Introduce CompilationResult struct

This commit introduces the `CompilationResult` struct to encapsulate the
outcome of a compilation pass. It holds either a successfully compiled
`TypedNode` or a `Diagnostics` object containing errors. Helper methods
for creating success or error results and for converting to a `Result`
are also included. This improves error handling and clarity in the
compilation process.

src/ast/compiler/mod.rs

@@ -19,3 +19,39 @@ pub use optimizer::*;
 pub use specializer::*;
 pub use lowering::*;
 pub use type_checker::*;
+
+use crate::ast::diagnostics::Diagnostics;
+
+/// The result of a compilation pass: either a typed AST or a set of diagnostics.
+pub struct CompilationResult {
+    pub ast: Option<TypedNode>,
+    pub diagnostics: Diagnostics,
+}
+
+impl CompilationResult {
+    pub fn success(ast: TypedNode) -> Self {
+        Self {
+            ast: Some(ast),
+            diagnostics: Diagnostics::new(),
+        }
+    }
+
+    pub fn error(msg: impl Into<String>) -> Self {
+        let mut diag = Diagnostics::new();
+        diag.push_error(msg, None);
+        Self {
+            ast: None,
+            diagnostics: diag,
+        }
+    }
+
+    pub fn into_result(self) -> Result<TypedNode, String> {
+        if self.diagnostics.has_errors() {
+            Err(self.diagnostics.format_errors())
+        } else if let Some(ast) = self.ast {
+            Ok(ast)
+        } else {
+            Err("Compilation failed without diagnostics".to_string())
+        }
+    }
+}