From a12bf2d75314c2e3032b017f41e0785e0ed733d9 Mon Sep 17 00:00:00 2001
From: Jim Blandy <jimb@red-bean.com>
Date: Wed, 29 Jul 2020 16:14:51 -0700
Subject: [PATCH] Fancier TBB (Threaded Building Blocks) detection.

Update documentation to mention that it's needed.
---
 profiler/build/unix/build.mk | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/profiler/build/unix/build.mk b/profiler/build/unix/build.mk
index 101141f6..865c41a0 100644
--- a/profiler/build/unix/build.mk
+++ b/profiler/build/unix/build.mk
@@ -25,8 +25,14 @@ else
 	LIBS += $(shell pkg-config --libs gtk+-2.0) -lGL
 endif
 
-TBB := $(shell ld -ltbb -o /dev/null 2>/dev/null; echo $$?)
-ifeq ($(TBB),0)
+# Tracy does not use TBB directly, but the implementation of parallel algorithms
+# in some versions of libstdc++ depends on TBB. When it does, you must
+# explicitly link against -ltbb.
+#
+# Some distributions have pgk-config files for TBB, others don't.
+ifeq (0,$(shell pkg-config --libs tbb >/dev/null 2>&1; echo $$?))
+	LIBS += $(shell pkg-config --libs tbb)
+else ifeq (0,$(shell ld -ltbb -o /dev/null 2>/dev/null; echo $$?))
 	LIBS += -ltbb
 endif