CI is broken on current GitHub runner images and JUCE develop

[drowaudio]

Both CI workflows have been red since the runner images moved on. Master last went fully green on 2025-08-22 (Merge pull request #263); every run since fails before reaching the test stage on most platforms. Noticed while working on #405, where 17 of 36 checks fail for reasons unrelated to the branch.

There are two independent groups.

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1. Build workflow (.github/workflows/build.yaml) - pinned JUCE 8.0.6 vs current runner images

These are toolchain/SDK problems, not JUCE API drift. The JUCE submodule is pinned at 19edd53 (8.0.6, Feb 2025).

a. _LIBCPP_ENABLE_ASSERTIONS was removed from libc++

/Applications/Xcode_26.6.app/.../MacOSX26.5.sdk/usr/include/c++/v1/__configuration/hardening.h:25:4:
error: "_LIBCPP_ENABLE_ASSERTIONS has been removed, please use _LIBCPP_HARDENING_MODE=<mode> instead (see docs)"

JUCE's juce_recommended_config_flags still defines _LIBCPP_ENABLE_ASSERTIONS=1 in Debug on Apple. Fails: test (Debug, macOS, TestRunner), test (Debug, macOS, Benchmarks). Also reproduces locally on macOS 26.5; the local workaround is configuring with -DCMAKE_CXX_FLAGS_DEBUG="-g -U_LIBCPP_ENABLE_ASSERTIONS", but the real fix is a JUCE bump (JUCE now sets _LIBCPP_HARDENING_MODE) or dropping the flag in our CMake.

b. -Werror on pre-existing implicit conversions (Release only)

15 unique -Wimplicit-int-float-conversion errors, all in our own headers:

• modules/tracktion_core/utilities/tracktion_Time.h:470:39 - long long to double
• modules/tracktion_graph/utilities/tracktion_PerformanceMeasurement.h:303:28 and 305:31 - uint64_t to double
• modules/tracktion_engine/plugins/external/tracktion_VSTXML.h:199:37, 200:47 - int to float
• modules/tracktion_engine/utilities/tracktion_BackgroundJobs.h:200:48 - int to float
• modules/tracktion_engine/utilities/tracktion_Ditherer.h:24:28 - int to float, "changes value from 2147483647 to 2147483648"

Newer clang promoted these from warnings to diagnostics we now trip over, and examples/TestRunner/CMakeLists.txt compiles Release with -Werror. Fails: all test (Release, macOS, *), macOS_analyse, macOS_asan. The Ditherer.h one looks worth a genuine look rather than a blanket cast - it is an actual value change.

c. MSVC C4458 in JUCE promoted to an error

modules\juce\...\format_types\juce_VST3PluginFormat.cpp(744,55): warning C4458: declaration of `iid` hides class member
...(780,51): same
error C2220: the following warning is treated as an error

Fails: all test (Release, windows, *). Needs a JUCE bump or /wd4458 for the JUCE sources.

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2. juce_compatability workflow (.github/workflows/juce_compat.yaml) - real API drift against JUCE develop

This workflow builds with -DJUCE_CPM_DEVELOP=1, so it pulls JUCE develop tip. It is doing its job: these are genuine incompatibilities to fix in our code.

a. Stale Xcode pin - infrastructure

xcode-select: error: invalid developer directory `/Applications/Xcode_15.3.app`

juce_compat.yaml:39 pins Xcode_15.3.app, which no longer exists on macos-26-arm64. build (macOS) dies after 5 seconds. Either drop the pin or move it to a version the image actually ships.

b. AudioFormat::createWriterFor signature changed

modules/tracktion_engine/audio_files/formats/tracktion_FloatAudioFileFormat.h:40:30:
error: `FloatAudioFormat::createWriterFor(...)` marked `override`, but does not override

Knock-on: FloatAudioFormat becomes abstract, so tracktion_AudioFormatManager.cpp:64 and :84 fail with cannot instantiate abstract class.

c. juce::DrawableRectangle is no longer a Component

In examples/common/Utilities.h:

• :314, :317, :320 - no matching addAndMakeVisible / addChildComponent for juce::DrawableRectangle&
• :446, :447, :459, :466 - DrawableRectangle has no member setVisible

d. JUCE_USE_CURL / JUCE_WEB_BROWSER redefined [-Werror]

<command-line>: error: "JUCE_USE_CURL" redefined
<command-line>: error: "JUCE_WEB_BROWSER" redefined

The examples set these both via target_compile_definitions and via the JUCE module config, and gcc treats the redefinition as an error.

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Suggested order

1. Fix the Xcode pin in juce_compat.yaml (one line, unblocks build (macOS) reaching a real result).
2. Bump the JUCE submodule - likely clears (1a) and (1c) together.
3. Fix the -Werror conversions in our headers, giving Ditherer.h:24 a proper look.
4. Fix the JUCE develop API drift in FloatAudioFileFormat.h and examples/common/Utilities.h.

Happy to pick any of these up.

[drowaudio]

🤖 Opened #408 for this issue.

[drowaudio]

Yes, do all of those in that order

[drowaudio]

Closing - this was a master-vs-develop artefact, not a real CI problem. #405 was accidentally opened against master, which has not moved since August 2025. develop already has the runner-image, JUCE-submodule and -Werror fixes and is fully green on both the Build and juce_compatability workflows (latest run on b88a6ee). #405 is being rebased onto develop.