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Merge pull request #12921 from ethereum/add_event_and_error_selector_fields_on_the_line_of_function_selector_field
Adding event and error selector fields
2 parents 2bbc9a1 + d4c06d2 commit f0e4392

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lines changed

‎Changelog.md

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### 0.8.15 (unreleased)
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Language Features:
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* General: Add `E.selector` for a non-anonymous event `E` to access the 32-byte selector topic.
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* General: Errors and Events allow qualified access from other contracts.
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Compiler Features:

‎docs/contracts/events.rst

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@@ -73,6 +73,16 @@ four indexed arguments rather than three.
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In particular, it is possible to "fake" the signature of another event
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using an anonymous event.
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Members of Events
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=================
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- ``event.selector``: For non-anonymous events, this is a ``bytes32`` value
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containing the ``keccak256`` hash of the event signature, as used in the default topic.
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Example
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=======
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.. code-block:: solidity
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// SPDX-License-Identifier: GPL-3.0

‎libsolidity/ast/AST.h

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@@ -1216,7 +1216,7 @@ class EventDefinition: public CallableDeclaration, public StructurallyDocumented
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FunctionTypePointer functionType(bool /*_internal*/) const override;
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bool isVisibleInDerivedContracts() const override { return true; }
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bool isVisibleViaContractTypeAccess() const override { return false; /* TODO */ }
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bool isVisibleViaContractTypeAccess() const override { return true; }
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EventDefinitionAnnotation& annotation() const override;
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‎libsolidity/ast/Types.cpp

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@@ -3335,6 +3335,12 @@ MemberList::MemberMap FunctionType::nativeMembers(ASTNode const* _scope) const
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}
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case Kind::Error:
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return {{"selector", TypeProvider::fixedBytes(4)}};
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case Kind::Event:
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{
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if (!(dynamic_cast<EventDefinition const&>(declaration()).isAnonymous()))
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return {{"selector", TypeProvider::fixedBytes(32)}};
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return MemberList::MemberMap();
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}
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default:
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return MemberList::MemberMap();
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}

‎libsolidity/codegen/ExpressionCompiler.cpp

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@@ -1602,9 +1602,14 @@ bool ExpressionCompiler::visit(MemberAccess const& _memberAccess)
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{
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if (functionType->hasDeclaration())
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{
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m_context << functionType->externalIdentifier();
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/// need to store it as bytes4
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utils().leftShiftNumberOnStack(224);
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if (functionType->kind() == FunctionType::Kind::Event)
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m_context << u256(h256::Arith(util::keccak256(functionType->externalSignature())));
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else
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{
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m_context << functionType->externalIdentifier();
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/// need to store it as bytes4
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utils().leftShiftNumberOnStack(224);
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}
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return false;
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}
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else if (auto const* expr = dynamic_cast<MemberAccess const*>(&_memberAccess.expression()))
@@ -1775,9 +1780,13 @@ bool ExpressionCompiler::visit(MemberAccess const& _memberAccess)
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if (member == "selector")
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{
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auto const& functionType = dynamic_cast<FunctionType const&>(*_memberAccess.expression().annotation().type);
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// all events should have already been caught by this stage
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solAssert(!(functionType.kind() == FunctionType::Kind::Event));
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if (functionType.kind() == FunctionType::Kind::External)
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CompilerUtils(m_context).popStackSlots(functionType.sizeOnStack() - 2);
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m_context << Instruction::SWAP1 << Instruction::POP;
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/// need to store it as bytes4
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utils().leftShiftNumberOnStack(224);
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}

‎libsolidity/codegen/ir/IRGeneratorForStatements.cpp

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@@ -1785,7 +1785,20 @@ void IRGeneratorForStatements::endVisit(MemberAccess const& _memberAccess)
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functionType.declaration().isPartOfExternalInterface(),
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""
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);
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define(IRVariable{_memberAccess}) << formatNumber(functionType.externalIdentifier() << 224) << "\n";
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define(IRVariable{_memberAccess}) << formatNumber(
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util::selectorFromSignature(functionType.externalSignature())
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) << "\n";
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}
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else if (functionType.kind() == FunctionType::Kind::Event)
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{
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solAssert(functionType.hasDeclaration());
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solAssert(functionType.kind() == FunctionType::Kind::Event);
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solAssert(
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!(dynamic_cast<EventDefinition const&>(functionType.declaration()).isAnonymous())
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);
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define(IRVariable{_memberAccess}) << formatNumber(
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u256(h256::Arith(util::keccak256(functionType.externalSignature())))
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) << "\n";
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}
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else
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solAssert(false, "Invalid use of .selector: " + functionType.toString(false));

‎test/libsolidity/semanticTests/error/error_selector.sol

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library L {
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error E();
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}
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library S {
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error E(uint);
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}
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library T {
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error E();
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}
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error E();
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interface I {
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error E();
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function f() external pure;
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}
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contract D {
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error F();
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}
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contract C is D {
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function test1() public pure returns (bytes4, bytes4, bytes4, bytes4) {
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assert(L.E.selector == T.E.selector);
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assert(L.E.selector != S.E.selector);
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assert(E.selector == L.E.selector);
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assert(I.E.selector == L.E.selector);
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return (L.E.selector, S.E.selector, E.selector, I.E.selector);
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}
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bytes4 s1 = L.E.selector;
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bytes4 s2 = S.E.selector;
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bytes4 s3 = T.E.selector;
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bytes4 s4 = I.E.selector;
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function test2() external returns (bytes4, bytes4, bytes4, bytes4) {
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return (s1, s2, s3, s4);
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}
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function test3() external returns (bytes4) {
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return (F.selector);
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}
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}
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// ====
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// compileViaYul: also
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// ----
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// test1() -> 0x92bbf6e800000000000000000000000000000000000000000000000000000000, 0x2ff06700000000000000000000000000000000000000000000000000000000, 0x92bbf6e800000000000000000000000000000000000000000000000000000000, 0x92bbf6e800000000000000000000000000000000000000000000000000000000
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// test2() -> 0x92bbf6e800000000000000000000000000000000000000000000000000000000, 0x2ff06700000000000000000000000000000000000000000000000000000000, 0x92bbf6e800000000000000000000000000000000000000000000000000000000, 0x92bbf6e800000000000000000000000000000000000000000000000000000000
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// test3() -> 0x28811f5900000000000000000000000000000000000000000000000000000000

‎test/libsolidity/semanticTests/events/event_selector.sol

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library L {
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event E();
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}
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library S {
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event E(uint);
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}
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library T {
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event E();
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}
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interface I {
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event E();
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}
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contract D {
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event F();
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}
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contract C is D {
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function test1() external pure returns (bytes32, bytes32, bytes32) {
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assert(L.E.selector == T.E.selector);
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assert(I.E.selector == L.E.selector);
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assert(L.E.selector != S.E.selector);
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assert(T.E.selector != S.E.selector);
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assert(I.E.selector != S.E.selector);
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return (L.E.selector, S.E.selector, I.E.selector);
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}
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bytes32 s1 = L.E.selector;
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bytes32 s2 = S.E.selector;
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bytes32 s3 = T.E.selector;
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bytes32 s4 = I.E.selector;
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function test2() external returns (bytes32, bytes32, bytes32, bytes32) {
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return (s1, s2, s3, s4);
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}
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function test3() external returns (bytes32) {
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return (F.selector);
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}
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}
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// ====
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// compileViaYul: also
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// ----
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// test1() -> 0x92bbf6e823a631f3c8e09b1c8df90f378fb56f7fbc9701827e1ff8aad7f6a028, 0x2ff0672f372fbe844b353429d4510ea5e43683af134c54f75f789ff57bc0c0, 0x92bbf6e823a631f3c8e09b1c8df90f378fb56f7fbc9701827e1ff8aad7f6a028
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// test2() -> 0x92bbf6e823a631f3c8e09b1c8df90f378fb56f7fbc9701827e1ff8aad7f6a028, 0x2ff0672f372fbe844b353429d4510ea5e43683af134c54f75f789ff57bc0c0, 0x92bbf6e823a631f3c8e09b1c8df90f378fb56f7fbc9701827e1ff8aad7f6a028, 0x92bbf6e823a631f3c8e09b1c8df90f378fb56f7fbc9701827e1ff8aad7f6a028
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// test3() -> 0x28811f5935c16a099486acb976b3a6b4942950a1425a74e9eb3e9b7f7135e12a

‎test/libsolidity/semanticTests/events/simple.sol

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contract C {
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event E();
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}
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contract Test {
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event E(uint256, uint256);
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function f() public {
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emit C.E();
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emit E(1,2);
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}
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}
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// ====
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// compileViaYul: also
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// ----
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// f() ->
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// ~ emit E()
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// ~ emit E(uint256,uint256): 0x01, 0x02

‎test/libsolidity/syntaxTests/errors/error_selector_syntax.sol

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library L {
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error E();
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}
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library S {
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error E(uint);
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}
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library T {
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error E();
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}
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error E();
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interface I {
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error E();
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function f() external pure;
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}
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contract D {
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error F();
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}
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contract C is D {
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function test1() public pure returns (bytes4, bytes4, bytes4, bytes4) {
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assert(L.E.selector == T.E.selector);
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assert(L.E.selector != S.E.selector);
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assert(E.selector == L.E.selector);
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assert(I.E.selector == L.E.selector);
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return (L.E.selector, S.E.selector, E.selector, I.E.selector);
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}
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bytes4 s1 = L.E.selector;
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bytes4 s2 = S.E.selector;
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bytes4 s3 = T.E.selector;
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bytes4 s4 = I.E.selector;
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function test2() view external returns (bytes4, bytes4, bytes4, bytes4) {
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return (s1, s2, s3, s4);
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}
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function test3() pure external returns (bytes4) {
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return (F.selector);
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}
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}
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// ----
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// Warning 2519: (16-26): This declaration shadows an existing declaration.
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// Warning 2519: (45-59): This declaration shadows an existing declaration.
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// Warning 2519: (78-88): This declaration shadows an existing declaration.
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// Warning 2519: (122-132): This declaration shadows an existing declaration.

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