CODEWITHSUNDEEP
cgcccmake
Martel
Martel

Reputation: 2744

GCC warnings not detected in cmake debug builds, but detected in release ones

I have a cmake/gcc project in which I have enabled several warnings and the flag -Werror.

I have noticed that some warnings are detected when I use the cmake flag -DCMAKE_BUILD_TYPE=Release, but they are not when I don't apply the above cmake flag. For example, one of these warnings is:

error: ‘var_name’ may be used uninitialized in this function [-Werror=maybe-uninitialized]

I have read here: Set CFLAGS and CXXFLAGS options using CMake that there are several CMAKE_C_FLAGS variables for different build types, for instance, CMAKE_C_FLAGS_RELEASE.

I have tried to apply those variables for release and debug builds, but this time none of the above detect the warnings I'm expecting.

What I'm missing?

Upvotes: 1

Views: 518

Answers (1)

R.. GitHub STOP HELPING ICE
R.. GitHub STOP HELPING ICE

Reputation: 215617

CMake's default/"debug" build profile entirely disables optimization, which prevents the compiler passes that perform transformations and static analysis needed to determine that a variable is used uninitialized from ever happening. While to some extent this improves debugging experience with single-step of source lines, as you've found it hides warnings and also tends to hide consequences of undefined behavior in your code.

Traditionally "disable optimizations entirely for non-release builds" has not been a thing among unix-oriented developers. It's a carry-over from common practice in the MSVC world that's reflective of CMake's origins and user base.

Upvotes: 2

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