Quick comptime interpreter fix, place it behind an option (#761)

* Quick fix

* Add config option

README.md

@@ -125,6 +125,7 @@ The following options are currently available.
 |`max_detail_length`|`usize`|`1024 * 1024`| The detail field of completions is truncated to be no longer than this (in bytes).
 | `skip_std_references` | `bool` | `false` | When true, skips searching for references in std. Improves lookup speed for functions in user's code. Renaming and go-to-definition will continue to work as is.
 | `highlight_global_var_declarations` | `bool` | `false` | Whether to highlight global var declarations.
+| `use_comptime_interpreter` | `bool` | `false` | Whether to use the comptime interpreter.
 
 ### Per-build Configuration Options
 

schema.json

@@ -99,6 +99,11 @@
             "description": "Whether to highlight global var declarations",
             "type": "boolean",
             "default": "false"
+        },
+        "use_comptime_interpreter": {
+            "description": "Whether to use the comptime interpreter",
+            "type": "boolean",
+            "default": "false"
         }
     }
 } 

src/ComptimeInterpreter.zig

@@ -1421,7 +1421,7 @@ pub fn call(
     const tree = interpreter.getHandle().tree;
     const tags = tree.nodes.items(.tag);
 
-    std.debug.assert(tags[func_node_idx] == .fn_decl);
+    if (tags[func_node_idx] != .fn_decl) return error.CriticalAstFailure;
 
     // TODO: Make argument scope to evaluate arguments in
     var fn_scope = try interpreter.newScope(scope, func_node_idx);

src/Config.zig

@@ -79,6 +79,9 @@ builtin_path: ?[]const u8 = null,
 /// Whether to highlight global var declarations.
 highlight_global_var_declarations: bool = false,
 
+/// Whether to use the comptime interpreter
+use_comptime_interpreter: bool = false,
+
 pub fn loadFromFile(allocator: std.mem.Allocator, file_path: []const u8) ?Config {
     const tracy_zone = tracy.trace(@src());
     defer tracy_zone.end();

src/analysis.zig

@@ -745,7 +745,7 @@ pub fn resolveTypeOfNodeInternal(store: *DocumentStore, arena: *std.heap.ArenaAl
                 const body = decl.handle.tree.nodes.items(.data)[decl_node].rhs;
                 if (try resolveReturnType(store, arena, fn_decl, decl.handle, bound_type_params, if (has_body) body else null)) |ret| {
                     return ret;
-                } else {
+                } else if (store.config.use_comptime_interpreter) {
                     // TODO: Better case-by-case; we just use the ComptimeInterpreter when all else fails,
                     // probably better to use it more liberally
                     // TODO: Handle non-isolate args; e.g. `const T = u8; TypeFunc(T);`