fix(learn): 解决 linux 上编译错误

Signed-off-by: YdrMaster <[email protected]>

Author: YdrMaster

learn/test.cpp

@@ -36,9 +36,10 @@ static bool test_exercise(std::ostream &os, int n, const char *log) {
 
 bool test_exercise(int n, const char *log) {
     if (log) {
-        auto log_ = fs::absolute(fs::path(XMAKE) / "log" / log);
-        auto log__ = log_.string();
-        return test_exercise(std::fstream(log_, std::ios::out | std::ios::app), n, log__.c_str());
+        const auto log_ = fs::absolute(fs::path(XMAKE) / "log" / log);
+        const auto log__ = log_.string();
+        auto file = std::fstream(log_, std::ios::out | std::ios::app);
+        return test_exercise(file, n, log__.c_str());
     } else {
         return test_exercise(std::cout, n, nullptr);
     }

xmake.lua

@@ -1,20 +1,19 @@
 add_rules("mode.debug", "mode.release")
 set_encodings("utf-8")
+set_warnings("all")
+set_languages("cxx17")
 
 target("test")
     set_kind("static")
-    set_languages("cxx17")
     add_defines(string.format("__XMAKE__=\"%s\"", os.scriptdir():gsub("\\", "/")))
     add_files("learn/test.cpp")
 
 target("learn")
     set_kind("binary")
-    set_languages("cxx17")
     add_deps("test")
     add_files("learn/learn.cpp")
 
 target("summary")
     set_kind("binary")
-    set_languages("cxx17")
     add_deps("test")
     add_files("learn/summary.cpp")