build example error on gcc 4.8 .

[aengusjiang]

in file: bin_to_hex.h

#if defined(__has_include) && __has_include()

include

#endif

error: missing binary operator before token "("
#if defined(__has_include) && __has_include()

[gabime]

Thanks. which compiler version?

[aengusjiang]

gcc (GCC) 4.8.5 20150623 (Red Hat 4.8.5-44)
Copyright (C) 2015 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

and the spdlog version:1.10

[aengusjiang]

step:
cmake -B build .
cd build
make

then the error as below:

[gabime]

I dont have gcc 4.8 to reproduce. Please open a pr with a fix.

[aengusjiang]

open a pr? What's mean? What can to do for you?

[gabime]

Create a pull request with the fix.

[aengusjiang]

According to the gcc support doc, the __has_include macro support required gcc 5.0 and up. 发自我的手机

…

-------- 原始邮件 -------- 发件人： ***@***.*** 日期： 2022年4月9日周六 19:49 收件人： gabime/spdlog ***@***.***> 主 题： 回复：[gabime/spdlog] build example error on gcc 4.8 . (Issue #2333) open a pr? What's mean? What can to do for you?

[gabime]

so maybe surround with ifdef?

[aengusjiang]

it works on gcc version 8.3.1 20191121,
but I try to surrond with ifdef like below：
--- a/include/spdlog/fmt/bin_to_hex.h
+++ b/include/spdlog/fmt/bin_to_hex.h
@@ -8,9 +8,13 @@
#include
#include <spdlog/common.h>

+// __has_include feature require c++17 standard
+// see https://gcc.gnu.org/projects/cxx-status.html
+#if 201703L <= __cplusplus
#if defined(__has_include) && __has_include()

include

#endif
+#endif
then， it still has error：

I think that the user_defined_example requre the higher gcc version to support the template specialization.
That is say it don't support with low version such gcc4.8.5.

[kslattery]

@gabime Should be able to close this issue and #2354.

[stephen-derosa]

what was the solution here for building on gcc < 9? Just to upgrade gcc?