Add control flow analyzer and test for uninitialized storage returns.

test/libsolidity/syntaxTests/controlFlow/storageReturn/assembly_fine.sol

@@ -0,0 +1,26 @@
+contract C {
+    struct S { bool f; }
+    S s;
+    function f() internal returns (S storage c) {
+        assembly {
+            sstore(c_slot, sload(s_slot))
+        }
+    }
+    function g(bool flag) internal returns (S storage c) {
+        // control flow in assembly will not be analyzed for now,
+        // so this will not issue a warning
+        assembly {
+            if flag {
+                sstore(c_slot, sload(s_slot))
+            }
+        }
+    }
+    function h() internal returns (S storage c) {
+        // any reference from assembly will be sufficient for now,
+        // so this will not issue a warning
+        assembly {
+            sstore(s_slot, sload(c_slot))
+        }
+    }
+}
+// ----

test/libsolidity/syntaxTests/controlFlow/storageReturn/assembly_warn.sol

@@ -0,0 +1,10 @@
+contract C {
+    struct S { bool f; }
+    S s;
+    function f() internal pure returns (S storage) {
+        assembly {
+        }
+    }
+}
+// ----
+// Warning: (87-88): This variable is of storage pointer type and might be returned without assignment. This can cause storage corruption. Assign the variable (potentially from itself) to remove this warning.

test/libsolidity/syntaxTests/controlFlow/storageReturn/dowhile_fine.sol

@@ -0,0 +1,36 @@
+contract C {
+    struct S { bool f; }
+    S s;
+    function f() internal view returns (S storage c) {
+        do {} while((c = s).f);
+    }
+    function g() internal view returns (S storage c) {
+        do { c = s; } while(false);
+    }
+    function h() internal view returns (S storage c) {
+        c = s;
+        do {} while(false);
+    }
+    function i() internal view returns (S storage c) {
+        do {} while(false);
+        c = s;
+    }
+    function j() internal view returns (S storage c) {
+        do {
+            c = s;
+            break;
+        } while(false);
+    }
+    function k() internal view returns (S storage c) {
+        do {
+            if (s.f) {
+                continue;
+                break;
+            }
+            else {
+                c = s;
+            }
+        } while(false);
+    }
+}
+// ----

test/libsolidity/syntaxTests/controlFlow/storageReturn/dowhile_warn.sol

@@ -0,0 +1,35 @@
+contract C {
+    struct S { bool f; }
+    S s;
+    function f() internal view returns (S storage c) {
+        do {
+            break;
+            c = s;
+        } while(false);
+    }
+    function g() internal view returns (S storage c) {
+        do {
+            if (s.f) {
+                continue;
+                c = s;
+            }
+            else {
+            }
+        } while(false);
+    }
+    function h() internal view returns (S storage c) {
+        do {
+            if (s.f) {
+                break;
+                continue;
+            }
+            else {
+                c = s;
+            }
+        } while(false);
+    }
+}
+// ----
+// Warning: (87-98): This variable is of storage pointer type and might be returned without assignment. This can cause storage corruption. Assign the variable (potentially from itself) to remove this warning.
+// Warning: (223-234): This variable is of storage pointer type and might be returned without assignment. This can cause storage corruption. Assign the variable (potentially from itself) to remove this warning.
+// Warning: (440-451): This variable is of storage pointer type and might be returned without assignment. This can cause storage corruption. Assign the variable (potentially from itself) to remove this warning.

test/libsolidity/syntaxTests/controlFlow/storageReturn/emptyReturn_fine.sol

@@ -0,0 +1,6 @@
+contract C {
+    struct S { bool f; }
+    S s;
+    function f() internal view returns (S storage c, S storage d) { c = s; d = s; return; }
+}
+// ----

test/libsolidity/syntaxTests/controlFlow/storageReturn/emptyReturn_warn.sol

@@ -0,0 +1,15 @@
+contract C {
+    struct S { bool f; }
+    S s;
+    function f() internal pure returns (S storage) { return; }
+    function g() internal view returns (S storage c, S storage) { c = s; return; }
+    function h() internal view returns (S storage, S storage d) { d = s; return; }
+    function i() internal pure returns (S storage, S storage) { return; }
+    function j() internal view returns (S storage, S storage) { return (s,s); }
+}
+// ----
+// Warning: (87-88): This variable is of storage pointer type and might be returned without assignment. This can cause storage corruption. Assign the variable (potentially from itself) to remove this warning.
+// Warning: (163-164): This variable is of storage pointer type and might be returned without assignment. This can cause storage corruption. Assign the variable (potentially from itself) to remove this warning.
+// Warning: (233-234): This variable is of storage pointer type and might be returned without assignment. This can cause storage corruption. Assign the variable (potentially from itself) to remove this warning.
+// Warning: (316-317): This variable is of storage pointer type and might be returned without assignment. This can cause storage corruption. Assign the variable (potentially from itself) to remove this warning.
+// Warning: (327-328): This variable is of storage pointer type and might be returned without assignment. This can cause storage corruption. Assign the variable (potentially from itself) to remove this warning.

test/libsolidity/syntaxTests/controlFlow/storageReturn/for_fine.sol

@@ -0,0 +1,13 @@
+contract C {
+    struct S { bool f; }
+    S s;
+    function f() internal view returns (S storage c) {
+        for(c = s;;) {
+        }
+    }
+    function g() internal view returns (S storage c) {
+        for(; (c = s).f;) {
+        }
+    }
+}
+// ----

test/libsolidity/syntaxTests/controlFlow/storageReturn/for_warn.sol

@@ -0,0 +1,16 @@
+contract C {
+    struct S { bool f; }
+    S s;
+    function f() internal view returns (S storage c) {
+        for(;; c = s) {
+        }
+    }
+    function g() internal view returns (S storage c) {
+        for(;;) {
+            c = s;
+        }
+    }
+}
+// ----
+// Warning: (87-98): This variable is of storage pointer type and might be returned without assignment. This can cause storage corruption. Assign the variable (potentially from itself) to remove this warning.
+// Warning: (182-193): This variable is of storage pointer type and might be returned without assignment. This can cause storage corruption. Assign the variable (potentially from itself) to remove this warning.

test/libsolidity/syntaxTests/controlFlow/storageReturn/if_fine.sol

@@ -0,0 +1,29 @@
+contract C {
+    struct S { bool f; }
+    S s;
+    function f(bool flag) internal view returns (S storage c) {
+        if (flag) c = s;
+        else c = s;
+    }
+    function g(bool flag) internal view returns (S storage c) {
+        if (flag) c = s;
+        else { c = s; }
+    }
+    function h(bool flag) internal view returns (S storage c) {
+        if (flag) c = s;
+        else
+        {
+            if (!flag) c = s;
+            else c = s;
+        }
+    }
+    function i() internal view returns (S storage c) {
+        if ((c = s).f) {
+        }
+    }
+    function j() internal view returns (S storage c) {
+        if ((c = s).f && !(c = s).f) {
+        }
+    }
+}
+// ----

test/libsolidity/syntaxTests/controlFlow/storageReturn/if_warn.sol

@@ -0,0 +1,18 @@
+contract C {
+    struct S { bool f; }
+    S s;
+    function f(bool flag) internal view returns (S storage c) {
+        if (flag) c = s;
+    }
+    function g(bool flag) internal returns (S storage c) {
+        if (flag) c = s;
+        else
+        {
+            if (!flag) c = s;
+            else s.f = true;
+        }
+    }
+}
+// ----
+// Warning: (96-107): This variable is of storage pointer type and might be returned without assignment. This can cause storage corruption. Assign the variable (potentially from itself) to remove this warning.
+// Warning: (186-197): This variable is of storage pointer type and might be returned without assignment. This can cause storage corruption. Assign the variable (potentially from itself) to remove this warning.

test/libsolidity/syntaxTests/controlFlow/storageReturn/modifier_fine.sol

@@ -0,0 +1,20 @@
+contract C {
+    modifier revertIfNoReturn() {
+        _;
+        revert();
+    }
+    modifier ifFlag(bool flag) {
+        if (flag)
+            _;
+    }
+    struct S { uint a; }
+    S s;
+    function f(bool flag) revertIfNoReturn() internal view returns(S storage) {
+        if (flag) return s;
+    }
+    function g(bool flag) revertIfNoReturn() ifFlag(flag) internal view returns(S storage) {
+        return s;
+    }
+
+}
+// ----

test/libsolidity/syntaxTests/controlFlow/storageReturn/modifier_warn.sol

@@ -0,0 +1,22 @@
+contract C {
+    modifier revertIfNoReturn() {
+        _;
+        revert();
+    }
+    modifier ifFlag(bool flag) {
+        if (flag)
+            _;
+    }
+    struct S { uint a; }
+    S s;
+    function f(bool flag) ifFlag(flag) internal view returns(S storage) {
+        return s;
+    }
+
+    function g(bool flag) ifFlag(flag) revertIfNoReturn() internal view returns(S storage) {
+        return s;
+    }
+}
+// ----
+// Warning: (249-250): This variable is of storage pointer type and might be returned without assignment. This can cause storage corruption. Assign the variable (potentially from itself) to remove this warning.
+// Warning: (367-368): This variable is of storage pointer type and might be returned without assignment. This can cause storage corruption. Assign the variable (potentially from itself) to remove this warning.

test/libsolidity/syntaxTests/controlFlow/storageReturn/revert_fine.sol

@@ -0,0 +1,12 @@
+contract C {
+    struct S { bool f; }
+    S s;
+    function f() internal pure returns (S storage) {
+        revert();
+    }
+    function g(bool flag) internal view returns (S storage c) {
+        if (flag) c = s;
+        else revert();
+    }
+}
+// ----

test/libsolidity/syntaxTests/controlFlow/storageReturn/short_circuit_fine.sol

@@ -0,0 +1,11 @@
+contract C {
+    struct S { bool f; }
+    S s;
+    function f() internal view returns (S storage c) {
+        (c = s).f && false;
+    }
+    function g() internal view returns (S storage c) {
+        (c = s).f || true;
+    }
+}
+// ----

test/libsolidity/syntaxTests/controlFlow/storageReturn/short_circuit_warn.sol

@@ -0,0 +1,18 @@
+contract C {
+    struct S { bool f; }
+    S s;
+    function f() internal view returns (S storage c) {
+        false && (c = s).f;
+    }
+    function g() internal view returns (S storage c) {
+        true || (c = s).f;
+    }
+    function h() internal view returns (S storage c) {
+        // expect warning, although this is always fine
+        true && (false || (c = s).f);
+    }
+}
+// ----
+// Warning: (87-98): This variable is of storage pointer type and might be returned without assignment. This can cause storage corruption. Assign the variable (potentially from itself) to remove this warning.
+// Warning: (176-187): This variable is of storage pointer type and might be returned without assignment. This can cause storage corruption. Assign the variable (potentially from itself) to remove this warning.
+// Warning: (264-275): This variable is of storage pointer type and might be returned without assignment. This can cause storage corruption. Assign the variable (potentially from itself) to remove this warning.

test/libsolidity/syntaxTests/controlFlow/storageReturn/smoke.sol

@@ -0,0 +1,10 @@
+contract C {
+    struct S { bool f; }
+    S s;
+    function f() internal pure {}
+    function g() internal view returns (S storage) { return s; }
+    function h() internal view returns (S storage c) { return s; }
+    function i() internal view returns (S storage c) { c = s; }
+    function j() internal view returns (S storage c) { (c) = s; }
+}
+// ----

test/libsolidity/syntaxTests/controlFlow/storageReturn/ternary_fine.sol

@@ -0,0 +1,14 @@
+contract C {
+    struct S { bool f; }
+    S s;
+    function f(bool flag) internal view returns (S storage c) {
+        flag ? c = s : c = s;
+    }
+    function g(bool flag) internal view returns (S storage c) {
+        flag ? c = s : (c = s);
+    }
+    function h(bool flag) internal view returns (S storage c) {
+        flag ? (c = s).f : (c = s).f;
+    }
+}
+// ----

test/libsolidity/syntaxTests/controlFlow/storageReturn/ternary_warn.sol

@@ -0,0 +1,13 @@
+contract C {
+    struct S { bool f; }
+    S s;
+    function f(bool flag) internal view returns (S storage c) {
+        flag ? (c = s).f : false;
+    }
+    function g(bool flag) internal view returns (S storage c) {
+        flag ? false : (c = s).f;
+    }
+}
+// ----
+// Warning: (96-107): This variable is of storage pointer type and might be returned without assignment. This can cause storage corruption. Assign the variable (potentially from itself) to remove this warning.
+// Warning: (200-211): This variable is of storage pointer type and might be returned without assignment. This can cause storage corruption. Assign the variable (potentially from itself) to remove this warning.

test/libsolidity/syntaxTests/controlFlow/storageReturn/throw_fine.sol

@@ -0,0 +1,9 @@
+contract C {
+    struct S { bool f; }
+    S s;
+    function f() internal pure returns (S storage) {
+        throw;
+    }
+}
+// ----
+// Warning: (108-113): "throw" is deprecated in favour of "revert()", "require()" and "assert()".

test/libsolidity/syntaxTests/controlFlow/storageReturn/tuple_fine.sol

@@ -0,0 +1,12 @@
+contract C {
+    struct S { bool f; }
+    S s;
+    function f() internal view returns (S storage, uint) {
+        return (s,2);
+    }
+    function g() internal view returns (S storage c) {
+        uint a;
+        (c, a) = f();
+    }
+}
+// ----

test/libsolidity/syntaxTests/controlFlow/storageReturn/while_fine.sol

@@ -0,0 +1,19 @@
+contract C {
+    struct S { bool f; }
+    S s;
+    function f() internal view returns (S storage c) {
+        while((c = s).f) {
+        }
+    }
+    function g() internal view returns (S storage c) {
+        c = s;
+        while(false) {
+        }
+    }
+    function h() internal view returns (S storage c) {
+        while(false) {
+        }
+        c = s;
+    }
+}
+// ----

test/libsolidity/syntaxTests/controlFlow/storageReturn/while_warn.sol

@@ -0,0 +1,11 @@
+contract C {
+    struct S { bool f; }
+    S s;
+    function f() internal view returns (S storage c) {
+        while(false) {
+            c = s;
+        }
+    }
+}
+// ----
+// Warning: (87-98): This variable is of storage pointer type and might be returned without assignment. This can cause storage corruption. Assign the variable (potentially from itself) to remove this warning.