From 98d52beba3f989b3a5eeaba2d257de8de5df60a7 Mon Sep 17 00:00:00 2001
From: Erik Kundt <bitshift@posteo.org>
Date: Wed, 16 May 2018 17:18:30 +0200
Subject: [PATCH] Adds syntax tests, documentation and changelog entry.

Refines comment for array utility function.
---
 Changelog.md                                              | 2 ++
 docs/types.rst                                            | 4 +++-
 libsolidity/codegen/ArrayUtils.cpp                        | 2 +-
 libsolidity/codegen/ArrayUtils.h                          | 2 +-
 test/libsolidity/syntaxTests/array/array_pop.sol          | 7 +++++++
 test/libsolidity/syntaxTests/array/array_pop_arg.sol      | 8 ++++++++
 test/libsolidity/syntaxTests/array/bytes_pop.sol          | 7 +++++++
 .../syntaxTests/array/dynamic_memory_array_pop.sol        | 8 ++++++++
 ...array_length_cannot_be_constant_function_parameter.sol | 0
 .../length}/can_be_constant_in_function.sol               | 0
 .../length}/can_be_constant_in_struct.sol                 | 0
 .../length}/can_be_recursive_constant.sol                 | 0
 .../{arrayLength => array/length}/cannot_be_function.sol  | 0
 .../length}/cannot_be_function_call.sol                   | 0
 .../length}/complex_cyclic_constant.sol                   | 0
 .../length}/const_cannot_be_fractional.sol                | 0
 .../{arrayLength => array/length}/constant_var.sol        | 0
 .../{arrayLength => array/length}/cyclic_constant.sol     | 0
 .../{arrayLength => array/length}/inline_array.sol        | 0
 .../length}/invalid_expression_1.sol                      | 0
 .../length}/invalid_expression_2.sol                      | 0
 .../length}/invalid_expression_3.sol                      | 0
 .../length}/invalid_expression_4.sol                      | 0
 .../length}/invalid_expression_5.sol                      | 0
 .../length}/non_integer_constant_var.sol                  | 0
 .../length}/not_convertible_to_integer.sol                | 0
 .../{arrayLength => array/length}/parentheses.sol         | 0
 .../{arrayLength => array/length}/pure_functions.sol      | 0
 .../{arrayLength => array/length}/too_large.sol           | 0
 .../syntaxTests/{arrayLength => array/length}/tuples.sol  | 0
 test/libsolidity/syntaxTests/array/no_array_pop.sol       | 8 ++++++++
 .../syntaxTests/array/static_storage_array_pop.sol        | 8 ++++++++
 test/libsolidity/syntaxTests/array/string_pop.sol         | 8 ++++++++
 33 files changed, 61 insertions(+), 3 deletions(-)
 create mode 100644 test/libsolidity/syntaxTests/array/array_pop.sol
 create mode 100644 test/libsolidity/syntaxTests/array/array_pop_arg.sol
 create mode 100644 test/libsolidity/syntaxTests/array/bytes_pop.sol
 create mode 100644 test/libsolidity/syntaxTests/array/dynamic_memory_array_pop.sol
 rename test/libsolidity/syntaxTests/{arrayLength => array/length}/array_length_cannot_be_constant_function_parameter.sol (100%)
 rename test/libsolidity/syntaxTests/{arrayLength => array/length}/can_be_constant_in_function.sol (100%)
 rename test/libsolidity/syntaxTests/{arrayLength => array/length}/can_be_constant_in_struct.sol (100%)
 rename test/libsolidity/syntaxTests/{arrayLength => array/length}/can_be_recursive_constant.sol (100%)
 rename test/libsolidity/syntaxTests/{arrayLength => array/length}/cannot_be_function.sol (100%)
 rename test/libsolidity/syntaxTests/{arrayLength => array/length}/cannot_be_function_call.sol (100%)
 rename test/libsolidity/syntaxTests/{arrayLength => array/length}/complex_cyclic_constant.sol (100%)
 rename test/libsolidity/syntaxTests/{arrayLength => array/length}/const_cannot_be_fractional.sol (100%)
 rename test/libsolidity/syntaxTests/{arrayLength => array/length}/constant_var.sol (100%)
 rename test/libsolidity/syntaxTests/{arrayLength => array/length}/cyclic_constant.sol (100%)
 rename test/libsolidity/syntaxTests/{arrayLength => array/length}/inline_array.sol (100%)
 rename test/libsolidity/syntaxTests/{arrayLength => array/length}/invalid_expression_1.sol (100%)
 rename test/libsolidity/syntaxTests/{arrayLength => array/length}/invalid_expression_2.sol (100%)
 rename test/libsolidity/syntaxTests/{arrayLength => array/length}/invalid_expression_3.sol (100%)
 rename test/libsolidity/syntaxTests/{arrayLength => array/length}/invalid_expression_4.sol (100%)
 rename test/libsolidity/syntaxTests/{arrayLength => array/length}/invalid_expression_5.sol (100%)
 rename test/libsolidity/syntaxTests/{arrayLength => array/length}/non_integer_constant_var.sol (100%)
 rename test/libsolidity/syntaxTests/{arrayLength => array/length}/not_convertible_to_integer.sol (100%)
 rename test/libsolidity/syntaxTests/{arrayLength => array/length}/parentheses.sol (100%)
 rename test/libsolidity/syntaxTests/{arrayLength => array/length}/pure_functions.sol (100%)
 rename test/libsolidity/syntaxTests/{arrayLength => array/length}/too_large.sol (100%)
 rename test/libsolidity/syntaxTests/{arrayLength => array/length}/tuples.sol (100%)
 create mode 100644 test/libsolidity/syntaxTests/array/no_array_pop.sol
 create mode 100644 test/libsolidity/syntaxTests/array/static_storage_array_pop.sol
 create mode 100644 test/libsolidity/syntaxTests/array/string_pop.sol

diff --git a/Changelog.md b/Changelog.md
index c31aced2a..a1248868f 100644
--- a/Changelog.md
+++ b/Changelog.md
@@ -1,5 +1,7 @@
 ### 0.5.0 (unreleased)
 
+Language Features:
+ * General: Support ``pop()`` for storage arrays.
 
 Breaking Changes:
  * Disallow conversions between bytesX and uintY of different size.
diff --git a/docs/types.rst b/docs/types.rst
index 794a70de0..b3631f747 100644
--- a/docs/types.rst
+++ b/docs/types.rst
@@ -682,7 +682,7 @@ possible:
 It is planned to remove this restriction in the future but currently creates
 some complications because of how arrays are passed in the ABI.
 
-.. index:: ! array;length, length, push, !array;push
+.. index:: ! array;length, length, push, pop, !array;push, !array;pop
 
 Members
 ^^^^^^^
@@ -693,6 +693,8 @@ Members
     ``.length`` member. This does not happen automatically when attempting to access elements outside the current length. The size of memory arrays is fixed (but dynamic, i.e. it can depend on runtime parameters) once they are created.
 **push**:
      Dynamic storage arrays and ``bytes`` (not ``string``) have a member function called ``push`` that can be used to append an element at the end of the array. The function returns the new length.
+**pop**:
+     Dynamic storage arrays and ``bytes`` (not ``string``) have a member function called ``pop`` that can be used to remove an element from the end of the array.
 
 .. warning::
     It is not yet possible to use arrays of arrays in external functions.
diff --git a/libsolidity/codegen/ArrayUtils.cpp b/libsolidity/codegen/ArrayUtils.cpp
index d78e64a92..6bb9a9612 100644
--- a/libsolidity/codegen/ArrayUtils.cpp
+++ b/libsolidity/codegen/ArrayUtils.cpp
@@ -840,7 +840,7 @@ void ArrayUtils::popStorageArrayElement(ArrayType const& _type) const
 				let length := and(div(slot_value, 2), 0x1f)
 				if iszero(length) { invalid() }
 
-				// Zero-out the suffix inlcluding the least significant byte.
+				// Zero-out the suffix including the least significant byte.
 				let mask := sub(exp(0x100, sub(33, length)), 1)
 				length := sub(length, 1)
 				slot_value := or(and(not(mask), slot_value), mul(length, 2))
diff --git a/libsolidity/codegen/ArrayUtils.h b/libsolidity/codegen/ArrayUtils.h
index 84d591d7e..daf50bf52 100644
--- a/libsolidity/codegen/ArrayUtils.h
+++ b/libsolidity/codegen/ArrayUtils.h
@@ -73,7 +73,7 @@ public:
 	/// Stack pre: reference (excludes byte offset)
 	/// Stack post: new_length
 	void incrementDynamicArraySize(ArrayType const& _type) const;
-	/// Decrements the size of a dynamic array by one if length is nonzero. Returns otherwise.
+	/// Decrements the size of a dynamic array by one if length is nonzero. Causes an invalid instruction otherwise.
 	/// Clears the removed data element. In case of a byte array, this might move the data.
 	/// Stack pre: reference
 	/// Stack post:
diff --git a/test/libsolidity/syntaxTests/array/array_pop.sol b/test/libsolidity/syntaxTests/array/array_pop.sol
new file mode 100644
index 000000000..3804f911f
--- /dev/null
+++ b/test/libsolidity/syntaxTests/array/array_pop.sol
@@ -0,0 +1,7 @@
+contract C {
+    uint[] data;
+    function test() public {
+      data.pop();
+    }
+}
+// ----
diff --git a/test/libsolidity/syntaxTests/array/array_pop_arg.sol b/test/libsolidity/syntaxTests/array/array_pop_arg.sol
new file mode 100644
index 000000000..bb7803e28
--- /dev/null
+++ b/test/libsolidity/syntaxTests/array/array_pop_arg.sol
@@ -0,0 +1,8 @@
+contract C {
+    uint[] data;
+    function test() public {
+      data.pop(5);
+    }
+}
+// ----
+// TypeError: (65-76): Wrong argument count for function call: 1 arguments given but expected 0.
diff --git a/test/libsolidity/syntaxTests/array/bytes_pop.sol b/test/libsolidity/syntaxTests/array/bytes_pop.sol
new file mode 100644
index 000000000..cd5aa0eb6
--- /dev/null
+++ b/test/libsolidity/syntaxTests/array/bytes_pop.sol
@@ -0,0 +1,7 @@
+contract C {
+    bytes data;
+    function test() public {
+      data.pop();
+    }
+}
+// ----
diff --git a/test/libsolidity/syntaxTests/array/dynamic_memory_array_pop.sol b/test/libsolidity/syntaxTests/array/dynamic_memory_array_pop.sol
new file mode 100644
index 000000000..5a79afc93
--- /dev/null
+++ b/test/libsolidity/syntaxTests/array/dynamic_memory_array_pop.sol
@@ -0,0 +1,8 @@
+contract C {
+    function test() public {
+      uint[] memory data;
+      data.pop();
+    }
+}
+// ----
+// TypeError: (74-82): Member "pop" is not available in uint256[] memory outside of storage.
diff --git a/test/libsolidity/syntaxTests/arrayLength/array_length_cannot_be_constant_function_parameter.sol b/test/libsolidity/syntaxTests/array/length/array_length_cannot_be_constant_function_parameter.sol
similarity index 100%
rename from test/libsolidity/syntaxTests/arrayLength/array_length_cannot_be_constant_function_parameter.sol
rename to test/libsolidity/syntaxTests/array/length/array_length_cannot_be_constant_function_parameter.sol
diff --git a/test/libsolidity/syntaxTests/arrayLength/can_be_constant_in_function.sol b/test/libsolidity/syntaxTests/array/length/can_be_constant_in_function.sol
similarity index 100%
rename from test/libsolidity/syntaxTests/arrayLength/can_be_constant_in_function.sol
rename to test/libsolidity/syntaxTests/array/length/can_be_constant_in_function.sol
diff --git a/test/libsolidity/syntaxTests/arrayLength/can_be_constant_in_struct.sol b/test/libsolidity/syntaxTests/array/length/can_be_constant_in_struct.sol
similarity index 100%
rename from test/libsolidity/syntaxTests/arrayLength/can_be_constant_in_struct.sol
rename to test/libsolidity/syntaxTests/array/length/can_be_constant_in_struct.sol
diff --git a/test/libsolidity/syntaxTests/arrayLength/can_be_recursive_constant.sol b/test/libsolidity/syntaxTests/array/length/can_be_recursive_constant.sol
similarity index 100%
rename from test/libsolidity/syntaxTests/arrayLength/can_be_recursive_constant.sol
rename to test/libsolidity/syntaxTests/array/length/can_be_recursive_constant.sol
diff --git a/test/libsolidity/syntaxTests/arrayLength/cannot_be_function.sol b/test/libsolidity/syntaxTests/array/length/cannot_be_function.sol
similarity index 100%
rename from test/libsolidity/syntaxTests/arrayLength/cannot_be_function.sol
rename to test/libsolidity/syntaxTests/array/length/cannot_be_function.sol
diff --git a/test/libsolidity/syntaxTests/arrayLength/cannot_be_function_call.sol b/test/libsolidity/syntaxTests/array/length/cannot_be_function_call.sol
similarity index 100%
rename from test/libsolidity/syntaxTests/arrayLength/cannot_be_function_call.sol
rename to test/libsolidity/syntaxTests/array/length/cannot_be_function_call.sol
diff --git a/test/libsolidity/syntaxTests/arrayLength/complex_cyclic_constant.sol b/test/libsolidity/syntaxTests/array/length/complex_cyclic_constant.sol
similarity index 100%
rename from test/libsolidity/syntaxTests/arrayLength/complex_cyclic_constant.sol
rename to test/libsolidity/syntaxTests/array/length/complex_cyclic_constant.sol
diff --git a/test/libsolidity/syntaxTests/arrayLength/const_cannot_be_fractional.sol b/test/libsolidity/syntaxTests/array/length/const_cannot_be_fractional.sol
similarity index 100%
rename from test/libsolidity/syntaxTests/arrayLength/const_cannot_be_fractional.sol
rename to test/libsolidity/syntaxTests/array/length/const_cannot_be_fractional.sol
diff --git a/test/libsolidity/syntaxTests/arrayLength/constant_var.sol b/test/libsolidity/syntaxTests/array/length/constant_var.sol
similarity index 100%
rename from test/libsolidity/syntaxTests/arrayLength/constant_var.sol
rename to test/libsolidity/syntaxTests/array/length/constant_var.sol
diff --git a/test/libsolidity/syntaxTests/arrayLength/cyclic_constant.sol b/test/libsolidity/syntaxTests/array/length/cyclic_constant.sol
similarity index 100%
rename from test/libsolidity/syntaxTests/arrayLength/cyclic_constant.sol
rename to test/libsolidity/syntaxTests/array/length/cyclic_constant.sol
diff --git a/test/libsolidity/syntaxTests/arrayLength/inline_array.sol b/test/libsolidity/syntaxTests/array/length/inline_array.sol
similarity index 100%
rename from test/libsolidity/syntaxTests/arrayLength/inline_array.sol
rename to test/libsolidity/syntaxTests/array/length/inline_array.sol
diff --git a/test/libsolidity/syntaxTests/arrayLength/invalid_expression_1.sol b/test/libsolidity/syntaxTests/array/length/invalid_expression_1.sol
similarity index 100%
rename from test/libsolidity/syntaxTests/arrayLength/invalid_expression_1.sol
rename to test/libsolidity/syntaxTests/array/length/invalid_expression_1.sol
diff --git a/test/libsolidity/syntaxTests/arrayLength/invalid_expression_2.sol b/test/libsolidity/syntaxTests/array/length/invalid_expression_2.sol
similarity index 100%
rename from test/libsolidity/syntaxTests/arrayLength/invalid_expression_2.sol
rename to test/libsolidity/syntaxTests/array/length/invalid_expression_2.sol
diff --git a/test/libsolidity/syntaxTests/arrayLength/invalid_expression_3.sol b/test/libsolidity/syntaxTests/array/length/invalid_expression_3.sol
similarity index 100%
rename from test/libsolidity/syntaxTests/arrayLength/invalid_expression_3.sol
rename to test/libsolidity/syntaxTests/array/length/invalid_expression_3.sol
diff --git a/test/libsolidity/syntaxTests/arrayLength/invalid_expression_4.sol b/test/libsolidity/syntaxTests/array/length/invalid_expression_4.sol
similarity index 100%
rename from test/libsolidity/syntaxTests/arrayLength/invalid_expression_4.sol
rename to test/libsolidity/syntaxTests/array/length/invalid_expression_4.sol
diff --git a/test/libsolidity/syntaxTests/arrayLength/invalid_expression_5.sol b/test/libsolidity/syntaxTests/array/length/invalid_expression_5.sol
similarity index 100%
rename from test/libsolidity/syntaxTests/arrayLength/invalid_expression_5.sol
rename to test/libsolidity/syntaxTests/array/length/invalid_expression_5.sol
diff --git a/test/libsolidity/syntaxTests/arrayLength/non_integer_constant_var.sol b/test/libsolidity/syntaxTests/array/length/non_integer_constant_var.sol
similarity index 100%
rename from test/libsolidity/syntaxTests/arrayLength/non_integer_constant_var.sol
rename to test/libsolidity/syntaxTests/array/length/non_integer_constant_var.sol
diff --git a/test/libsolidity/syntaxTests/arrayLength/not_convertible_to_integer.sol b/test/libsolidity/syntaxTests/array/length/not_convertible_to_integer.sol
similarity index 100%
rename from test/libsolidity/syntaxTests/arrayLength/not_convertible_to_integer.sol
rename to test/libsolidity/syntaxTests/array/length/not_convertible_to_integer.sol
diff --git a/test/libsolidity/syntaxTests/arrayLength/parentheses.sol b/test/libsolidity/syntaxTests/array/length/parentheses.sol
similarity index 100%
rename from test/libsolidity/syntaxTests/arrayLength/parentheses.sol
rename to test/libsolidity/syntaxTests/array/length/parentheses.sol
diff --git a/test/libsolidity/syntaxTests/arrayLength/pure_functions.sol b/test/libsolidity/syntaxTests/array/length/pure_functions.sol
similarity index 100%
rename from test/libsolidity/syntaxTests/arrayLength/pure_functions.sol
rename to test/libsolidity/syntaxTests/array/length/pure_functions.sol
diff --git a/test/libsolidity/syntaxTests/arrayLength/too_large.sol b/test/libsolidity/syntaxTests/array/length/too_large.sol
similarity index 100%
rename from test/libsolidity/syntaxTests/arrayLength/too_large.sol
rename to test/libsolidity/syntaxTests/array/length/too_large.sol
diff --git a/test/libsolidity/syntaxTests/arrayLength/tuples.sol b/test/libsolidity/syntaxTests/array/length/tuples.sol
similarity index 100%
rename from test/libsolidity/syntaxTests/arrayLength/tuples.sol
rename to test/libsolidity/syntaxTests/array/length/tuples.sol
diff --git a/test/libsolidity/syntaxTests/array/no_array_pop.sol b/test/libsolidity/syntaxTests/array/no_array_pop.sol
new file mode 100644
index 000000000..44e54ad2f
--- /dev/null
+++ b/test/libsolidity/syntaxTests/array/no_array_pop.sol
@@ -0,0 +1,8 @@
+contract C {
+    uint data;
+    function test() public {
+      data.pop();
+    }
+}
+// ----
+// TypeError: (63-71): Member "pop" not found or not visible after argument-dependent lookup in uint256
diff --git a/test/libsolidity/syntaxTests/array/static_storage_array_pop.sol b/test/libsolidity/syntaxTests/array/static_storage_array_pop.sol
new file mode 100644
index 000000000..0af171ad5
--- /dev/null
+++ b/test/libsolidity/syntaxTests/array/static_storage_array_pop.sol
@@ -0,0 +1,8 @@
+contract C {
+    uint[3] data;
+    function test() public {
+      data.pop();
+    }
+}
+// ----
+// TypeError: (66-74): Member "pop" not found or not visible after argument-dependent lookup in uint256[3] storage ref
diff --git a/test/libsolidity/syntaxTests/array/string_pop.sol b/test/libsolidity/syntaxTests/array/string_pop.sol
new file mode 100644
index 000000000..2a46d0c3e
--- /dev/null
+++ b/test/libsolidity/syntaxTests/array/string_pop.sol
@@ -0,0 +1,8 @@
+contract C {
+    string data;
+    function test() public {
+      data.pop();
+    }
+}
+// ----
+// TypeError: (65-73): Member "pop" not found or not visible after argument-dependent lookup in string storage ref