From 7a51acc5fe3458d6c76c81ae409761dfd4be9be5 Mon Sep 17 00:00:00 2001
From: Marenz <github@supradigital.org>
Date: Tue, 21 Sep 2021 18:02:20 +0200
Subject: [PATCH] Correct wrong error message referencing `.slot` and `.offset`
 when `.length` was used

---
 Changelog.md                                           |  1 +
 libsolidity/analysis/TypeChecker.cpp                   |  4 ++--
 .../inlineAssembly/invalid/constant_length_access.sol  | 10 ++++++++++
 3 files changed, 13 insertions(+), 2 deletions(-)
 create mode 100644 test/libsolidity/syntaxTests/inlineAssembly/invalid/constant_length_access.sol

diff --git a/Changelog.md b/Changelog.md
index 2d0a1e484..eacd9777b 100644
--- a/Changelog.md
+++ b/Changelog.md
@@ -29,6 +29,7 @@ Bugfixes:
  * SMTChecker: Fix false positive in external calls from constructors.
  * SMTChecker: Fix internal error on some multi-source uses of ``abi.*``, cryptographic functions and constants.
  * Standard JSON: Fix non-fatal errors in Yul mode being discarded if followed by a fatal error.
+ * Type Checker: Correct wrong error message in inline assembly complaining about ``.slot`` or ``.offset` not valid when actually ``.length`` was used.
  * Type Checker: Disallow modifier declarations and definitions in interfaces.
  * Yul Optimizer: Fix a crash in LoadResolver, when ``keccak256`` has particular non-identifier arguments.
 
diff --git a/libsolidity/analysis/TypeChecker.cpp b/libsolidity/analysis/TypeChecker.cpp
index afcf92525..c9772f1c8 100644
--- a/libsolidity/analysis/TypeChecker.cpp
+++ b/libsolidity/analysis/TypeChecker.cpp
@@ -799,7 +799,7 @@ bool TypeChecker::visit(InlineAssembly const& _inlineAssembly)
 					m_errorReporter.typeError(6252_error, _identifier.debugData->location, "Constant variables cannot be assigned to.");
 					return false;
 				}
-				else if (!identifierInfo.suffix.empty())
+				else if (identifierInfo.suffix == "slot" || identifierInfo.suffix == "offset")
 				{
 					m_errorReporter.typeError(6617_error, _identifier.debugData->location, "The suffixes .offset and .slot can only be used on non-constant storage variables.");
 					return false;
@@ -829,7 +829,7 @@ bool TypeChecker::visit(InlineAssembly const& _inlineAssembly)
 			{
 				string const& suffix = identifierInfo.suffix;
 				solAssert((set<string>{"offset", "slot", "length"}).count(suffix), "");
-				if (var->isStateVariable() || var->type()->dataStoredIn(DataLocation::Storage))
+				if (!var->isConstant() && (var->isStateVariable() || var->type()->dataStoredIn(DataLocation::Storage)))
 				{
 					if (suffix != "slot" && suffix != "offset")
 					{
diff --git a/test/libsolidity/syntaxTests/inlineAssembly/invalid/constant_length_access.sol b/test/libsolidity/syntaxTests/inlineAssembly/invalid/constant_length_access.sol
new file mode 100644
index 000000000..eda71f955
--- /dev/null
+++ b/test/libsolidity/syntaxTests/inlineAssembly/invalid/constant_length_access.sol
@@ -0,0 +1,10 @@
+contract Test {
+	uint constant x = 2;
+	function f() public pure {
+		assembly {
+			let y := x.length
+		}
+	}
+}
+// ----
+// TypeError 3622: (91-99): The suffix ".length" is not supported by this variable or type.