all: remove support for Go 1.11 and 1.12

Go 1.13 has some important improvements that we would like to use, such
as the new integer literals and `errors.Is` which both arrived in Go
1.13.

.circleci/config.yml

@@ -342,18 +342,6 @@ commands:
             - /go/pkg/mod
 
 jobs:
-  test-llvm10-go111:
-    docker:
-      - image: circleci/golang:1.11-buster
-    steps:
-      - test-linux:
-          llvm: "10"
-  test-llvm10-go112:
-    docker:
-      - image: circleci/golang:1.12-buster
-    steps:
-      - test-linux:
-          llvm: "10"
   test-llvm10-go113:
     docker:
       - image: circleci/golang:1.13-buster
@@ -399,8 +387,6 @@ jobs:
 workflows:
   test-all:
     jobs:
-      - test-llvm10-go111
-      - test-llvm10-go112
       - test-llvm10-go113
       - test-llvm10-go114
       - test-llvm11-go115

BUILDING.md

@@ -23,7 +23,7 @@ different guide:
 LLVM, Clang and LLD are quite light on dependencies, requiring only standard
 build tools to be built. Go is of course necessary to build TinyGo itself.
 
-  * Go (1.11+)
+  * Go (1.13+)
   * Standard build tools (gcc/clang)
   * git
   * CMake
@@ -43,11 +43,6 @@ You can also store LLVM outside of the TinyGo root directory by setting the
 `LLVM_BUILDDIR`, `CLANG_SRC` and `LLD_SRC` make variables, but that is not
 covered by this guide.
 
-TinyGo uses Go modules, so if you clone TinyGo inside your GOPATH (and are using
-Go below 1.13), make sure that Go modules are enabled:
-
-    export GO111MODULE=on
-
 ## Build LLVM, Clang, LLD
 
 Before starting the build, you may want to set the following environment

builder/config.go

@@ -25,8 +25,8 @@ func NewConfig(options *compileopts.Options) (*compileopts.Config, error) {
 	if err != nil {
 		return nil, fmt.Errorf("could not read version from GOROOT (%v): %v", goroot, err)
 	}
-	if major != 1 || minor < 11 || minor > 16 {
-		return nil, fmt.Errorf("requires go version 1.11 through 1.16, got go%d.%d", major, minor)
+	if major != 1 || minor < 13 || minor > 16 {
+		return nil, fmt.Errorf("requires go version 1.13 through 1.16, got go%d.%d", major, minor)
 	}
 	clangHeaderPath := getClangHeaderPath(goenv.Get("TINYGOROOT"))
 	return &compileopts.Config{

go.mod

@@ -1,6 +1,6 @@
 module github.com/tinygo-org/tinygo
 
-go 1.11
+go 1.13
 
 require (
 	github.com/blakesmith/ar v0.0.0-20150311145944-8bd4349a67f2

src/runtime/strings_go111.go

@@ -1,20 +0,0 @@
-// +build !go1.12
-
-package runtime
-
-import "internal/bytealg"
-
-// The following functions provide compatibility with Go 1.11.
-// See the following:
-// https://github.com/tinygo-org/tinygo/issues/351
-// https://github.com/golang/go/commit/ad4a58e31501bce5de2aad90a620eaecdc1eecb8
-
-//go:linkname indexByte strings.IndexByte
-func indexByte(s string, c byte) int {
-	return bytealg.IndexByteString(s, c)
-}
-
-//go:linkname bytesEqual bytes.Equal
-func bytesEqual(a, b []byte) bool {
-	return bytealg.Equal(a, b)
-}