sage.lib, sage.test: clang-19 / darwin fixes (#370822)

pkgs/by-name/sa/sage/sage-tests.nix

@@ -49,6 +49,14 @@ stdenv.mkDerivation {
     makeWrapper "${sage-with-env}/bin/sage" "$out/bin/sage"
   '';
 
+  env = lib.optionalAttrs stdenv.hostPlatform.isDarwin {
+    # prevent warnings about assigning LC_* to "C" resulting in broken tests
+    # when run in darwin sandbox
+    LC_ALL = "en_US.UTF-8";
+  };
+
+  # allow singular tests to pass in darwin sandbox
+  __darwinAllowLocalNetworking = true;
   doInstallCheck = true;
   installCheckPhase = ''
     export HOME="$TMPDIR/sage-home"

pkgs/by-name/sa/sage/sagelib.nix

@@ -1,4 +1,6 @@
 {
+  lib,
+  stdenv,
   sage-src,
   env-locations,
   python,
@@ -118,6 +120,13 @@ buildPythonPackage rec {
     readline
   ];
 
+  env = lib.optionalAttrs stdenv.cc.isClang {
+    # code tries to assign a unsigned long to an int in an initialized list
+    # leading to this error.
+    # https://github.com/sagemath/sage/pull/39249
+    NIX_CFLAGS_COMPILE = "-Wno-error=c++11-narrowing-const-reference";
+  };
+
   propagatedBuildInputs = [
     # native dependencies (TODO: determine which ones need to be propagated)
     blas