fix(ios): force fmt 12.1.0 in the example so it compiles on Xcode 26.4+ - #349
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RN 0.80's bundled fmt 11.0.2 fails to build on Xcode 26.4+ (Apple clang 21 rejects fmt's consteval FMT_STRING path, expo/expo#44229). The previous FMT_USE_CONSTEVAL=0 build setting never took effect: fmt 11.0.2 predates the escape hatch (fmt 11.1) and unconditionally re-defines the macro. Instead of patching fmt sources, force fmt 12.1.0 — the version RN 0.86 ships, where the consteval code is actually fixed — by rewriting the vendored fmt/RCT-Folly podspecs before dependency resolution (RCT-Folly exact-pins fmt). Verified on Xcode 26.5: full example build succeeds and the iOS harness suite passes (26 suites / 204 tests). Drop once the example is on RN >= 0.83.
This was referenced Jul 17, 2026
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RN 0.80's bundled fmt 11.0.2 fails to compile on Xcode 26.4+ (Apple clang 21 rejects fmt's consteval
FMT_STRINGpath, expo/expo#44229). TheFMT_USE_CONSTEVAL=0build setting the Podfile used never took effect: fmt 11.0.2 predates the#ifdefescape hatch (added in fmt 11.1) and unconditionally re-defines the macro.Instead of patching fmt sources, force fmt 12.1.0 — the version RN 0.86 ships, where the consteval code is fixed upstream — by rewriting the vendored
fmt.podspecandRCT-Folly.podspec(which exact-pins fmt) before dependency resolution, and dropping stalePods/Local PodspecsJSONs that CocoaPods would otherwise reuse. First install after this change needspod update fmtorrm Podfile.lock(CI already deletes the lock). Drop the whole block once the example is on RN >= 0.83.Verified on Xcode 26.5: full example build succeeds and the iOS harness suite passes (26 suites / 204 tests).