cgen: fix generated code for handling fn call with result/option return on match conditional (#21608)

vlib/v/gen/c/match.v

@@ -81,7 +81,7 @@ fn (mut g Gen) match_expr(node ast.MatchExpr) {
 			''
 		}
 		cond_var = g.new_tmp_var()
-		g.write('${g.typ(node.cond_type)} /*A*/ ${cond_var} = ')
+		g.write('${g.typ(node.cond_type)} ${cond_var} = ')
 		g.expr(node.cond)
 		g.writeln(';')
 		g.set_current_pos_as_last_stmt_pos()
@@ -419,6 +419,8 @@ fn (mut g Gen) match_expr_classic(node ast.MatchExpr, is_expr bool, cond_var str
 	node_cond_type_unsigned := node.cond_type in [ast.u16_type, ast.u32_type, ast.u64_type]
 	type_sym := g.table.final_sym(node.cond_type)
 	use_ternary := is_expr && tmp_var == ''
+	mut reset_if := false
+	mut has_goto := false
 	for j, branch in node.branches {
 		is_last := j == node.branches.len - 1
 		if branch.is_else || (use_ternary && is_last) {
@@ -439,7 +441,11 @@ fn (mut g Gen) match_expr_classic(node ast.MatchExpr, is_expr bool, cond_var str
 				} else {
 					g.writeln('')
 					g.write_v_source_line_info(branch)
-					g.write('else ')
+					if !reset_if {
+						g.write('else ')
+					} else {
+						reset_if = false
+					}
 				}
 			}
 			if use_ternary {
@@ -451,6 +457,7 @@ fn (mut g Gen) match_expr_classic(node ast.MatchExpr, is_expr bool, cond_var str
 				g.write_v_source_line_info(branch)
 				g.write('if (')
 			}
+			reset_if = branch.exprs.any(g.match_must_reset_if(it))
 			for i, expr in branch.exprs {
 				if i > 0 {
 					g.write(' || ')
@@ -532,7 +539,33 @@ fn (mut g Gen) match_expr_classic(node ast.MatchExpr, is_expr bool, cond_var str
 		g.stmts_with_tmp_var(branch.stmts, tmp_var)
 		g.expected_cast_type = 0
 		if g.inside_ternary == 0 && node.branches.len >= 1 {
-			g.write('}')
+			if reset_if {
+				has_goto = true
+				g.writeln('\tgoto end_block_${node.pos.line_nr};')
+				g.writeln('}')
+				g.set_current_pos_as_last_stmt_pos()
+			} else {
+				g.write('}')
+			}
+		}
+	}
+	if has_goto {
+		g.writeln('end_block_${node.pos.line_nr}: {}')
+		g.set_current_pos_as_last_stmt_pos()
+	}
+}
+
+// match_must_reset_if checks if codegen must break the if-elseif sequence in another if expr
+fn (mut g Gen) match_must_reset_if(node ast.Expr) bool {
+	return match node {
+		ast.CallExpr {
+			node.or_block.kind != .absent
+		}
+		ast.InfixExpr {
+			g.match_must_reset_if(node.left) || g.match_must_reset_if(node.right)
+		}
+		else {
+			false
 		}
 	}
 }

vlib/v/tests/match_expr_result_test.v

@@ -0,0 +1,23 @@
+fn try(this string) !bool {
+	return true
+}
+
+fn test_case1() {
+	a, b := match true {
+		try('foo')! { 'a', 'b' }
+		try('bar')! { 'c', 'd' }
+		else { 'e', 'f' }
+	}
+	assert a == 'a'
+	assert b == 'b'
+}
+
+fn test_case2() {
+	a, b := match true {
+		try('foo')! && try('foo') or { false } { 'a', 'b' }
+		try('bar') or { false } { 'c', 'd' }
+		else { 'e', 'f' }
+	}
+	assert a == 'a'
+	assert b == 'b'
+}