C++ no 'object' file generated

Question

This is some code to get an environment variable from inside Qt, however, it seems Qt's QProcessEnvironment::systemEnvironment() only reflect a new environment variable change after reboot. So I am thinking about using getenv. However I got "error C2220: warning treated as error - no 'object' file generated" from this :

QProcessEnvironment env = QProcessEnvironment::systemEnvironment();
const QString ENGINE_ROOT = env.value("ENGINE_ROOT", "") != "" ? 
env.value("ENGINE_ROOT","") : QString(getenv("ENGINE_ROOT"));

Don't tell me something like disable /WX or lower W4 to W3, I don't want to hear this, I want to know exactly what cause

no 'object' file generated

.

Answer 1

"error C2220: warning treated as error - no 'object' file generated"

The error already answers your question:

1. A warning was generated.
2. Because you have told the compiler to treat warnings as errors, an error occurred.
3. Because an error occurred, the compiler did not generate an object file.

If you want to know what the original warning means, then you need to ask us about that warning.

Answer 2

I'll address the underlying question instead of the compilation problem.

Environment variables for any process are copied from those of its parent process when your new process is started. From that point, the only thing that can modify them is your process yourself.

In practical terms, this means that going to the Windows dialog box to change environment variables does not change those values for any existing processes. Those changes are applied to the explorer.exe process, and then any new processes launched from Explorer.

There is a possible way for a Windows application to get notified of changes made to environment variables made by Explorer. See How to modify the PATH variable definitely through the command line in Windows for details.

Answer 3

in my case, eliminating all useless 'object' will deal this erro

Answer 4

I just had this problem. The real source of the confusion is that Microsoft Visual Studio lists the
error C2220: warning treated as error - no 'object' file generated
line separately from the warnings--sometimes even before the warnings--so it is not immediately apparent that the error is related to the listed warnings.

Fix all warnings listed to fix this problem.