From af1ed7d1b6a0cf0d15247ad2a07648cc8ce04f65 Mon Sep 17 00:00:00 2001
From: Michele Guerini Rocco <m.guerinirocco2@campus.unimib.it>
Date: Tue, 17 Oct 2023 11:01:51 +0200
Subject: [PATCH] Makefile: fix libgray.a with parallel building

ar does not support multiple builder writing to the same file.
This disable parallel building for .a targets.
See also "Archive Pitfalls" in the GNU Make manual.
---
 Makefile | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/Makefile b/Makefile
index 5a9ca7b..a4e0266 100644
--- a/Makefile
+++ b/Makefile
@@ -98,6 +98,9 @@ endif
 
 .PHONY: all clean install docs
 
+# Don't update archives in parallel, it's unsupported
+.NOTPARALLEL: $(LIBDIR)/libgray.a
+
 all: $(BINARIES) $(LIBRARIES)
 
 # Remove all generated files