std.io: introduce buffered I/O and change API

I started working on #465 and made some corresponding std.io
API changes.

New structs:
 * std.io.FileInStream
 * std.io.FileOutStream
 * std.io.BufferedOutStream
 * std.io.BufferedInStream

Removed:
 * std.io.File.in_stream
 * std.io.File.out_stream

Now instead of &file.out_stream or &file.in_stream to get access to
the stream API for a file, you get it like this:

var file_in_stream = io.FileInStream.init(&file);
const in_stream = &file_in_stream.stream;

var file_out_stream = io.FileOutStream.init(&file);
const out_stream = &file_out_stream.stream;

This is evidence that we might not need any OOP features -
See #130.

1 files changed, 1 insertions, 0 deletions

diff --git a/src/ir.cpp b/src/ir.cpp
index ae48c1d369..1d63677024 100644
--- a/src/ir.cpp
+++ b/src/ir.cpp
@@ -12823,6 +12823,7 @@ static TypeTableEntry *ir_analyze_instruction_switch_target(IrAnalyze *ira,
         case TypeTableEntryIdEnum:
             {
                 TypeTableEntry *tag_type = target_type->data.enumeration.tag_type;
+                assert(tag_type != nullptr);
                 if (pointee_val) {
                     ConstExprValue *out_val = ir_build_const_from(ira, &switch_target_instruction->base);
                     bigint_init_unsigned(&out_val->data.x_bigint, pointee_val->data.x_enum.tag);