nix-flake: Add shell definition (#954)

Initialized flake file and added development shell definition.
Exporting of default compiler flags is moved to makefile.

Referenced issue: https://github.com/codex-storage/nim-codex/issues/940

Signed-off-by: markoburcul <marko@status.im>

Makefile

@@ -40,6 +40,9 @@ DOCKER_IMAGE_NIM_PARAMS ?= -d:chronicles_colors:none -d:insecure
 
 LINK_PCRE := 0
 
+CXXFLAGS ?= -std=c++17 -mssse3
+export CXXFLAGS
+
 # we don't want an error here, so we can handle things later, in the ".DEFAULT" target
 -include $(BUILD_SYSTEM_DIR)/makefiles/variables.mk
 

flake.lock

@@ -0,0 +1,27 @@
+{
+  "nodes": {
+    "nixpkgs": {
+      "locked": {
+        "lastModified": 1729449015,
+        "narHash": "sha256-Gf04dXB0n4q0A9G5nTGH3zuMGr6jtJppqdeljxua1fo=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "89172919243df199fe237ba0f776c3e3e3d72367",
+        "type": "github"
+      },
+      "original": {
+        "owner": "NixOS",
+        "ref": "nixos-24.05",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "root": {
+      "inputs": {
+        "nixpkgs": "nixpkgs"
+      }
+    }
+  },
+  "root": "root",
+  "version": 7
+}

flake.nix

@@ -0,0 +1,35 @@
+{
+  description = "Codex build flake";
+  
+  inputs = {
+    nixpkgs.url = "github:NixOS/nixpkgs/nixos-24.05";
+  };
+
+  outputs = { self, nixpkgs }:
+    let
+      supportedSystems = [
+        "x86_64-linux" "aarch64-linux"
+        "x86_64-darwin" "aarch64-darwin"
+      ];
+      forAllSystems = f: nixpkgs.lib.genAttrs supportedSystems (system: f system);
+      pkgsFor = forAllSystems (system: import nixpkgs { inherit system; });
+    in rec {
+      devShells = forAllSystems (system: let
+        pkgs = pkgsFor.${system};
+        inherit (pkgs) lib stdenv mkShell;
+      in {
+        default = mkShell.override { stdenv = pkgs.gcc11Stdenv; } {
+          buildInputs = with pkgs; [
+              # General
+              git pkg-config openssl lsb-release
+              # Build
+              rustc cargo nimble gcc11 cmake nim-unwrapped-1
+              # Libraries
+              gmp llvmPackages.openmp
+              # Tests
+              nodejs_18
+          ];
+        };
+      });
+    };
+}