treewide: Support builds with ASAN, enable in CI

Enables builds with ASAN to catch memory corruption
bugs faster and in CI. This is an incredibly valuable
instrument that must be used as much as possible.

Somewhat based on jade's work from Lix, though there's a lot that
we have to do differently:

19ae87e5ce

Co-authored-by: Jade Lovelace <lix@jade.fyi>

ci/gha/tests/default.nix

@@ -24,16 +24,7 @@ let
   enableSanitizersLayer = finalAttrs: prevAttrs: {
     mesonFlags =
       (prevAttrs.mesonFlags or [ ])
-      ++ [
-        # Run all tests with UBSAN enabled. Running both with ubsan and
-        # without doesn't seem to have much immediate benefit for doubling
-        # the GHA CI workaround.
-        #
-        # TODO: Work toward enabling "address,undefined" if it seems feasible.
-        # This would maybe require dropping Boost coroutines and ignoring intentional
-        # memory leaks with detect_leaks=0.
-        (lib.mesonOption "b_sanitize" "undefined")
-      ]
+      ++ [ (lib.mesonOption "b_sanitize" "address,undefined") ]
       ++ (lib.optionals stdenv.cc.isClang [
         # https://www.github.com/mesonbuild/meson/issues/764
         (lib.mesonBool "b_lundef" false)
@@ -71,8 +62,12 @@ rec {
   nixComponentsInstrumented = nixComponents.overrideScope (
     final: prev: {
       nix-store-tests = prev.nix-store-tests.override { withBenchmarks = true; };
+      # Boehm is incompatible with ASAN.
+      nix-expr = prev.nix-expr.override { enableGC = !withSanitizers; };
 
       mesonComponentOverrides = lib.composeManyExtensions componentOverrides;
+      # Unclear how to make Perl bindings work with a dynamically linked ASAN.
+      nix-perl-bindings = if withSanitizers then null else prev.nix-perl-bindings;
     }
   );