accounts/abi/bind: correctly handle structs used only as constructor params (#23940)

The `structs` map is populated by iterating over all methods except the constructor, which results in a nil-pointer dereference.

I've first reproduced the problem with a new test and then implemented the fix.

Co-authored-by: Arran Schlosberg <me@arranschlosberg.com>

accounts/abi/bind/bind.go

@@ -88,6 +88,13 @@ func Bind(types []string, abis []string, bytecodes []string, fsigs []map[string]
 			transactIdentifiers = make(map[string]bool)
 			eventIdentifiers    = make(map[string]bool)
 		)
+
+		for _, input := range evmABI.Constructor.Inputs {
+			if hasStruct(input.Type) {
+				bindStructType[lang](input.Type, structs)
+			}
+		}
+
 		for _, original := range evmABI.Methods {
 			// Normalize the method for capital cases and non-anonymous inputs/outputs
 			normalized := original

accounts/abi/bind/bind_test.go

@@ -1911,6 +1911,50 @@ var bindTests = []struct {
 		nil,
 		nil,
 	},
+	{
+		name: `ConstructorWithStructParam`,
+		contract: `
+		pragma solidity >=0.8.0 <0.9.0;
+		
+		contract ConstructorWithStructParam {
+			struct StructType {
+				uint256 field;
+			}
+		
+			constructor(StructType memory st) {}
+		}
+		`,
+		bytecode: []string{`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`},
+		abi:      []string{`[{"inputs":[{"components":[{"internalType":"uint256","name":"field","type":"uint256"}],"internalType":"struct ConstructorWithStructParam.StructType","name":"st","type":"tuple"}],"stateMutability":"nonpayable","type":"constructor"}]`},
+		imports: `
+			"math/big"
+
+			"github.com/ethereum/go-ethereum/accounts/abi/bind"
+			"github.com/ethereum/go-ethereum/accounts/abi/bind/backends"
+			"github.com/ethereum/go-ethereum/core"
+			"github.com/ethereum/go-ethereum/crypto"
+			"github.com/ethereum/go-ethereum/eth/ethconfig"
+		`,
+		tester: `
+			var (
+				key, _  = crypto.GenerateKey()
+				user, _ = bind.NewKeyedTransactorWithChainID(key, big.NewInt(1337))
+				sim     = backends.NewSimulatedBackend(core.GenesisAlloc{user.From: {Balance: big.NewInt(1000000000000000000)}}, ethconfig.Defaults.Miner.GasCeil)
+			)
+			defer sim.Close()
+
+			_, tx, _, err := DeployConstructorWithStructParam(user, sim, ConstructorWithStructParamStructType{Field: big.NewInt(42)})
+			if err != nil {
+				t.Fatalf("DeployConstructorWithStructParam() got err %v; want nil err", err)
+			}
+			sim.Commit()
+			
+			if _, err = bind.WaitDeployed(nil, sim, tx); err != nil {
+				t.Logf("Deployment tx: %+v", tx)
+				t.Errorf("bind.WaitDeployed(nil, %T, <deployment tx>) got err %v; want nil err", sim, err)
+			}
+		`,
+	},
 }
 
 // Tests that packages generated by the binder can be successfully compiled and
@@ -1934,6 +1978,7 @@ func TestGolangBindings(t *testing.T) {
 	}
 	// Generate the test suite for all the contracts
 	for i, tt := range bindTests {
+		t.Run(tt.name, func(t *testing.T) {
 			var types []string
 			if tt.types != nil {
 				types = tt.types
@@ -1964,6 +2009,7 @@ func TestGolangBindings(t *testing.T) {
 			if err := ioutil.WriteFile(filepath.Join(pkg, strings.ToLower(tt.name)+"_test.go"), []byte(code), 0600); err != nil {
 				t.Fatalf("test %d: failed to write tests: %v", i, err)
 			}
+		})
 	}
 	// Convert the package to go modules and use the current source for go-ethereum
 	moder := exec.Command(gocmd, "mod", "init", "bindtest")