Swift Compiler 5.8 / Xcode 14.3 RC -strict-implicit-module-context not pass to swift-frontend

[Fushj89]

Description
Use Xcode 14.3 RC , set -strict-implicit-module-context flag on Other Swift Flags of Building Settings, when compile swift file, the -strict-implicit-module-context flag only appear swiftc command, does not appear swift-frontend command

Steps to reproduce
1、Use Xcode 14.3 RC , set -strict-implicit-module-context flag on Other Swift Flags of Building Settings
2、Build swift file
3、See swiftc command and swift-frontend command by XCode build message log

Expected behavior
-strict-implicit-module-context flag pass to swift-frontend

Environment

• Swift compiler version info swift-driver version: 1.75.2 Apple Swift version 5.8 (swiftlang-5.8.0.124.1 clang-1403.0.22.11.100)
• Xcode version info Xcode 14.3 Build version 14E222a

[Fushj89]

the -strict-implicit-module-context flag does not appear in the result of swiftc --help command

[tshortli]

When the frontend has a flag but the driver doesn't have an equivalent flag, you can pass the flag directly to the frontend by adding -Xfrontend before it in the driver flags, e.g. OTHER_SWIFT_FLAGS = $(inherited) -Xfrontend -strict-implicit-module-context.

[Fushj89]

@tshortli thank you very much, it solves my problem. I try to find -Xfrontend from the result of swiftc --help, but it does not appear. It should be better if -Xfrontend appear in the result of swiftc --help

[tshortli]

@Fushj89 -Xfrontend is not documented because strictly speaking it's not meant for general use. The -strict-implicit-module-context also isn't yet an official, supported flag. You're of course free to use them to work around the issue you're encountering, but they are not generally advertised because there is not yet a formal commitment to supporting them. You can read a bit more about the topic of private Swift compiler flags here: https://forums.swift.org/t/is-xfrontend-forbidding-enough/18791/5