Parameterize program solving on a FunctionKind

This new flag determines whether we should introduce a new kind to
represent lambda sets, or whether lambdas should be erased. The latter
is not yet implemented.

crates/compiler/test_derive/src/util.rs

@@ -3,7 +3,10 @@ use std::path::PathBuf;
 
 use bumpalo::Bump;
 use roc_packaging::cache::RocCacheDir;
-use roc_solve::module::{SolveConfig, SolveOutput};
+use roc_solve::{
+    module::{SolveConfig, SolveOutput},
+    FunctionKind,
+};
 use ven_pretty::DocAllocator;
 
 use roc_can::{
@@ -520,6 +523,7 @@ where
         path.parent().unwrap().to_path_buf(),
         Default::default(),
         target_info,
+        FunctionKind::LambdaSet,
         roc_reporting::report::RenderTarget::ColorTerminal,
         roc_reporting::report::DEFAULT_PALETTE,
         RocCacheDir::Disallowed,