Change AST to match the functionality of the Driver

doc/architecture.md

@@ -1,12 +1,15 @@
-# Architecture Note: Omitted Keywords
+# Architecture Notes
+
+## Omitted Keywords
+
 The `crate` and `super` keywords were not added to the compiler because they
 are unnecessary at this stage. Typically, they are used to resolve relative
 paths during import parsing. However, in our architecture, the prefix before
 the first `::` in a `use` statement is always an dependency root path. Since all
 dependency root paths are unique and strictly bound to specific paths, the resolver
 can always unambiguously resolve the path without needing relative pointers.
 
-# Architecture Note: Namespace Separation in SimplicityHL
+## Namespace Separation in SimplicityHL
 
 SimplicityHL uses distinct namespaces for types and values. This allows the same identifier to refer to different things depending on where it appears in the code — the compiler determines the correct interpretation from syntactic context, with no risk of collision.
 
@@ -19,3 +22,10 @@ fn main() {
     assert!(foo());     // value namespace - function
 }
 ```
+
+## The "main" identifier in aliases
+
+In SimplicityHL, the string "main" is reserved exclusively for the program's entry point function.
+While a `TypeAlias` is technically allowed to use this name, we explicitly forbid aliasing imports
+to "main" using the `as` keyword. This avoids complicating the compiler's resolution logic and
+prevents accidental shadowing of the entry point.

fuzz/fuzz_targets/compile_parse_tree.rs

@@ -3,16 +3,27 @@
 #[cfg(any(fuzzing, test))]
 fn do_test(data: &[u8]) {
     use arbitrary::Arbitrary;
+    use std::sync::Arc;
 
-    use simplicityhl::error::WithContent;
-    use simplicityhl::{ast, named, parse, ArbitraryOfType, Arguments};
+    use simplicityhl::error::{ErrorCollector, WithContent};
+    use simplicityhl::{ast, driver, named, parse, ArbitraryOfType, Arguments};
 
     let mut u = arbitrary::Unstructured::new(data);
     let parse_program = match parse::Program::arbitrary(&mut u) {
         Ok(x) => x,
         Err(_) => return,
     };
-    let ast_program = match ast::Program::analyze(&parse_program) {
+
+    let mut error_handler = ErrorCollector::new();
+    let driver_program = if let Some(program) =
+        driver::Program::from_parse(&parse_program, Arc::from(""), &mut error_handler)
+    {
+        program
+    } else {
+        return;
+    };
+
+    let ast_program = match ast::Program::analyze(&driver_program) {
         Ok(x) => x,
         Err(_) => return,
     };