Merge pull request #4671 from ethereum/mappingTupleAssignment

Disallow assignments to mappings within tuple assignments; allow for local variables.

test/libsolidity/syntaxTests/nameAndTypeResolution/016_assignment_to_mapping.sol

@@ -1,12 +0,0 @@
-contract test {
-    struct str {
-        mapping(uint=>uint) map;
-    }
-    str data;
-    function fun() public {
-        mapping(uint=>uint) storage a = data.map;
-        data.map = a;
-    }
-}
-// ----
-// TypeError: (172-184): Mappings cannot be assigned to.

test/libsolidity/syntaxTests/types/mapping/assignment_local.sol

@@ -0,0 +1,11 @@
+contract test {
+    mapping(uint=>uint) map;
+    function fun() public view {
+        mapping(uint=>uint) storage a = map;
+        mapping(uint=>uint) storage b = map;
+        b = a;
+        (b) = a;
+        (b, b) = (a, a);
+    }
+}
+// ----

test/libsolidity/syntaxTests/types/mapping/assignment_state_variable.sol

@@ -0,0 +1,14 @@
+contract test {
+    mapping(uint=>uint) map;
+    function fun() public {
+        mapping(uint=>uint) storage a = map;
+        map = a;
+        (map) = a;
+        (map, map) = (a, a);
+    }
+}
+// ----
+// TypeError: (126-129): Mappings cannot be assigned to.
+// TypeError: (144-147): Mappings cannot be assigned to.
+// TypeError: (163-166): Mappings cannot be assigned to.
+// TypeError: (168-171): Mappings cannot be assigned to.

test/libsolidity/syntaxTests/types/mapping/assignment_struct.sol

@@ -0,0 +1,17 @@
+contract test {
+    struct str {
+        mapping(uint=>uint) map;
+    }
+    str data;
+    function fun() public {
+        mapping(uint=>uint) storage a = data.map;
+        data.map = a;
+        (data.map) = a;
+        (data.map, data.map) = (a, a);
+    }
+}
+// ----
+// TypeError: (172-180): Mappings cannot be assigned to.
+// TypeError: (195-203): Mappings cannot be assigned to.
+// TypeError: (219-227): Mappings cannot be assigned to.
+// TypeError: (229-237): Mappings cannot be assigned to.

test/libsolidity/syntaxTests/types/mapping/mapping_return_external.sol

@@ -0,0 +1,7 @@
+contract C {
+    function f() external pure returns (mapping(uint=>uint) storage m) {
+    }
+}
+// ----
+// TypeError: (53-82): Type is required to live outside storage.
+// TypeError: (53-82): Internal or recursive type is not allowed for public or external functions.

test/libsolidity/syntaxTests/types/mapping/mapping_return_internal.sol

@@ -0,0 +1,21 @@
+// This should be allowed in a future release.
+contract C {
+    mapping(uint=>uint) m;
+    function f() internal view returns (mapping(uint=>uint) storage) {
+        return m;
+    }
+    function g() private view returns (mapping(uint=>uint) storage) {
+        return m;
+    }
+    function h() internal view returns (mapping(uint=>uint) storage r) {
+        r = m;
+    }
+    function i() private view returns (mapping(uint=>uint) storage r) {
+        (r,r) = (m,m);
+    }
+}
+// ----
+// TypeError: (127-146): Type is required to live outside storage.
+// TypeError: (221-240): Type is required to live outside storage.
+// TypeError: (316-345): Type is required to live outside storage.
+// TypeError: (409-438): Type is required to live outside storage.

test/libsolidity/syntaxTests/types/mapping/mapping_return_public.sol

@@ -0,0 +1,7 @@
+contract C {
+    function f() public pure returns (mapping(uint=>uint) storage m) {
+    }
+}
+// ----
+// TypeError: (51-80): Type is required to live outside storage.
+// TypeError: (51-80): Internal or recursive type is not allowed for public or external functions.