[PATCH v2] config.mak.uname: avoid macOS linker warning on Xcode 16.3+

["Harald Nordgren via GitGitGadget" <gitgitgadget@gmail.com>]

From: Harald Nordgren <haraldnordgren@gmail.com>

Building on macOS with Xcode 16.3 or newer emits:

    ld: warning: reducing alignment of section __DATA,__common
    from 0x8000 to 0x4000 because it exceeds segment maximum
    alignment

Pass -fno-common when "ld -v" reports ld-1167 or newer, so tentative
definitions of large arrays go into BSS instead of __DATA,__common.

Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
---
    pkt-line: initialize packet_buffer to avoid macOS linker warning
    
     * Check MacOS ld version instead
       (https://en.wikipedia.org/wiki/Xcode#Xcode_15.0_-_16.x_(since_visionOS_support)_2)
    
    Parsing output of
    
    ❯ ld -v
    @(#)PROGRAM:ld PROJECT:ld-1267
    BUILD 18:30:29 Apr 22 2026
    configured to support archs: armv6 armv7 armv7s arm64 arm64e arm64_32 i386 x86_64 x86_64h armv6m armv7k armv7m armv7em armv8m.main armv8.1m.main
    will use ld-classic for: armv6 armv7 armv7s i386 armv6m armv7k armv7m armv7em
    LTO support using: LLVM version 21.0.0 (static support for 30, runtime is 30)
    TAPI support using: Apple TAPI version 21.0.0 (tapi-2100.0.2.6)
    

Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-git-2313%2FHaraldNordgren%2Fpkt-line-init-buffer-v2
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-git-2313/HaraldNordgren/pkt-line-init-buffer-v2
Pull-Request: https://github.com/git/git/pull/2313

Range-diff vs v1:

 1:  1c1c66d85b < -:  ---------- pkt-line: initialize packet_buffer to avoid macOS linker warning
 -:  ---------- > 1:  0e660a346e config.mak.uname: avoid macOS linker warning on Xcode 16.3+


 config.mak.uname | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/config.mak.uname b/config.mak.uname
index ce5e7de779..d4d55cb324 100644
--- a/config.mak.uname
+++ b/config.mak.uname
@@ -163,6 +163,12 @@ ifeq ($(uname_S),Darwin)
 		NEEDS_GOOD_LIBICONV = UnfortunatelyYes
         endif
 
+	# Silence Xcode 16.3+ linker warning about __DATA,__common alignment.
+	LD_MAJOR_VERSION = $(shell ld -v 2>&1 | sed -n 's/.*PROJECT:ld-\([0-9]*\).*/\1/p')
+        ifeq ($(shell test "$(LD_MAJOR_VERSION)" -ge 1167 && echo 1),1)
+		BASIC_CFLAGS += -fno-common
+        endif
+
 	# The builtin FSMonitor on MacOS builds upon Simple-IPC.  Both require
 	# Unix domain sockets and PThreads.
         ifndef NO_PTHREADS

base-commit: c69baaf57ba26cf117c2b6793802877f19738b0d
-- 
gitgitgadget