.used_globals[ckey] = true
+	gfield := w.all_globals[ckey] or { return }
+	w.expr(gfield.expr)
+}
+
 pub fn (mut w Walker) mark_root_fns(all_fn_root_names []string) {
 	for fn_name in all_fn_root_names {
 		if fn_name !in w.used_fns {
@@ -268,8 +279,11 @@ fn (mut w Walker) expr(node ast.Expr) {
 				.function {
 					w.fn_by_name(node.name)
 				}
+				.global {
+					w.mark_global_as_used(node.name)
+				}
 				else {
-					// `.unresolved`, `.blank_ident`, `.variable`, `.global`, `.function`
+					// `.unresolved`, `.blank_ident`, `.variable`, `.function`
 					// println('>>> else, ast.Ident kind: $node.kind')
 				}
 			}