Warn about unreachable code.

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

@@ -46,7 +46,11 @@ contract C {
 }
 // ----
 // TypeError: (87-98): This variable is of storage pointer type and can be returned without prior assignment.
+// Warning: (146-151): Unreachable code.
+// Warning: (169-174): Unreachable code.
 // TypeError: (223-234): This variable is of storage pointer type and can be returned without prior assignment.
+// Warning: (316-321): Unreachable code.
 // TypeError: (440-451): This variable is of storage pointer type and can be returned without prior assignment.
 // TypeError: (654-665): This variable is of storage pointer type and can be returned without prior assignment.
 // TypeError: (871-882): This variable is of storage pointer type and can be returned without prior assignment.
+// Warning: (933-938): Unreachable code.

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

@@ -29,3 +29,4 @@ contract C {
     }
 }
 // ----
+// Warning: (567-572): Unreachable code.

test/libsolidity/syntaxTests/controlFlow/uninitializedAccess/always_revert.sol

@@ -5,4 +5,6 @@ contract C {
         revert();
         b;
     }
-}
+}
+// ----
+// Warning: (125-126): Unreachable code.

test/libsolidity/syntaxTests/controlFlow/uninitializedAccess/unreachable.sol

@@ -8,3 +8,4 @@ contract C {
     }
 }
 // ----
+// Warning: (112-135): Unreachable code.

test/libsolidity/syntaxTests/controlFlow/unreachableCode/comment_fine.sol

@@ -0,0 +1,6 @@
+contract C {
+    function f() public pure {
+        return;
+        // unreachable comment
+    }
+}

test/libsolidity/syntaxTests/controlFlow/unreachableCode/constant_condition.sol

@@ -0,0 +1,8 @@
+contract C {
+    function f() public pure {
+        if (false) {
+            return; // unreachable, but not yet detected
+        }
+        return;
+    }
+}

test/libsolidity/syntaxTests/controlFlow/unreachableCode/do_while_continue.sol

@@ -0,0 +1,12 @@
+contract C {
+    function f() public pure {
+        do {
+            uint a = 42; a;
+            continue;
+            return; // this is unreachable
+        } while(false);
+        return; // this is still reachable
+    }
+}
+// ----
+// Warning: (119-126): Unreachable code.

test/libsolidity/syntaxTests/controlFlow/unreachableCode/double_return.sol

@@ -0,0 +1,8 @@
+contract C {
+    function f() public pure returns (uint) {
+        return 0;
+        return 0;
+    }
+}
+// ----
+// Warning: (85-93): Unreachable code.

test/libsolidity/syntaxTests/controlFlow/unreachableCode/double_revert.sol

@@ -0,0 +1,8 @@
+contract C {
+    function f() public pure {
+        revert();
+        revert();
+    }
+}
+// ----
+// Warning: (70-78): Unreachable code.

test/libsolidity/syntaxTests/controlFlow/unreachableCode/for_break.sol

@@ -0,0 +1,12 @@
+contract C {
+    function f() public pure {
+        for (uint a = 0; a < 1; a++) {
+            break;
+            uint b = 42; b;
+        }
+        return;
+    }
+}
+// ----
+// Warning: (76-79): Unreachable code.
+// Warning: (114-128): Unreachable code.

test/libsolidity/syntaxTests/controlFlow/unreachableCode/if_both_return.sol

@@ -0,0 +1,12 @@
+contract C {
+    function f(bool c) public pure {
+        if (c) {
+            return;
+        } else {
+            return;
+        }
+        return; // unreachable
+    }
+}
+// ----
+// Warning: (142-149): Unreachable code.

test/libsolidity/syntaxTests/controlFlow/unreachableCode/revert.sol

@@ -0,0 +1,8 @@
+contract C {
+    function f() public pure {
+        revert();
+        uint a = 0; a;
+    }
+}
+// ----
+// Warning: (70-83): Unreachable code.

test/libsolidity/syntaxTests/controlFlow/unreachableCode/revert_empty.sol

@@ -0,0 +1,8 @@
+contract C {
+    function f() public pure {
+        revert();
+        for(int i = 0; i < 3; i++) { f(); }
+    }
+}
+// ----
+// Warning: (70-105): Unreachable code.

test/libsolidity/syntaxTests/controlFlow/unreachableCode/while_break.sol

@@ -0,0 +1,12 @@
+contract C {
+    function f() public pure {
+        uint a = 0;
+        while (a < 100) {
+            a++;
+            break;
+            a--;
+        }
+    }
+}
+// ----
+// Warning: (138-141): Unreachable code.

test/libsolidity/syntaxTests/controlFlow/unreachableCode/while_continue.sol

@@ -0,0 +1,11 @@
+contract C {
+    function f() public pure {
+        while(true) {
+            continue;
+            return;
+        }
+        return; // this is unreachable as well, but currently undetected (needs to consider constant condition "true")
+    }
+}
+// ----
+// Warning: (100-107): Unreachable code.