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Change effect of assert to invalid opcode. #1702

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Mar 3, 2017
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Change effect of assert to invalid opcode. #1702

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811bb77
Change effect of assert to invalid opcode.
chriseth Feb 16, 2017
4b1e811
Remove assert for now.
chriseth Feb 23, 2017
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3 changes: 1 addition & 2 deletions docs/control-structures.rst
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Expand Up @@ -398,10 +398,9 @@ Currently, Solidity automatically generates a runtime exception in the following

While a user-provided exception is generated in the following situations:
#. Calling ``throw``.
#. The condition of ``assert(condition)`` is not met.

Internally, Solidity performs a revert operation (instruction ``0xfd``) when a user-provided exception is thrown. In contrast, it performs an invalid operation
(instruction ``0xfe``) if a runtime exception is encountered. In both cases, this causes
the EVM to revert all changes made to the state. The reason for this is that there is no safe way to continue execution, because an expected effect
did not occur. Because we want to retain the atomicity of transactions, the safest thing to do is to revert all changes and make the whole transaction
(or at least call) without effect.
(or at least call) without effect.
3 changes: 1 addition & 2 deletions docs/miscellaneous.rst
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Expand Up @@ -435,7 +435,7 @@ The following is the order of precedence for operators, listed in order of evalu
| *16* | Comma operator | ``,`` |
+------------+-------------------------------------+--------------------------------------------+

.. index:: block, coinbase, difficulty, number, block;number, timestamp, block;timestamp, msg, data, gas, sender, value, now, gas price, origin, assert, revert, keccak256, ripemd160, sha256, ecrecover, addmod, mulmod, cryptography, this, super, selfdestruct, balance, send
.. index:: block, coinbase, difficulty, number, block;number, timestamp, block;timestamp, msg, data, gas, sender, value, now, gas price, origin, revert, keccak256, ripemd160, sha256, ecrecover, addmod, mulmod, cryptography, this, super, selfdestruct, balance, send

Global Variables
================
Expand All @@ -461,7 +461,6 @@ Global Variables
- ``ecrecover(bytes32 hash, uint8 v, bytes32 r, bytes32 s) returns (address)``: recover address associated with the public key from elliptic curve signature, return zero on error
- ``addmod(uint x, uint y, uint k) returns (uint)``: compute ``(x + y) % k`` where the addition is performed with arbitrary precision and does not wrap around at ``2**256``
- ``mulmod(uint x, uint y, uint k) returns (uint)``: compute ``(x * y) % k`` where the multiplication is performed with arbitrary precision and does not wrap around at ``2**256``
- ``assert(bool condition)``: throws if the condition is false
- ``this`` (current contract's type): the current contract, explicitly convertible to ``address``
- ``super``: the contract one level higher in the inheritance hierarchy
- ``selfdestruct(address recipient)``: destroy the current contract, sending its funds to the given address
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5 changes: 3 additions & 2 deletions libsolidity/analysis/GlobalContext.cpp
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Expand Up @@ -66,8 +66,9 @@ m_magicVariables(vector<shared_ptr<MagicVariableDeclaration const>>{make_shared<
make_shared<FunctionType>(strings{"bytes32", "uint8", "bytes32", "bytes32"}, strings{"address"}, FunctionType::Location::ECRecover)),
make_shared<MagicVariableDeclaration>("ripemd160",
make_shared<FunctionType>(strings(), strings{"bytes20"}, FunctionType::Location::RIPEMD160, true)),
make_shared<MagicVariableDeclaration>("assert",
make_shared<FunctionType>(strings{"bool"}, strings{}, FunctionType::Location::Assert)),
// Disabled until decision about semantics of assert is made.
// make_shared<MagicVariableDeclaration>("assert",
// make_shared<FunctionType>(strings{"bool"}, strings{}, FunctionType::Location::Assert)),
make_shared<MagicVariableDeclaration>("revert",
make_shared<FunctionType>(strings(), strings(), FunctionType::Location::Revert))})
{
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5 changes: 2 additions & 3 deletions libsolidity/codegen/ExpressionCompiler.cpp
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Expand Up @@ -875,9 +875,8 @@ bool ExpressionCompiler::visit(FunctionCall const& _functionCall)
// jump if condition was met
m_context << Instruction::ISZERO << Instruction::ISZERO;
auto success = m_context.appendConditionalJump();
// condition was not met, abort
m_context << u256(0) << u256(0);
m_context << Instruction::REVERT;
// condition was not met, flag an error
m_context << Instruction::INVALID;
// the success branch
m_context << success;
break;
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36 changes: 18 additions & 18 deletions test/libsolidity/SolidityEndToEndTest.cpp
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Expand Up @@ -9083,24 +9083,24 @@ BOOST_AUTO_TEST_CASE(invalid_instruction)
BOOST_CHECK(callContractFunction("f()") == encodeArgs());
}

BOOST_AUTO_TEST_CASE(assert)
{
char const* sourceCode = R"(
contract C {
function f() {
assert(false);
}
function g(bool val) returns (bool) {
assert(val == true);
return true;
}
}
)";
compileAndRun(sourceCode, 0, "C");
BOOST_CHECK(callContractFunction("f()") == encodeArgs());
BOOST_CHECK(callContractFunction("g(bool)", false) == encodeArgs());
BOOST_CHECK(callContractFunction("g(bool)", true) == encodeArgs(true));
}
//BOOST_AUTO_TEST_CASE(assert)
//{
// char const* sourceCode = R"(
// contract C {
// function f() {
// assert(false);
// }
// function g(bool val) returns (bool) {
// assert(val == true);
// return true;
// }
// }
// )";
// compileAndRun(sourceCode, 0, "C");
// BOOST_CHECK(callContractFunction("f()") == encodeArgs());
// BOOST_CHECK(callContractFunction("g(bool)", false) == encodeArgs());
// BOOST_CHECK(callContractFunction("g(bool)", true) == encodeArgs(true));
//}

BOOST_AUTO_TEST_CASE(revert)
{
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