breaking syntax change: ??x to x.? (#1095)

See #1023

This also renames Nullable/Maybe to Optional

Author: andrewrk

build.zig

@@ -75,7 +75,7 @@ pub fn build(b: *Builder) !void {
             cxx_compiler,
             "-print-file-name=libstdc++.a",
         });
-        const libstdcxx_path = ??mem.split(libstdcxx_path_padded, "\r\n").next();
+        const libstdcxx_path = mem.split(libstdcxx_path_padded, "\r\n").next().?;
         if (mem.eql(u8, libstdcxx_path, "libstdc++.a")) {
             warn(
                 \\Unable to determine path to libstdc++.a

doc/codegen.md

@@ -6,7 +6,7 @@ Every type has a "handle". If a type is a simple primitive type such as i32 or
 f64, the handle is "by value", meaning that we pass around the value itself when
 we refer to a value of that type.
 
-If a type is a container, error union, maybe type, slice, or array, then its
+If a type is a container, error union, optional type, slice, or array, then its
 handle is a pointer, and everywhere we refer to a value of this type we refer to
 a pointer.
 
@@ -19,7 +19,7 @@ Error union types are represented as:
         payload: T,
     }
 
-Maybe types are represented as:
+Optional types are represented as:
 
     struct {
         payload: T,
@@ -28,6 +28,6 @@ Maybe types are represented as:
 
 ## Data Optimizations
 
-Maybe pointer types are special: the 0x0 pointer value is used to represent a
-null pointer. Thus, instead of the struct above, maybe pointer types are
+Optional pointer types are special: the 0x0 pointer value is used to represent a
+null pointer. Thus, instead of the struct above, optional pointer types are
 represented as a `usize` in codegen and the handle is by value.