Xcode build time frustration

I have the same issue, but since Xcode 16 my build time has increased by A LOT

We have changed our configuration to:

• Debug: ENABLE_MODULE_VERIFIER = NO
• Release: ENABLE_MODULE_VERIFIER = YES

Great relief!

Of course with a risk that module verifier first fails when we build a release build.

The module verifier is not expected to run for every incremental build. However, if there is a Run Script build phase with no specified output files that runs on every incremental build, the module verifier will defensively run in case the script modifies any module contents (headers or module maps).

Specifying the input and output files for each Run Script build phase will allow the phase to be skipped in incremental builds when it isn't needed, and thus allow the module verifier to be skipped. https://developer.apple.com/documentation/xcode/running-custom-scripts-during-a-build#Specify-the-input-and-output-files-for-your-script has some details about this.

Where it isn't easy to specify any input or output files, a workaround is to specify a "dummy" output file so that Xcode can know that the Run Script phase doesn't affect the module. Add an output file that is $(DERIVED_FILE_DIR)/NameOfScriptPhase.txt, and at the end of the script add a touch "$DERIVED_FILE_DIR/NameOfScriptPhase.txt". Note that this is not recommended, fully specifying the real input and output files is how to best allow the Xcode build system to schedule and run your Run Script build phase.

Apple is following an issue where building clang modules in C++ language modes is slow. As a temporary workaround, you can also remove c++ and objective-c++ from the MODULE_VERIFIER_SUPPORTED_LANGUAGES build setting in the Debug configuration if the above steps don't help the issue. ENABLE_MODULE_VERIFIER can also be disabled, but that should be the last resort.

I'm seeing this issue despite removing all custom build scripts

Removing "objective-c++" from MODULE_VERIFIER_SUPPORTED_LANGUAGES in each framework made it much faster (44s -> 14s)

But it looks like the verification is still happening each time, it's just faster. I disabled it for the frameworks and gained another 0.5s of build time back.

In my case, it was about properly disabling explicit modules which required setting CLANG_ENABLE_EXPLICIT_MODULES to NO. This would revert a significantly slow step of scanning dependencies from every file.

After upgrading to Xcode 16, I have experienced some issues with the compilation time of my project.

I noticed that a new step has been added called "Scan dependencies of", which was not present in Xcode 15.

Additionally, there is a new CompileAssetCatalogVariant step. The ValidateEmbeddedBinary step has started to take ~15 seconds, compared to about 5 seconds in Xcode 15.

I would appreciate any recommendations on what I can do with that information 🙏