Remove check for U gate in map_gate_ids

* This requires modifying the external parser crate.
* Depend temporarily on the branch of the parser with this modification.
* Make another change required by other upstream improvments.
* Cargo config files are changed because of above changes.

crates/qasm3/Cargo.toml

@@ -18,4 +18,4 @@ extension-module = ["pyo3/extension-module"]
 pyo3.workspace = true
 indexmap.workspace = true
 hashbrown.workspace = true
-oq3_semantics = { git = "https://github.com/jlapeyre/openqasm3_parser", branch = "update-for-qiskit-importer"}
+oq3_semantics = { git = "https://github.com/jlapeyre/openqasm3_parser", branch = "no-U-in-gate-list"}

crates/qasm3/src/build.rs

@@ -231,10 +231,6 @@ impl BuilderState {
     // Gates mapped via CustomGates will not raise an exception.
     fn map_gate_ids(&mut self, _py: Python, ast_symbols: &SymbolTable) -> PyResult<()> {
         for (name, name_id, defined_num_params, defined_num_qubits) in ast_symbols.gates().iter() {
-            if *name == "U" {
-                // The sole built in gate. `gphase` is treated specially.
-                continue;
-            }
             let pygate = self.pygates.get(*name).ok_or_else(|| {
                 QASM3ImporterError::new_err(format!("can't handle non-built-in gate: '{}'", name))
             })?;

crates/qasm3/src/expr.rs

@@ -241,11 +241,11 @@ pub fn eval_qarg(
     qarg: &asg::GateOperand,
 ) -> PyResult<BroadcastItem> {
     match qarg {
-        asg::GateOperand::Identifier(iden) => broadcast_bits_for_identifier(
+        asg::GateOperand::Identifier(symbol) => broadcast_bits_for_identifier(
             py,
             &our_symbols.qubits,
             &our_symbols.qregs,
-            iden.symbol().as_ref().unwrap(),
+            symbol.as_ref().unwrap(),
         ),
         asg::GateOperand::IndexedIdentifier(indexed) => {
             let iden_symbol = indexed.identifier().as_ref().unwrap();