cgen: pass around functions

vlib/v/checker/checker.v

@@ -1614,8 +1614,10 @@ pub fn (mut c Checker) expr(node ast.Expr) table.Type {
 			return table.string_type
 		}
 		ast.AnonFn {
+			keep_ret_type := c.fn_return_type
 			c.fn_return_type = it.decl.return_type
 			c.stmts(it.decl.stmts)
+			c.fn_return_type = keep_ret_type
 			return it.typ
 		}
 		else {

vlib/v/gen/cgen.v

@@ -358,7 +358,10 @@ typedef struct {
 			.function {
 				info := typ.info as table.FnType
 				func := info.func
-				if !info.has_decl && !info.is_anon {
+				sym := g.table.get_type_symbol(func.return_type)
+				is_multi :=  sym.kind == .multi_return
+				is_fn_sig := func.name == ''
+				if !info.has_decl && (!info.is_anon || is_fn_sig) && !is_multi {
 					fn_name := if func.is_c {
 						func.name.replace('.', '__')
 					} else if info.is_anon {
@@ -556,6 +559,7 @@ fn (mut g Gen) stmt(node ast.Stmt) {
 					println('build module `$g.module_built` fn `$it.name`')
 				}
 			}
+			keep_fn_decl := g.fn_decl
 			g.fn_decl = it // &it
 			if it.name == 'main' {
 				// just remember `it`; main code will be generated in finish()
@@ -563,7 +567,7 @@ fn (mut g Gen) stmt(node ast.Stmt) {
 			} else {
 				g.gen_fn_decl(it)
 			}
-			g.fn_decl = 0
+			g.fn_decl = keep_fn_decl
 			if skip {
 				g.out.go_back_to(pos)
 			}
@@ -820,15 +824,22 @@ fn (mut g Gen) gen_assign_stmt(assign_stmt ast.AssignStmt) {
 	if assign_stmt.is_static {
 		g.write('static ')
 	}
-	if assign_stmt.left.len > assign_stmt.right.len {
+	mut return_type := table.void_type
+	if assign_stmt.right[0] is ast.CallExpr {
+		it := assign_stmt.right[0] as ast.CallExpr
+		return_type = it.return_type
+	}
+	mut is_multi := false
+	// json_test failed w/o this check
+	if return_type != 0 {
+		sym := g.table.get_type_symbol(return_type)
+		// the left vs. right is ugly and should be removed
+		is_multi = sym.kind == .multi_return || assign_stmt.left.len > assign_stmt.right.len || 
+			assign_stmt.left.len > 1
+	}
+	if is_multi {
 		// multi return
 		mut or_stmts := []ast.Stmt{}
-		mut return_type := table.void_type
-		if assign_stmt.right[0] is ast.CallExpr {
-			it := assign_stmt.right[0] as ast.CallExpr
-			or_stmts = it.or_block.stmts
-			return_type = it.return_type
-		}
 		is_optional := return_type.flag_is(.optional)
 		mr_var_name := 'mr_$assign_stmt.pos.pos'
 		mr_styp := g.typ(return_type)
@@ -865,7 +876,7 @@ fn (mut g Gen) gen_assign_stmt(assign_stmt ast.AssignStmt) {
 			styp := g.typ(ident_var_info.typ)
 			mut is_call := false
 			mut or_stmts := []ast.Stmt{}
-			mut return_type := table.void_type
+			blank_assign := ident.kind == .blank_ident
 			match val {
 				ast.CallExpr {
 					is_call = true
@@ -874,6 +885,9 @@ fn (mut g Gen) gen_assign_stmt(assign_stmt ast.AssignStmt) {
 				}
 				ast.AnonFn {
 					// TODO: no buffer fiddling
+					if blank_assign {
+						g.write('{')
+					}
 					ret_styp := g.typ(it.decl.return_type)
 					g.write('$ret_styp (*$ident.name) (')
 					def_pos := g.definitions.len
@@ -882,13 +896,16 @@ fn (mut g Gen) gen_assign_stmt(assign_stmt ast.AssignStmt) {
 					g.write(') = ')
 					g.expr(*it)
 					g.writeln(';')
+					if blank_assign {
+						g.write('}')
+					}
 					continue
 				}
 				else {}
 			}
 			gen_or := is_call && return_type.flag_is(.optional)
 			g.is_assign_rhs = true
-			if ident.kind == .blank_ident {
+			if blank_assign {
 				if is_call {
 					g.expr(val)
 				} else {
@@ -1909,8 +1926,13 @@ fn (mut g Gen) return_statement(node ast.Return) {
 		return
 	}
 	fn_return_is_optional := g.fn_decl.return_type.flag_is(.optional)
-	// multiple returns
+
-	if node.exprs.len > 1 {
+	// got to do a correct check for multireturn
+	sym := g.table.get_type_symbol(g.fn_decl.return_type)
+	fn_return_is_multi := sym.kind == .multi_return
+
+	// optional multi not supported
+	if fn_return_is_multi && !fn_return_is_optional {
 		g.write(' ')
 		// typ_sym := g.table.get_type_symbol(g.fn_decl.return_type)
 		// mr_info := typ_sym.info as table.MultiReturn
@@ -1933,7 +1955,7 @@ fn (mut g Gen) return_statement(node ast.Return) {
 		if fn_return_is_optional {
 			g.write(' }, sizeof($styp))')
 		}
-	} else if node.exprs.len == 1 {
+	} else if node.exprs.len >= 1 {
 		// normal return
 		g.write(' ')
 		return_sym := g.table.get_type_symbol(node.types[0])

vlib/v/table/table.v

@@ -369,11 +369,12 @@ pub fn (mut t Table) find_or_register_multi_return(mr_typs []Type) int {
 
 pub fn (mut t Table) find_or_register_fn_type(f Fn, is_anon, has_decl bool) int {
 	name := if f.name.len == 0 { 'anon_fn_$f.signature()' } else { f.name }
+	anon := f.name.len == 0 || is_anon
 	return t.register_type_symbol(TypeSymbol{
 		kind: .function
 		name: name
 		info: FnType{
-			is_anon: f.name.len == 0 || is_anon
+			is_anon: anon
 			has_decl: has_decl
 			func: f
 		}

vlib/v/tests/fn_test.v

@@ -120,6 +120,58 @@ fn high_fn_multi_return(a int, b fn (c []int, d []string) ([]int, []string)) {
 
 }
 
+fn high_fn_return_single_anon() (fn(int)f32) {
+	_ := 1
+	correct := fn(n int)f32 {
+		return n * n
+	}
+	return correct
+}
+fn high_fn_return_multi_anons() (fn(int)f32, fn(int)string) {
+	// parsing trap
+	_ := fn(n int)byte {
+		return 0x00
+	}
+	correct_second := fn(n int)string {
+		return '$n'
+	}
+	correct_first := fn(n int)f32 {
+		return n * n
+	}
+	// parsing trap
+	_ := fn(n int)[]int {
+		return [n]
+	}
+	return correct_first, correct_second
+}
+fn high_fn_return_named_fn() (fn(int)int) {
+	return sqr
+}
+fn test_high_fn_ret_anons() {
+	param := 13
+	func_sqr1 := high_fn_return_single_anon()
+	assert func_sqr1(param) == param * param
+
+	func_sqr2, func_repr := high_fn_return_multi_anons()
+	assert func_sqr2(param) == (param * param)
+	assert func_repr(param) == '$param'
+
+	top_lvl_sqr := high_fn_return_named_fn()
+	assert top_lvl_sqr(param) == param * param
+}
+
+fn high_fn_applier(arg int, func fn(a int)string) string {
+	return func(arg)
+}
+fn test_high_fn_applier() {
+	arg := 13
+	expect := '$arg $arg'
+	func := fn (arg int) string {
+		return '$arg $arg'
+	}
+	assert expect == high_fn_applier(arg, func)
+}
+
 fn sqr(x int) int {
 	return x * x
 }