nix: fix abc

flake.nix

@@ -12,19 +12,24 @@
         pkgs = import nixpkgs {
           inherit system;
         };
+        # TODO: don't override src when ./abc is empty
+        # which happens when the command used is `nix build` and not `nix build ?submodules=1`
+        abc-verifier = pkgs.abc-verifier.overrideAttrs(x: y: {src = ./abc;});
         customYosys = pkgs.clangStdenv.mkDerivation {
           name = "yosys";
           src = ./. ;
           buildInputs = with pkgs; [ clang bison flex libffi tcl readline python3 llvmPackages.libcxxClang zlib git pkg-configUpstream ];
           checkInputs = with pkgs; [ gtest ];
-          propagatedBuildInputs = with pkgs; [ abc-verifier ];
+          propagatedBuildInputs = [ abc-verifier ];
           preConfigure = "make config-clang";
           checkTarget = "test";
           installPhase = ''
-            make install PREFIX=$out
+            make install PREFIX=$out ABCEXTERNAL=yosys-abc
+            ln -s ${abc-verifier}/bin/abc $out/bin/yosys-abc
           '';
+          # TODO: this way abc actually doesn't work in yosys
 					buildPhase = ''
-          make -j$(nproc)
+            make -j$(nproc) ABCEXTERNAL=yosys-abc
           '';
           meta = with pkgs.lib; {
             description = "Yosys Open SYnthesis Suite";