Fix Bazel hot-reload: handle .swift-suffixed include paths and stale -o flags

[maatheusgois-dd]

Summary

Fixes three issues that prevent hot-reload injection from working in Bazel monorepos (particularly with rules_xcodeproj):

1. .swift-suffixed include paths misclassified as source files

FrontendServer.swift — CompilationArgParser.process

SPM packages with names ending in .swift (e.g. ulid.swift) produce include paths like -I/path/to/swiftpkg_ulid.swift. The arg parser checks hasSuffix(".swift") and only excluded -F as a predecessor flag. This caused the path to be added to swiftFiles instead of args, breaking compilation.

Fix: Expanded the guard to check for -I, -iquote, -isystem in addition to -F. Also handles the concatenated form (-I/path/...) where the flag and path are a single token, by checking hasPrefix("-I") and hasPrefix("-F").

2. Stale -o flag from original build causes object file to be written to wrong path

NextCompiler.swift — recompile

The stored compilation arguments contain the original -o /path/to/bazel/output.o from the Bazel build. NextCompiler appends its own -o eval1.o, but swift-frontend uses the first -o it encounters, so the .o file is written to the Bazel path instead of the expected temp path. The linker then fails with no such file or directory: eval1.o.

Fix: Filter out any existing -o <value> pair from stored.arguments before appending the new output path. Uses a skipNext flag to consume the value token after -o.

Also re-adds WMO flag filtering (-whole-module-optimization, -internalize-at-link, -no-serialize-debugging-options) that was removed in the Xcode26.3 branch — these flags prevent single-file recompilation.

3. Restored local tmpbase for NextCompiler

The Xcode26.3 branch switched NextCompiler to use Reloader.tmpbase (which resolves to NSTemporaryDirectory() + "eval\(N)"), but the link() method in NextCompiler expects the object at /tmp/injectionNext_N.o. Restored the local let tmpbase = "/tmp/injectionNext" to keep the two paths consistent.

4. Updated BAZEL.md documentation

Replaced the "rules_xcodeproj Limitation" warning (which stated hot-reload doesn't work with rules_xcodeproj) with documentation explaining how InjectionNext now handles rules_xcodeproj output bases.

Impact on other Bazel implementations

These changes are backwards-compatible and should not break existing Bazel workflows:

• The -I/-F prefix check in FrontendServer is strictly additive — it only prevents misclassification of paths that were previously incorrectly treated as source files. Standard .swift source files are unaffected since they don't start with -I or -F.
• The -o stripping in NextCompiler only affects the stored args before the injection-specific -o is appended. The original build is never modified.
• WMO flag filtering was already present on the main branch — this just restores it to Xcode26.3.
• The tmpbase change only affects NextCompiler's internal temp file paths and doesn't touch any Bazel build artifacts.

Testing

Tested on Bazel project with rules_xcodeproj:

• Compilation args correctly exclude ulid.swift include paths from source file list
• Object file written to correct temp path
• Linking proceeds with correct .o path

Related Pull Request: johnno1962/InjectionLite#23
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