From 3eaa37030a10c74a0d5d046f165ce84864dec068 Mon Sep 17 00:00:00 2001
From: chriseth <chris@ethereum.org>
Date: Tue, 8 Jun 2021 12:43:43 +0200
Subject: [PATCH] Fix infinite recursion in function call graph generator due
 to recursive constant references.

---
 Changelog.md                                       |  1 +
 libsolidity/interface/CompilerStack.cpp            | 14 +++++++-------
 .../syntaxTests/constants/cyclic_dependency_5.sol  |  8 ++++++++
 3 files changed, 16 insertions(+), 7 deletions(-)
 create mode 100644 test/libsolidity/syntaxTests/constants/cyclic_dependency_5.sol

diff --git a/Changelog.md b/Changelog.md
index 354eb6414..0bedeb7d6 100644
--- a/Changelog.md
+++ b/Changelog.md
@@ -20,6 +20,7 @@ Bugfixes:
  * Code Generator: Fix internal error when super would have to skip an unimplemented function in the virtual resolution order.
  * Control Flow Graph: Take internal calls to functions that always revert into account for reporting unused or unassigned variables.
  * Control Flow Graph: Assume unimplemented modifiers use a placeholder.
+ * Function Call Graph: Fix internal error connected with circular constant references.
  * Natspec: Allow multiple ``@return`` tags on public state variable documentation.
  * SMTChecker: Fix internal error on struct constructor with fixed bytes member initialized with string literal.
  * SMTChecker: Fix internal error on external calls from the constructor.
diff --git a/libsolidity/interface/CompilerStack.cpp b/libsolidity/interface/CompilerStack.cpp
index 00919ddba..35e497f9a 100644
--- a/libsolidity/interface/CompilerStack.cpp
+++ b/libsolidity/interface/CompilerStack.cpp
@@ -480,13 +480,6 @@ bool CompilerStack::analyze()
 			if (source->ast && !typeChecker.checkTypeRequirements(*source->ast))
 				noErrors = false;
 
-		// Create & assign callgraphs and check for contract dependency cycles
-		if (noErrors)
-		{
-			createAndAssignCallGraphs();
-			findAndReportCyclicContractDependencies();
-		}
-
 		if (noErrors)
 		{
 			// Checks that can only be done when all types of all AST nodes are known.
@@ -498,6 +491,13 @@ bool CompilerStack::analyze()
 				noErrors = false;
 		}
 
+		// Create & assign callgraphs and check for contract dependency cycles
+		if (noErrors)
+		{
+			createAndAssignCallGraphs();
+			findAndReportCyclicContractDependencies();
+		}
+
 		if (noErrors)
 			for (Source const* source: m_sourceOrder)
 				if (source->ast && !PostTypeContractLevelChecker{m_errorReporter}.check(*source->ast))
diff --git a/test/libsolidity/syntaxTests/constants/cyclic_dependency_5.sol b/test/libsolidity/syntaxTests/constants/cyclic_dependency_5.sol
new file mode 100644
index 000000000..b8a5b49ae
--- /dev/null
+++ b/test/libsolidity/syntaxTests/constants/cyclic_dependency_5.sol
@@ -0,0 +1,8 @@
+contract C {
+  uint constant a = uint(keccak256(abi.encode(d)));
+  uint c = uint(keccak256(abi.encode(d)));
+  uint constant d = a;
+}
+// ----
+// TypeError 6161: (15-63): The value of the constant a has a cyclic dependency via d.
+// TypeError 6161: (110-129): The value of the constant d has a cyclic dependency via a.