Fix clang build

flake.lock

@@ -1,5 +1,22 @@
 {
   "nodes": {
+    "lowdown-src": {
+      "flake": false,
+      "locked": {
+        "lastModified": 1598296217,
+        "narHash": "sha256-ha7lyNY1d8m+osmDpPc9f/bfZ3ZC1IVIXwfyklSWg8I=",
+        "owner": "edolstra",
+        "repo": "lowdown",
+        "rev": "c7a4e715af1e233080842db82d15b261cb74cb28",
+        "type": "github"
+      },
+      "original": {
+        "owner": "edolstra",
+        "ref": "no-structs-in-anonymous-unions",
+        "repo": "lowdown",
+        "type": "github"
+      }
+    },
     "nixpkgs": {
       "locked": {
         "lastModified": 1591633336,
@@ -17,10 +34,11 @@
     },
     "root": {
       "inputs": {
+        "lowdown-src": "lowdown-src",
         "nixpkgs": "nixpkgs"
       }
     }
   },
   "root": "root",
-  "version": 6
+  "version": 7
 }

flake.nix

@@ -2,8 +2,9 @@
   description = "The purely functional package manager";
 
   inputs.nixpkgs.url = "nixpkgs/nixos-20.03-small";
+  inputs.lowdown-src = { url = "github:edolstra/lowdown/no-structs-in-anonymous-unions"; flake = false; };
 
-  outputs = { self, nixpkgs }:
+  outputs = { self, nixpkgs, lowdown-src }:
 
     let
 
@@ -188,10 +189,14 @@
         lowdown = with final; stdenv.mkDerivation {
           name = "lowdown-0.7.1";
 
+          /*
           src = fetchurl {
             url = https://kristaps.bsd.lv/lowdown/snapshots/lowdown-0.7.1.tar.gz;
             hash = "sha512-1daoAQfYD0LdhK6aFhrSQvadjc5GsSPBZw0fJDb+BEHYMBLjqiUl2A7H8N+l0W4YfGKqbsPYSrCy4vct+7U6FQ==";
           };
+          */
+
+          src = lowdown-src;
 
           outputs = [ "out" "dev" ];
 

src/nix/local.mk

@@ -16,7 +16,7 @@ nix_SOURCES := \
   $(wildcard src/nix-store/*.cc) \
 
 # -fpermissive is needed by lowdown.
-nix_CXXFLAGS += -I src/libutil -I src/libstore -I src/libfetchers -I src/libexpr -I src/libmain -fpermissive
+nix_CXXFLAGS += -I src/libutil -I src/libstore -I src/libfetchers -I src/libexpr -I src/libmain
 
 nix_LIBS = libexpr libmain libfetchers libstore libutil