cgen: fix match tmp var needing check when working with option on branches (#17837)

vlib/v/gen/c/if.v

@@ -37,6 +37,16 @@ fn (mut g Gen) need_tmp_var_in_expr(expr ast.Expr) bool {
 		return true
 	}
 	match expr {
+		ast.Ident {
+			return expr.or_expr.kind != .absent
+		}
+		ast.StringInterLiteral {
+			for e in expr.exprs {
+				if g.need_tmp_var_in_expr(e) {
+					return true
+				}
+			}
+		}
 		ast.IfExpr {
 			if g.need_tmp_var_in_if(expr) {
 				return true
@@ -134,7 +144,10 @@ fn (mut g Gen) need_tmp_var_in_expr(expr ast.Expr) bool {
 			}
 		}
 		ast.SelectorExpr {
-			return g.need_tmp_var_in_expr(expr.expr)
+			if g.need_tmp_var_in_expr(expr.expr) {
+				return true
+			}
+			return expr.or_block.kind != .absent
 		}
 		else {}
 	}

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)} ${cond_var} = ')
+		g.write('${g.typ(node.cond_type)} /*A*/ ${cond_var} = ')
 		g.expr(node.cond)
 		g.writeln(';')
 		g.set_current_pos_as_last_stmt_pos()

vlib/v/tests/option_match_expr_test.v

@@ -0,0 +1,30 @@
+pub struct ParamPrecos {
+pub:
+	code      string [required]
+	table_ref ?i64
+}
+
+fn test_none() {
+	pp := ParamPrecos{
+		code: 'V'
+	}
+
+	tx_ref := match pp.table_ref {
+		none { 'num: none' }
+		else { 'num: ${pp.table_ref?}' }
+	}
+	assert tx_ref == 'num: none'
+}
+
+fn test_not_none() {
+	pp := ParamPrecos{
+		code: 'V'
+		table_ref: 123
+	}
+
+	tx_ref := match pp.table_ref {
+		none { 'num: none' }
+		else { 'num: ${pp.table_ref?}' }
+	}
+	assert tx_ref == 'num: 123'
+}