fix(soroban): reject unsupported ABI types before codegen

Move unsupported Soroban ABI validation into the Soroban codegen path before dispatch wrapper generation, encoder/decoder lowering, spec emission, and LLVM emission can hit unsupported constructs.

Add diagnostics for unsupported Soroban external/public ABI surfaces, including unsupported bytes parameters, bytes/string/struct/array returns, public accessor returns, multiple external returns, unsupported event argument types, and internal string-helper patterns that could otherwise reach LLVM/Inkwell failures.

Target-gate the Soroban validation and early returns so non-Soroban diagnostic accumulation remains unchanged.

This avoids user-triggerable panic!, todo!, unimplemented!, and LLVM assertion paths from #1897 while keeping supported event emission, public string accessors, internal bytes helpers, and non-Soroban targets unaffected.

Signed-off-by: mohamedbasuony <mohamedbasuony@aucegypt.edu>

Author: mohamedbasuony

src/codegen/mod.rs

@@ -302,6 +302,18 @@ fn contract(contract_no: usize, ns: &mut Namespace, opt: &Options) {
     if !ns.diagnostics.any_errors() && ns.contracts[contract_no].instantiable {
         layout(contract_no, ns);
 
+        if ns.target == Target::Soroban {
+            soroban::validate_accessor_abi_types(contract_no, ns);
+            if ns.diagnostics.any_errors() {
+                return;
+            }
+
+            soroban::validate_event_abi_types(contract_no, ns);
+            if ns.diagnostics.any_errors() {
+                return;
+            }
+        }
+
         let mut cfg_no = 0;
         let mut all_cfg = Vec::new();
 
@@ -359,6 +371,13 @@ fn contract(contract_no: usize, ns: &mut Namespace, opt: &Options) {
             ns.contracts[contract_no].default_constructor = Some((func, cfg_no));
         }
 
+        if ns.target == Target::Soroban {
+            soroban::validate_abi_types(&all_cfg, ns);
+            if ns.diagnostics.any_errors() {
+                return;
+            }
+        }
+
         for mut dispatch_cfg in function_dispatch(contract_no, &mut all_cfg, ns, opt) {
             optimize_and_check_cfg(&mut dispatch_cfg, ns, ASTFunction::None, opt);
             all_cfg.push(dispatch_cfg);