accounts/abi: resolve name conflict for methods starting with a number (#26999)

This adds logic to prepend 'M' or 'E' to Solidity identifiers when they would
otherwise violate Go identifier naming rules.

Closes #26972

---------
Co-authored-by: Martin Holst Swende <martin@swende.se>
Co-authored-by: Sina Mahmoodi <itz.s1na@gmail.com>

accounts/abi/bind/bind.go

@@ -133,12 +133,19 @@ func Bind(types []string, abis []string, bytecodes []string, fsigs []map[string]
 			// Normalize the method for capital cases and non-anonymous inputs/outputs
 			normalized := original
 			normalizedName := methodNormalizer[lang](alias(aliases, original.Name))
-
 			// Ensure there is no duplicated identifier
 			var identifiers = callIdentifiers
 			if !original.IsConstant() {
 				identifiers = transactIdentifiers
 			}
+			// Name shouldn't start with a digit. It will make the generated code invalid.
+			if len(normalizedName) > 0 && unicode.IsDigit(rune(normalizedName[0])) {
+				normalizedName = fmt.Sprintf("M%s", normalizedName)
+				normalizedName = abi.ResolveNameConflict(normalizedName, func(name string) bool {
+					_, ok := identifiers[name]
+					return ok
+				})
+			}
 			if identifiers[normalizedName] {
 				return "", fmt.Errorf("duplicated identifier \"%s\"(normalized \"%s\"), use --alias for renaming", original.Name, normalizedName)
 			}
@@ -182,6 +189,14 @@ func Bind(types []string, abis []string, bytecodes []string, fsigs []map[string]
 
 			// Ensure there is no duplicated identifier
 			normalizedName := methodNormalizer[lang](alias(aliases, original.Name))
+			// Name shouldn't start with a digit. It will make the generated code invalid.
+			if len(normalizedName) > 0 && unicode.IsDigit(rune(normalizedName[0])) {
+				normalizedName = fmt.Sprintf("E%s", normalizedName)
+				normalizedName = abi.ResolveNameConflict(normalizedName, func(name string) bool {
+					_, ok := eventIdentifiers[name]
+					return ok
+				})
+			}
 			if eventIdentifiers[normalizedName] {
 				return "", fmt.Errorf("duplicated identifier \"%s\"(normalized \"%s\"), use --alias for renaming", original.Name, normalizedName)
 			}

accounts/abi/bind/bind_test.go

@@ -2038,6 +2038,29 @@ var bindTests = []struct {
 				t.Errorf("error deploying the contract: %v", err)
 			}
 		`,
+	}, {
+		name: "NumericMethodName",
+		contract: `
+		// SPDX-License-Identifier: GPL-3.0
+		pragma solidity >=0.4.22 <0.9.0;
+
+		contract NumericMethodName {
+			event _1TestEvent(address _param);
+			function _1test() public pure {}
+			function __1test() public pure {}
+			function __2test() public pure {}
+		}
+		`,
+		bytecode: []string{"0x6080604052348015600f57600080fd5b5060958061001e6000396000f3fe6080604052348015600f57600080fd5b5060043610603c5760003560e01c80639d993132146041578063d02767c7146049578063ffa02795146051575b600080fd5b60476059565b005b604f605b565b005b6057605d565b005b565b565b56fea26469706673582212200382ca602dff96a7e2ba54657985e2b4ac423a56abe4a1f0667bc635c4d4371f64736f6c63430008110033"},
+		abi:      []string{`[{"anonymous":false,"inputs":[{"indexed":false,"internalType":"address","name":"_param","type":"address"}],"name":"_1TestEvent","type":"event"},{"inputs":[],"name":"_1test","outputs":[],"stateMutability":"pure","type":"function"},{"inputs":[],"name":"__1test","outputs":[],"stateMutability":"pure","type":"function"},{"inputs":[],"name":"__2test","outputs":[],"stateMutability":"pure","type":"function"}]`},
+		imports: `
+			"github.com/ethereum/go-ethereum/common"
+		`,
+		tester: `
+			if b, err := NewNumericMethodName(common.Address{}, nil); b == nil || err != nil {
+				t.Fatalf("combined binding (%v) nil or error (%v) not nil", b, nil)
+			}
+`,
 	},
 }