From 4d791b2679283d173896d118730c8b598bd2b7f6 Mon Sep 17 00:00:00 2001
From: Alex Beregszaszi <alex@rtfs.hu>
Date: Fri, 13 Dec 2019 14:46:28 +0000
Subject: [PATCH] Issue warning if codesize exceeds EIP-170 limits

---
 Changelog.md                                      |  2 +-
 libsolidity/interface/CompilerStack.cpp           | 15 +++++++++++++++
 .../syntaxTests/bytecode_too_large.sol            | 10 ++++++++++
 3 files changed, 26 insertions(+), 1 deletion(-)
 create mode 100644 test/libsolidity/syntaxTests/bytecode_too_large.sol

diff --git a/Changelog.md b/Changelog.md
index 817ee9180..9b795d50d 100644
--- a/Changelog.md
+++ b/Changelog.md
@@ -4,7 +4,7 @@ Language Features:
 
 
 Compiler Features:
-
+ * General: Raise warning if runtime bytecode exceeds 24576 bytes (a limit introduced in Spurious Dragon).
 
 Bugfixes:
 
diff --git a/libsolidity/interface/CompilerStack.cpp b/libsolidity/interface/CompilerStack.cpp
index 73824297e..396b7d2f8 100644
--- a/libsolidity/interface/CompilerStack.cpp
+++ b/libsolidity/interface/CompilerStack.cpp
@@ -1046,6 +1046,21 @@ void CompilerStack::compileContract(
 		solAssert(false, "Assembly exception for deployed bytecode");
 	}
 
+	// Throw a warning if EIP-170 limits are exceeded:
+	//   If contract creation initialization returns data with length of more than 0x6000 (214 + 213) bytes,
+	//   contract creation fails with an out of gas error.
+	if (
+		m_evmVersion >= langutil::EVMVersion::spuriousDragon() &&
+		compiledContract.runtimeObject.bytecode.size() > 0x6000
+	)
+		m_errorReporter.warning(
+			_contract.location(),
+			"Contract code size exceeds 24576 bytes (a limit introduced in Spurious Dragon). "
+			"This contract may not be deployable on mainnet. "
+			"Consider enabling the optimizer (with a low \"runs\" value!), "
+			"turning off revert strings, or using libraries."
+		);
+
 	_otherCompilers[compiledContract.contract] = compiler;
 }
 
diff --git a/test/libsolidity/syntaxTests/bytecode_too_large.sol b/test/libsolidity/syntaxTests/bytecode_too_large.sol
new file mode 100644
index 000000000..ea8831e13
--- /dev/null
+++ b/test/libsolidity/syntaxTests/bytecode_too_large.sol
@@ -0,0 +1,10 @@
+contract test {
+    function f() public pure returns (string memory ret) {
+        // 27000 bytes long data
+        ret = ".......................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................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+    }
+}
+// ====
+// EVMVersion: >=spuriousDragon
+// ----
+// Warning: (0-27133): Contract code size exceeds 24576 bytes (a limit introduced in Spurious Dragon). This contract may not be deployable on mainnet. Consider enabling the optimizer (with a low "runs" value!), turning off revert strings, or using libraries.