fix(xlswriter): fix macOS build with modern Clang (C23)

[dunglas]

Summary

• The bundled minizip in xlswriter (pinned at libxlsxwriter RELEASE_1.0.0) uses a K&R-style function declaration in mztools.c
• Modern Clang on macOS defaults to C23, which removed K&R function definitions from the standard — this causes a hard syntax error, not a suppressible warning
• The upstream libxlsxwriter main branch already has the ANSI C fix; the PECL extension just pins an old release
• This patch converts the K&R declaration to ANSI C in patchBeforeMake(), matching the upstream fix

Error

ext/xlswriter/library/libxlsxwriter/third_party/minizip/mztools.c:30:30: error: unknown type name 'file'
   30 | extern int ZEXPORT unzRepair(file, fileOut, fileOutTmp, nRecovered, bytesRecovered)

Test plan

• Verify the fix applies cleanly by checking the string replacement targets match the actual source from PECL xlswriter
• macOS build should succeed with this patch

🤖 Generated with Claude Code

[Copilot]

Pull request overview

Updates the xlswriter extension build patching step to fix a macOS build failure with modern Clang/C23 by converting a K&R-style unzRepair declaration in bundled minizip to an ANSI C prototype.

Changes:

• Add a patchBeforeMake() replacement targeting libxlsxwriter/third_party/minizip/mztools.c to rewrite the K&R-style unzRepair signature into an ANSI C declaration.
• Import and use SPC\store\FileSystem to perform the in-file string replacement.

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[henderkes]

It sounds like it makes sense, but I'm building on Linux in C23 mode with Clang, too. I would like to understand why it only fails on mac.

[dunglas]

It's an Apple-specific change: Apple Clang (shipped with Xcode 16 on the macos-15 runners) defaults to C23, while upstream LLVM Clang on Linux still defaults to -std=gnu17 even in recent versions.

[crazywhalecc]

Using main branch I have no build error on my machine (macOS 15) but only if I use -std=c23 explicitly, I got error message.

And looks like ext-xlswriter -> libxlswriter -> minizip -> ioapi.c have K&R C function declaration too, which also need to be patched.

[henderkes]

I think the better course of action here is to explicitly pin to std=c17 until it's fixed upstream: viest/php-ext-xlswriter#559

[dunglas]

@crazywhalecc @henderkes You're right, ioapi.c also has K&R declarations. I've updated the PR to use -std=gnu17 instead of patching individual files — this covers all K&R occurrences in the bundled minizip. Added via both SPC_CMD_VAR_PHP_MAKE_EXTRA_CFLAGS (for static builds) and getExtraEnv() (for shared/phpize builds).

I've also opened a PR upstream to update libxlsxwriter: viest/php-ext-xlswriter#560 — once that's merged, this -std=gnu17 workaround can be removed.

[henderkes]

Should we use gnu17 here instead of c17?

[crazywhalecc]

It works fine on my mac.