all: fix staticcheck warnings

This is a loose collection of small fixes flagged by staticcheck:

  - dead code
  - regexp expressions not using backticks (`foobar` / "foobar")
  - redundant types of slice and map initializers
  - misc other fixes

Not all of these seem very useful to me, but in particular dead code is
nice to fix. I've fixed them all just so that if there are problems,
they aren't hidden in the noise of less useful issues.

compiler/compiler.go

@@ -33,9 +33,6 @@ func init() {
 	llvm.InitializeAllAsmPrinters()
 }
 
-// The TinyGo import path.
-const tinygoPath = "github.com/tinygo-org/tinygo"
-
 // Config is the configuration for the compiler. Most settings should be copied
 // directly from compileopts.Config, it recreated here to decouple the compiler
 // package a bit and because it makes caching easier.
@@ -141,7 +138,6 @@ type builder struct {
 	blockExits        map[*ssa.BasicBlock]llvm.BasicBlock // these are the exit blocks
 	currentBlock      *ssa.BasicBlock
 	phis              []phiNode
-	taskHandle        llvm.Value
 	deferPtr          llvm.Value
 	difunc            llvm.Metadata
 	dilocals          map[*types.Var]llvm.Metadata
@@ -233,10 +229,6 @@ func Sizes(machine llvm.TargetMachine) types.Sizes {
 	targetData := machine.CreateTargetData()
 	defer targetData.Dispose()
 
-	intPtrType := targetData.IntPtrType()
-	if intPtrType.IntTypeWidth()/8 <= 32 {
-	}
-
 	var intWidth int
 	if targetData.PointerSize() <= 4 {
 		// 8, 16, 32 bits targets
@@ -251,7 +243,7 @@ func Sizes(machine llvm.TargetMachine) types.Sizes {
 	return &stdSizes{
 		IntSize:  int64(intWidth / 8),
 		PtrSize:  int64(targetData.PointerSize()),
-		MaxAlign: int64(targetData.PrefTypeAlignment(intPtrType)),
+		MaxAlign: int64(targetData.PrefTypeAlignment(targetData.IntPtrType())),
 	}
 }
 
@@ -452,7 +444,7 @@ func (c *compilerContext) createDIType(typ types.Type) llvm.Metadata {
 			AlignInBits: uint32(c.targetData.ABITypeAlignment(llvmType)) * 8,
 			ElementType: c.getDIType(typ.Elem()),
 			Subscripts: []llvm.DISubrange{
-				llvm.DISubrange{
+				{
 					Lo:    0,
 					Count: typ.Len(),
 				},