Symbol graphs missing for C (C++/Obj-C) targets with swiftbuild build system

[cmcgee1024]

Is it reproducible with SwiftPM command-line tools: swift build, swift test, swift package etc?

• Confirmed reproduction steps with SwiftPM CLI. The description text must include reproduction steps with either of command-line SwiftPM commands, swift build, swift test, swift package etc.

Description

Swift build is not currently emitting symbol graphs upon request for C targets using clang.

Steps to reproduce:

• Create a SwiftPM package with a simple C target
• Run swift package --build-system swiftbuild dump-symbol-graph

Expected result:
The symbol graph for the C target can be found in the symbol graph directory (e.g. .build/arm64-apple-macosx/symbolgraph/CTarget.symbols.json) just as it does for the native build system.

Actual result:
Swift targets output their symbol graphs there, but not the C targets.

Expected behavior

No response

Actual behavior

No response

Steps to reproduce

No response

Swift Package Manager version/commit hash

No response

Swift & OS version (output of swift --version ; uname -a)

No response

[cmcgee1024]

SwiftPM is adding the RUN_SYMBOL_GRAPH_EXTRACT build setting, but for C targets this is being ignored entirely. Instead, there should be support added for Clang to emit the graph.