c:\Temp>gcc -Wall test_vscode.c
test_vscode.c: In function 'main':
test_vscode.c:3:11: warning: left-hand operand of comma expression has no effect [-Wunused-value]
     a = (3,4);
           ^

c:\Temp>gcc -Wall test_vscode.c
test_vscode.c: In function 'main':
test_vscode.c:3:10: warning: right-hand operand of comma expression has no effect [-Wunused-value]
     a = 3,4;
          ^