Merge pull request #4306 from ethereum/remove_050_workaround_scoping

[BREAKING] C99 scoping rules by default (remove 050 workaround)

2 files changed, 23 insertions, 77 deletions

diff --git a/docs/contracts.rst b/docs/contracts.rst
index 4dd185aa..5e7eab80 100644
--- a/docs/contracts.rst
+++ b/docs/contracts.rst
@@ -1323,6 +1323,7 @@ custom types without the overhead of external function calls:
             if (carry > 0) {
                 // too bad, we have to add a limb
                 uint[] memory newLimbs = new uint[](r.limbs.length + 1);
+                uint i;
                 for (i = 0; i < r.limbs.length; ++i)
                     newLimbs[i] = r.limbs[i];
                 newLimbs[i] = carry;
diff --git a/docs/control-structures.rst b/docs/control-structures.rst
index 7849d15a..cc1f7ca5 100644
--- a/docs/control-structures.rst
+++ b/docs/control-structures.rst
@@ -325,74 +325,7 @@ is ``false``. The default value for the ``uint`` or ``int`` types is ``0``. For
 element will be initialized to the default value corresponding to its type. Finally, for dynamically-sized arrays, ``bytes``
 and ``string``, the default value is an empty array or string.
 
-A variable declared anywhere within a function will be in scope for the *entire function*, regardless of where it is declared
-(this will change soon, see below).
-This happens because Solidity inherits its scoping rules from JavaScript.
-This is in contrast to many languages where variables are only scoped where they are declared until the end of the semantic block.
-As a result, the following code is illegal and cause the compiler to throw an error, ``Identifier already declared``:
-
-::
-
-    // This will not compile
-
-    pragma solidity ^0.4.16;
-
-    contract ScopingErrors {
-        function scoping() public {
-            uint i = 0;
-
-            while (i++ < 1) {
-                uint same1 = 0;
-            }
-
-            while (i++ < 2) {
-                uint same1 = 0;// Illegal, second declaration of same1
-            }
-        }
-
-        function minimalScoping() public {
-            {
-                uint same2 = 0;
-            }
-
-            {
-                uint same2 = 0;// Illegal, second declaration of same2
-            }
-        }
-
-        function forLoopScoping() public {
-            for (uint same3 = 0; same3 < 1; same3++) {
-            }
-
-            for (uint same3 = 0; same3 < 1; same3++) {// Illegal, second declaration of same3
-            }
-        }
-    }
-
-In addition to this, if a variable is declared, it will be initialized at the beginning of the function to its default value.
-As a result, the following code is legal, despite being poorly written:
-
-::
-
-    pragma solidity ^0.4.0;
-
-    contract C {
-        function foo() public pure returns (uint) {
-            // baz is implicitly initialized as 0
-            uint bar = 5;
-            if (true) {
-                bar += baz;
-            } else {
-                uint baz = 10;// never executes
-            }
-            return bar;// returns 5
-        }
-    }
-
-Scoping starting from Version 0.5.0
------------------------------------
-
-Starting from version 0.5.0, Solidity will change to the more widespread scoping rules of C99
+Scoping in Solidity follows the widespread scoping rules of C99
 (and many other languages): Variables are visible from the point right after their declaration
 until the end of a ``{ }``-block. As an exception to this rule, variables declared in the
 initialization part of a for-loop are only visible until the end of the for-loop.
@@ -401,17 +334,12 @@ Variables and other items declared outside of a code block, for example function
 user-defined types, etc., do not change their scoping behaviour. This means you can
 use state variables before they are declared and call functions recursively.
 
-These rules are already introduced now as an experimental feature.
-
 As a consequence, the following examples will compile without warnings, since
-the two variables have the same name but disjoint scopes. In non-0.5.0-mode,
-they have the same scope (the function ``minimalScoping``) and thus it does
-not compile there.
+the two variables have the same name but disjoint scopes.
 
 ::
 
-    pragma solidity ^0.4.0;
-    pragma experimental "v0.5.0";
+    pragma solidity >0.4.24;
     contract C {
         function minimalScoping() pure public {
             {
@@ -430,8 +358,7 @@ In any case, you will get a warning about the outer variable being shadowed.
 
 ::
 
-    pragma solidity ^0.4.0;
-    pragma experimental "v0.5.0";
+    pragma solidity >0.4.24;
     contract C {
         function f() pure public returns (uint) {
             uint x = 1;
@@ -443,6 +370,24 @@ In any case, you will get a warning about the outer variable being shadowed.
         }
     }
 
+.. warning::
+    Before version 0.5.0 Solidity followed the same scoping rules as JavaScript, that is, a variable declared anywhere within a function would be in scope
+    for the entire function, regardless where it was declared. Note that this is a breaking change. The following example shows a code snippet that used
+    to compile but leads to an error starting from version 0.5.0.
+
+ ::
+
+    // This will not compile
+
+    pragma solidity >0.4.24;
+    contract C {
+        function f() pure public returns (uint) {
+            x = 2;
+            uint x;
+            return x;
+        }
+    }
+
 .. index:: ! exception, ! throw, ! assert, ! require, ! revert
 
 Error handling: Assert, Require, Revert and Exceptions