While TinyGo supports a big subset of the Go language, not everything is supported yet.
Here is a list of features that are supported:
complex128) and all regular control flow (including
deferkeyword is supported, with the exception of deferring a call on a function pointer. Immediately applied functions that are deferred are supported, however. In practice, function pointers are little used in deferred calls.
At the time of writing (2019-04-18), support for goroutines and channels is weak. There is some support, but you will often encounter compiler errors when trying to use concurrency in more complicated ways (for example with function pointers). Also, some things may unexpectedly allocate memory like calling a function that blocks. This situation should certainly improve in the future, but at the moment you shouldn’t rely on concurrency features to work well.
While TinyGo embeds the Clang compiler to parse
import "C" blocks, many features of Cgo are still unsupported. For example,
#cgo statements are currently ignored.
Many packages, especially in the standard library, rely on reflection to work. The
reflect package in the standards library is closely coupled to the main Go compilers and the runtime, so will have to be replaced. Work is underway that provides at least initial support for reflection.
Support for maps is still very limited and in general you shouldn’t rely on their availability. The main reason they are supported is so the
unicode package compiles.
To use maps, you will currently have to deal with the following limitations:
Due to the above missing pieces and because parts of the standard library depend on the particular compiler/runtime in use, many packages do not yet compile.
While not directly a language feature (the Go spec doesn’t mention it), garbage collection is important for most Go programs to make sure their memory usage stays in reasonable bounds.
Garbage collection is currently only supported on ARM microcontrollers (Cortex-M). For this platform, a simple conservative mark-sweep collector has been implemented. Other platforms will just allocate memory without ever freeing it.
Careful design may avoid memory allocations in main loops. You may want to compile with
-gc=none and look at link errors to find out where allocations happen: the compiler inserts calls to
runtime.alloc to allocate memory. For more information, see heap allocation.
Some features are little used and there hasn’t been a real need to implement them yet. These include:
recover(): this can be useful sometimes but in general most programs work just fine with a
panic()that simply aborts. Supporting
recover()will also likely increase code size so it has also been left out at the moment for that reason. When
recover()gets implemented, it will likely be disabled by default and can be enabled with a compiler flag.
imagbuiltins, as well as complex number constants, are all supported. Apart from the fact that complex number operations are little used, they are also hard to implement correctly.