From 5a1114ecdbbd115ec8aeb1a98326d793ff3e8058 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <eelco.dolstra@logicblox.com>
Date: Sat, 23 Nov 2013 20:19:36 +0000
Subject: [PATCH] Drop the dependency on libgc in libmain

Instead, libexpr now depends on libgc.  This means commands like
nix-store that don't do any evaluation no longer require libgc.
---
 src/libexpr/Makefile.new |  5 +++++
 src/libexpr/eval.cc      | 17 +++++++++++++++++
 src/libmain/Makefile.new |  2 --
 src/libmain/shared.cc    | 20 --------------------
 4 files changed, 22 insertions(+), 22 deletions(-)

diff --git a/src/libexpr/Makefile.new b/src/libexpr/Makefile.new
index ded112107f..cbae11c53c 100644
--- a/src/libexpr/Makefile.new
+++ b/src/libexpr/Makefile.new
@@ -9,6 +9,11 @@ libexpr_SOURCES = \
 
 libexpr_LIBS = libutil libstore libformat
 
+# The dependency on libgc must be propagated (i.e. meaning that
+# programs/libraries that use libexpr must explicitly pass -lgc),
+# because inline functions in libexpr's header files call libgc.
+libexpr_LDFLAGS_PROPAGATED = $(BDW_GC_LIBS)
+
 $(d)/parser-tab.cc $(d)/parser-tab.hh: $(d)/parser.y
 	bison -v -o $(libexpr_DIR)/parser-tab.cc $< -d
 
diff --git a/src/libexpr/eval.cc b/src/libexpr/eval.cc
index e4a0d7fd2b..12c6aa8dcd 100644
--- a/src/libexpr/eval.cc
+++ b/src/libexpr/eval.cc
@@ -129,6 +129,14 @@ string showType(const Value & v)
 }
 
 
+/* Called when the Boehm GC runs out of memory. */
+static void * oomHandler(size_t requested)
+{
+    /* Convert this to a proper C++ exception. */
+    throw std::bad_alloc();
+}
+
+
 EvalState::EvalState()
     : sWith(symbols.create("<with>"))
     , sOutPath(symbols.create("outPath"))
@@ -158,6 +166,14 @@ EvalState::EvalState()
 #if HAVE_BOEHMGC
     static bool gcInitialised = false;
     if (!gcInitialised) {
+
+        /* Initialise the Boehm garbage collector.  This isn't
+           necessary on most platforms, but for portability we do it
+           anyway. */
+        GC_INIT();
+
+        GC_oom_fn = oomHandler;
+
         /* Set the initial heap size to something fairly big (25% of
            physical RAM, up to a maximum of 384 MiB) so that in most
            cases we don't need to garbage collect at all.  (Collection
@@ -181,6 +197,7 @@ EvalState::EvalState()
             debug(format("setting initial heap size to %1% bytes") % size);
             GC_expand_hp(size);
         }
+
         gcInitialised = true;
     }
 #endif
diff --git a/src/libmain/Makefile.new b/src/libmain/Makefile.new
index 86323dbd48..6ca49d5838 100644
--- a/src/libmain/Makefile.new
+++ b/src/libmain/Makefile.new
@@ -5,5 +5,3 @@ libmain_DIR := $(d)
 libmain_SOURCES = shared.cc stack.cc
 
 libmain_LIBS = libstore libutil libformat
-
-libmain_LDFLAGS_PROPAGATED = $(BDW_GC_LIBS)
diff --git a/src/libmain/shared.cc b/src/libmain/shared.cc
index b0b69f7f61..8df2a7f52a 100644
--- a/src/libmain/shared.cc
+++ b/src/libmain/shared.cc
@@ -15,10 +15,6 @@
 #include <unistd.h>
 #include <signal.h>
 
-#if HAVE_BOEHMGC
-#include <gc/gc.h>
-#endif
-
 
 namespace nix {
 
@@ -231,14 +227,6 @@ static void initAndRun(int argc, char * * argv)
 }
 
 
-/* Called when the Boehm GC runs out of memory. */
-static void * oomHandler(size_t requested)
-{
-    /* Convert this to a proper C++ exception. */
-    throw std::bad_alloc();
-}
-
-
 void showManPage(const string & name)
 {
     string cmd = "man " + name;
@@ -268,14 +256,6 @@ int main(int argc, char * * argv)
 
     std::ios::sync_with_stdio(false);
 
-#if HAVE_BOEHMGC
-    /* Initialise the Boehm garbage collector.  This isn't necessary
-       on most platforms, but for portability we do it anyway. */
-    GC_INIT();
-
-    GC_oom_fn = oomHandler;
-#endif
-
     try {
         try {
             initAndRun(argc, argv);