add test workflow

[yaito3014]

No description provided.

[github-actions]

The latest workflow run for this pull request is #3

[github-actions]

The latest workflow run for this pull request is #4

[github-actions]

The latest workflow run for this pull request is #5

[github-actions]

The latest workflow run for this pull request is #15, and the compilation output is:

[github-actions]

The latest workflow run for this pull request is #16, and the compilation output is:

[github-actions]

compilation output is:

source.cpp: In function ‘int main()’:
source.cpp:7:7: warning: ignoring return value of ‘int func()’, declared with attribute ‘nodiscard’ [-Wunused-result]
    7 |   func();
      |   ~~~~^~
source.cpp:3:19: note: declared here
    3 | [[nodiscard]] int func() { return 42; }
      |                   ^~~~
source.cpp:6:7: warning: unused variable ‘unused_variable’ [-Wunused-variable]
    6 |   int unused_variable = 42;
      |       ^~~~~~~~~~~~~~~

[github-actions]

compilation output is:

source.cpp: In function ‘int main()’:
source.cpp:7:7: warning: ignoring return value of ‘int func()’, declared with attribute ‘nodiscard’ [-Wunused-result]
    7 |   func();
      |   ~~~~^~
source.cpp:3:19: note: declared here
    3 | [[nodiscard]] int func() { return 42; }
      |                   ^~~~
source.cpp:6:7: warning: unused variable ‘unused_variable’ [-Wunused-variable]
    6 |   int unused_variable = 42;
      |       ^~~~~~~~~~~~~~~