`Array`: Relax `slice` bound checks to properly handle negative indices

The same is done for `Vector` (and thus `Packed*Array`).

`begin` and `end` can now take any value and will be clamped to
`[-size(), size()]`. Negative values are a shorthand for indexing the array
from the last element upward.

`end` is given a default `INT_MAX` value (which will be clamped to `size()`)
so that the `end` parameter can be omitted to go from `begin` to the max size
of the array.

This makes `slice` works similarly to numpy's and JavaScript's.

10 files changed, 39 insertions, 13 deletions

diff --git a/doc/classes/Array.xml b/doc/classes/Array.xml
index 5b1861bc9a..badd8a4966 100644
--- a/doc/classes/Array.xml
+++ b/doc/classes/Array.xml
@@ -445,13 +445,14 @@
 		<method name="slice" qualifiers="const">
 			<return type="Array" />
 			<argument index="0" name="begin" type="int" />
-			<argument index="1" name="end" type="int" />
+			<argument index="1" name="end" type="int" default="2147483647" />
 			<argument index="2" name="step" type="int" default="1" />
 			<argument index="3" name="deep" type="bool" default="false" />
 			<description>
 				Returns the slice of the [Array], from [code]begin[/code] (inclusive) to [code]end[/code] (exclusive), as a new [Array].
-				If [code]end[/code] is negative, it will be relative to the end of the array.
-				If specified, [code]step[/code] is the relative index between source elements.
+				The absolute value of [code]begin[/code] and [code]end[/code] will be clamped to the array size, so the default value for [code]end[/code] makes it slice to the size of the array by default (i.e. [code]arr.slice(1)[/code] is a shorthand for [code]arr.slice(1, arr.size())[/code]).
+				If either [code]begin[/code] or [code]end[/code] are negative, they will be relative to the end of the array (i.e. [code]arr.slice(0, -2)[/code] is a shorthand for [code]arr.slice(0, arr.size() - 2)[/code]).
+				If specified, [code]step[/code] is the relative index between source elements. It can be negative, then [code]begin[/code] must be higher than [code]end[/code]. For example, [code][0, 1, 2, 3, 4, 5].slice(5, 1, -2)[/code] returns [code][5, 3][/code]).
 				If [code]deep[/code] is true, each element will be copied by value rather than by reference.
 			</description>
 		</method>
diff --git a/doc/classes/PackedByteArray.xml b/doc/classes/PackedByteArray.xml
index 686854ffe8..3dc8307d44 100644
--- a/doc/classes/PackedByteArray.xml
+++ b/doc/classes/PackedByteArray.xml
@@ -369,10 +369,11 @@
 		<method name="slice" qualifiers="const">
 			<return type="PackedByteArray" />
 			<argument index="0" name="begin" type="int" />
-			<argument index="1" name="end" type="int" />
+			<argument index="1" name="end" type="int" default="2147483647" />
 			<description>
 				Returns the slice of the [PackedByteArray], from [code]begin[/code] (inclusive) to [code]end[/code] (exclusive), as a new [PackedByteArray].
-				If [code]end[/code]is negative, it will be relative to the end of the array.
+				The absolute value of [code]begin[/code] and [code]end[/code] will be clamped to the array size, so the default value for [code]end[/code] makes it slice to the size of the array by default (i.e. [code]arr.slice(1)[/code] is a shorthand for [code]arr.slice(1, arr.size())[/code]).
+				If either [code]begin[/code] or [code]end[/code] are negative, they will be relative to the end of the array (i.e. [code]arr.slice(0, -2)[/code] is a shorthand for [code]arr.slice(0, arr.size() - 2)[/code]).
 			</description>
 		</method>
 		<method name="sort">
diff --git a/doc/classes/PackedColorArray.xml b/doc/classes/PackedColorArray.xml
index d875549319..8aac7d1bf4 100644
--- a/doc/classes/PackedColorArray.xml
+++ b/doc/classes/PackedColorArray.xml
@@ -132,8 +132,11 @@
 		<method name="slice" qualifiers="const">
 			<return type="PackedColorArray" />
 			<argument index="0" name="begin" type="int" />
-			<argument index="1" name="end" type="int" />
+			<argument index="1" name="end" type="int" default="2147483647" />
 			<description>
+				Returns the slice of the [PackedColorArray], from [code]begin[/code] (inclusive) to [code]end[/code] (exclusive), as a new [PackedColorArray].
+				The absolute value of [code]begin[/code] and [code]end[/code] will be clamped to the array size, so the default value for [code]end[/code] makes it slice to the size of the array by default (i.e. [code]arr.slice(1)[/code] is a shorthand for [code]arr.slice(1, arr.size())[/code]).
+				If either [code]begin[/code] or [code]end[/code] are negative, they will be relative to the end of the array (i.e. [code]arr.slice(0, -2)[/code] is a shorthand for [code]arr.slice(0, arr.size() - 2)[/code]).
 			</description>
 		</method>
 		<method name="sort">
diff --git a/doc/classes/PackedFloat32Array.xml b/doc/classes/PackedFloat32Array.xml
index 6c77c4bee2..0e66dd7967 100644
--- a/doc/classes/PackedFloat32Array.xml
+++ b/doc/classes/PackedFloat32Array.xml
@@ -133,8 +133,11 @@
 		<method name="slice" qualifiers="const">
 			<return type="PackedFloat32Array" />
 			<argument index="0" name="begin" type="int" />
-			<argument index="1" name="end" type="int" />
+			<argument index="1" name="end" type="int" default="2147483647" />
 			<description>
+				Returns the slice of the [PackedFloat32Array], from [code]begin[/code] (inclusive) to [code]end[/code] (exclusive), as a new [PackedFloat32Array].
+				The absolute value of [code]begin[/code] and [code]end[/code] will be clamped to the array size, so the default value for [code]end[/code] makes it slice to the size of the array by default (i.e. [code]arr.slice(1)[/code] is a shorthand for [code]arr.slice(1, arr.size())[/code]).
+				If either [code]begin[/code] or [code]end[/code] are negative, they will be relative to the end of the array (i.e. [code]arr.slice(0, -2)[/code] is a shorthand for [code]arr.slice(0, arr.size() - 2)[/code]).
 			</description>
 		</method>
 		<method name="sort">
diff --git a/doc/classes/PackedFloat64Array.xml b/doc/classes/PackedFloat64Array.xml
index a8282c099a..eaad4fec54 100644
--- a/doc/classes/PackedFloat64Array.xml
+++ b/doc/classes/PackedFloat64Array.xml
@@ -133,8 +133,11 @@
 		<method name="slice" qualifiers="const">
 			<return type="PackedFloat64Array" />
 			<argument index="0" name="begin" type="int" />
-			<argument index="1" name="end" type="int" />
+			<argument index="1" name="end" type="int" default="2147483647" />
 			<description>
+				Returns the slice of the [PackedFloat64Array], from [code]begin[/code] (inclusive) to [code]end[/code] (exclusive), as a new [PackedFloat64Array].
+				The absolute value of [code]begin[/code] and [code]end[/code] will be clamped to the array size, so the default value for [code]end[/code] makes it slice to the size of the array by default (i.e. [code]arr.slice(1)[/code] is a shorthand for [code]arr.slice(1, arr.size())[/code]).
+				If either [code]begin[/code] or [code]end[/code] are negative, they will be relative to the end of the array (i.e. [code]arr.slice(0, -2)[/code] is a shorthand for [code]arr.slice(0, arr.size() - 2)[/code]).
 			</description>
 		</method>
 		<method name="sort">
diff --git a/doc/classes/PackedInt32Array.xml b/doc/classes/PackedInt32Array.xml
index da26e93b96..ec698ed8e5 100644
--- a/doc/classes/PackedInt32Array.xml
+++ b/doc/classes/PackedInt32Array.xml
@@ -133,8 +133,11 @@
 		<method name="slice" qualifiers="const">
 			<return type="PackedInt32Array" />
 			<argument index="0" name="begin" type="int" />
-			<argument index="1" name="end" type="int" />
+			<argument index="1" name="end" type="int" default="2147483647" />
 			<description>
+				Returns the slice of the [PackedInt32Array], from [code]begin[/code] (inclusive) to [code]end[/code] (exclusive), as a new [PackedInt32Array].
+				The absolute value of [code]begin[/code] and [code]end[/code] will be clamped to the array size, so the default value for [code]end[/code] makes it slice to the size of the array by default (i.e. [code]arr.slice(1)[/code] is a shorthand for [code]arr.slice(1, arr.size())[/code]).
+				If either [code]begin[/code] or [code]end[/code] are negative, they will be relative to the end of the array (i.e. [code]arr.slice(0, -2)[/code] is a shorthand for [code]arr.slice(0, arr.size() - 2)[/code]).
 			</description>
 		</method>
 		<method name="sort">
diff --git a/doc/classes/PackedInt64Array.xml b/doc/classes/PackedInt64Array.xml
index 9ddf43a837..ec4b3c1209 100644
--- a/doc/classes/PackedInt64Array.xml
+++ b/doc/classes/PackedInt64Array.xml
@@ -133,8 +133,11 @@
 		<method name="slice" qualifiers="const">
 			<return type="PackedInt64Array" />
 			<argument index="0" name="begin" type="int" />
-			<argument index="1" name="end" type="int" />
+			<argument index="1" name="end" type="int" default="2147483647" />
 			<description>
+				Returns the slice of the [PackedInt64Array], from [code]begin[/code] (inclusive) to [code]end[/code] (exclusive), as a new [PackedInt64Array].
+				The absolute value of [code]begin[/code] and [code]end[/code] will be clamped to the array size, so the default value for [code]end[/code] makes it slice to the size of the array by default (i.e. [code]arr.slice(1)[/code] is a shorthand for [code]arr.slice(1, arr.size())[/code]).
+				If either [code]begin[/code] or [code]end[/code] are negative, they will be relative to the end of the array (i.e. [code]arr.slice(0, -2)[/code] is a shorthand for [code]arr.slice(0, arr.size() - 2)[/code]).
 			</description>
 		</method>
 		<method name="sort">
diff --git a/doc/classes/PackedStringArray.xml b/doc/classes/PackedStringArray.xml
index 439d59dde7..ebe9c591b8 100644
--- a/doc/classes/PackedStringArray.xml
+++ b/doc/classes/PackedStringArray.xml
@@ -133,8 +133,11 @@
 		<method name="slice" qualifiers="const">
 			<return type="PackedStringArray" />
 			<argument index="0" name="begin" type="int" />
-			<argument index="1" name="end" type="int" />
+			<argument index="1" name="end" type="int" default="2147483647" />
 			<description>
+				Returns the slice of the [PackedStringArray], from [code]begin[/code] (inclusive) to [code]end[/code] (exclusive), as a new [PackedStringArray].
+				The absolute value of [code]begin[/code] and [code]end[/code] will be clamped to the array size, so the default value for [code]end[/code] makes it slice to the size of the array by default (i.e. [code]arr.slice(1)[/code] is a shorthand for [code]arr.slice(1, arr.size())[/code]).
+				If either [code]begin[/code] or [code]end[/code] are negative, they will be relative to the end of the array (i.e. [code]arr.slice(0, -2)[/code] is a shorthand for [code]arr.slice(0, arr.size() - 2)[/code]).
 			</description>
 		</method>
 		<method name="sort">
diff --git a/doc/classes/PackedVector2Array.xml b/doc/classes/PackedVector2Array.xml
index 8c4f052016..d72ca4b4bb 100644
--- a/doc/classes/PackedVector2Array.xml
+++ b/doc/classes/PackedVector2Array.xml
@@ -133,8 +133,11 @@
 		<method name="slice" qualifiers="const">
 			<return type="PackedVector2Array" />
 			<argument index="0" name="begin" type="int" />
-			<argument index="1" name="end" type="int" />
+			<argument index="1" name="end" type="int" default="2147483647" />
 			<description>
+				Returns the slice of the [PackedVector2Array], from [code]begin[/code] (inclusive) to [code]end[/code] (exclusive), as a new [PackedVector2Array].
+				The absolute value of [code]begin[/code] and [code]end[/code] will be clamped to the array size, so the default value for [code]end[/code] makes it slice to the size of the array by default (i.e. [code]arr.slice(1)[/code] is a shorthand for [code]arr.slice(1, arr.size())[/code]).
+				If either [code]begin[/code] or [code]end[/code] are negative, they will be relative to the end of the array (i.e. [code]arr.slice(0, -2)[/code] is a shorthand for [code]arr.slice(0, arr.size() - 2)[/code]).
 			</description>
 		</method>
 		<method name="sort">
diff --git a/doc/classes/PackedVector3Array.xml b/doc/classes/PackedVector3Array.xml
index 8229af984d..cbae0c40e7 100644
--- a/doc/classes/PackedVector3Array.xml
+++ b/doc/classes/PackedVector3Array.xml
@@ -132,8 +132,11 @@
 		<method name="slice" qualifiers="const">
 			<return type="PackedVector3Array" />
 			<argument index="0" name="begin" type="int" />
-			<argument index="1" name="end" type="int" />
+			<argument index="1" name="end" type="int" default="2147483647" />
 			<description>
+				Returns the slice of the [PackedVector3Array], from [code]begin[/code] (inclusive) to [code]end[/code] (exclusive), as a new [PackedVector3Array].
+				The absolute value of [code]begin[/code] and [code]end[/code] will be clamped to the array size, so the default value for [code]end[/code] makes it slice to the size of the array by default (i.e. [code]arr.slice(1)[/code] is a shorthand for [code]arr.slice(1, arr.size())[/code]).
+				If either [code]begin[/code] or [code]end[/code] are negative, they will be relative to the end of the array (i.e. [code]arr.slice(0, -2)[/code] is a shorthand for [code]arr.slice(0, arr.size() - 2)[/code]).
 			</description>
 		</method>
 		<method name="sort">