Remove Boehm GC dependency

Makefile.config.in

@@ -1,5 +1,4 @@
 AR = @AR@
-BDW_GC_LIBS = @BDW_GC_LIBS@
 BUILD_SHARED_LIBS = @BUILD_SHARED_LIBS@
 CC = @CC@
 CFLAGS = @CFLAGS@

configure.ac

@@ -219,17 +219,6 @@ if test -n "$enable_s3"; then
 fi
 
 
-# Whether to use the Boehm garbage collector.
-AC_ARG_ENABLE(gc, AC_HELP_STRING([--enable-gc],
-  [enable garbage collection in the Nix expression evaluator (requires Boehm GC) [default=no]]),
-  gc=$enableval, gc=no)
-if test "$gc" = yes; then
-  PKG_CHECK_MODULES([BDW_GC], [bdw-gc])
-  CXXFLAGS="$BDW_GC_CFLAGS $CXXFLAGS"
-  AC_DEFINE(HAVE_BOEHMGC, 1, [Whether to use the Boehm garbage collector.])
-fi
-
-
 # documentation generation switch
 AC_ARG_ENABLE(doc-gen, AC_HELP_STRING([--disable-doc-gen],
   [disable documentation generation]),

doc/manual/installation/prerequisites-source.xml

@@ -50,14 +50,6 @@
   or higher.  If your distribution does not provide it, please install
   it from <link xlink:href="http://www.sqlite.org/" />.</para></listitem>
 
-  <listitem><para>The <link
-  xlink:href="http://www.hboehm.info/gc/">Boehm
-  garbage collector</link> to reduce the evaluator’s memory
-  consumption (optional).  To enable it, install
-  <literal>pkgconfig</literal> and the Boehm garbage collector, and
-  pass the flag <option>--enable-gc</option> to
-  <command>configure</command>.</para></listitem>
-
   <listitem><para>The <literal>boost</literal> library of version
   1.66.0 or higher. It can be obtained from the official web site
   <link xlink:href="https://www.boost.org/" />.</para></listitem>

release-common.nix

@@ -50,7 +50,7 @@ rec {
   buildDeps =
     [ curl
       bzip2 xz brotli editline
-      openssl pkgconfig sqlite boehmgc
+      openssl pkgconfig sqlite
       boost
 
       # Tests

src/libexpr/eval.cc

@@ -177,16 +177,6 @@ static Symbol getName(const AttrName & name, EvalState & state, Env & env)
 }
 
 
-static bool gcInitialised = false;
-
-void initGC()
-{
-    if (gcInitialised) return;
-
-    gcInitialised = true;
-}
-
-
 /* Very hacky way to parse $NIX_PATH, which is colon-separated, but
    can contain URLs (e.g. "nixpkgs=https://bla...:foo=https://"). */
 static Strings parseNixPath(const string & s)
@@ -258,11 +248,7 @@ EvalState::EvalState(const Strings & _searchPath, ref<Store> store)
 {
     countCalls = getEnv("NIX_COUNT_CALLS", "0") != "0";
 
-    assert(gcInitialised);
-
-#if 0
     static_assert(sizeof(Env) <= 16, "environment must be <= 16 bytes");
-#endif
 
     /* Initialise the Nix expression search path. */
     if (!evalSettings.pureEval) {

src/libexpr/eval.hh

@@ -97,10 +97,6 @@ typedef std::pair<std::string, std::string> SearchPathElem;
 typedef std::list<SearchPathElem> SearchPath;
 
 
-/* Initialise the Boehm GC, if applicable. */
-void initGC();
-
-
 class EvalState
 {
 public:

src/nix/main.cc

@@ -75,7 +75,6 @@ void mainWrapped(int argc, char * * argv)
     }
 
     initNix();
-    initGC();
 
     programPath = argv[0];
     string programName = baseNameOf(programPath);