fix cgo array to slice casting

Instead of using a type of array of size 1 << 30, manipulate fields of slice
header.

Fix error on i686-w64-mingw32:
compile.go:407:30: type [1073741824]*_Ctype_char larger than address space

internal/ch/compile.go

@@ -129,6 +129,16 @@ func CompileMulti(p Patterns, mode CompileMode, info *hs.PlatformInfo) (Database
 	return CompileExtMulti(p, mode, info, 0, 0)
 }
 
+func castCArrayToSlice[T any](c *T, count int) []T {
+	var list []T
+	sliceHeader := (*reflect.SliceHeader)((unsafe.Pointer(&list)))
+	sliceHeader.Cap = count
+	sliceHeader.Len = count
+	sliceHeader.Data = uintptr(unsafe.Pointer(c))
+
+	return list
+}
+
 // The multiple regular expression compiler.
 func CompileExtMulti(p Patterns, mode CompileMode, info *hs.PlatformInfo,
 	matchLimit, matchLimitRecursion uint,
@@ -144,13 +154,13 @@ func CompileExtMulti(p Patterns, mode CompileMode, info *hs.PlatformInfo,
 	patterns := p.Patterns()
 
 	cexprs := (**C.char)(C.calloc(C.size_t(len(patterns)), C.size_t(unsafe.Sizeof(uintptr(0)))))
-	exprs := (*[1 << 30]*C.char)(unsafe.Pointer(cexprs))[:len(patterns):len(patterns)]
+	exprs := castCArrayToSlice[*C.char](cexprs, len(patterns))
 
 	cflags := (*C.uint)(C.calloc(C.size_t(len(patterns)), C.size_t(unsafe.Sizeof(C.uint(0)))))
-	flags := (*[1 << 30]C.uint)(unsafe.Pointer(cflags))[:len(patterns):len(patterns)]
+	flags := castCArrayToSlice[C.uint](cflags, len(patterns))
 
 	cids := (*C.uint)(C.calloc(C.size_t(len(patterns)), C.size_t(unsafe.Sizeof(C.uint(0)))))
-	ids := (*[1 << 30]C.uint)(unsafe.Pointer(cids))[:len(patterns):len(patterns)]
+	ids := castCArrayToSlice[C.uint](cids, len(patterns))
 
 	for i, pattern := range patterns {
 		exprs[i] = C.CString(pattern.Expression)

internal/hs/compile.go

@@ -10,6 +10,7 @@ import "C"
 import (
 	"errors"
 	"fmt"
+	"reflect"
 	"runtime"
 	"sort"
 	"strings"
@@ -391,6 +392,16 @@ type Patterns interface {
 	Patterns() []*Pattern
 }
 
+func castCArrayToSlice[T any](c *T, count int) []T {
+	var list []T
+	sliceHeader := (*reflect.SliceHeader)((unsafe.Pointer(&list)))
+	sliceHeader.Cap = count
+	sliceHeader.Len = count
+	sliceHeader.Data = uintptr(unsafe.Pointer(c))
+
+	return list
+}
+
 func CompileMulti(input Patterns, mode ModeFlag, info *PlatformInfo) (Database, error) {
 	var db *C.hs_database_t
 	var err *C.hs_compile_error_t
@@ -404,16 +415,16 @@ func CompileMulti(input Patterns, mode ModeFlag, info *PlatformInfo) (Database,
 	count := len(patterns)
 
 	cexprs := (**C.char)(C.calloc(C.size_t(count), C.size_t(unsafe.Sizeof(uintptr(0)))))
-	exprs := (*[1 << 30]*C.char)(unsafe.Pointer(cexprs))[:count:count]
+	exprs := castCArrayToSlice[*C.char](cexprs, count)
 
 	cflags := (*C.uint)(C.calloc(C.size_t(count), C.size_t(unsafe.Sizeof(C.uint(0)))))
-	flags := (*[1 << 30]C.uint)(unsafe.Pointer(cflags))[:count:count]
+	flags := castCArrayToSlice[C.uint](cflags, count)
 
 	cids := (*C.uint)(C.calloc(C.size_t(count), C.size_t(unsafe.Sizeof(C.uint(0)))))
-	ids := (*[1 << 30]C.uint)(unsafe.Pointer(cids))[:count:count]
+	ids := castCArrayToSlice[C.uint](cids, count)
 
 	cexts := (**C.hs_expr_ext_t)(C.calloc(C.size_t(count), C.size_t(unsafe.Sizeof(uintptr(0)))))
-	exts := (*[1 << 30]*C.hs_expr_ext_t)(unsafe.Pointer(cexts))[:count:count]
+	exts := castCArrayToSlice[*C.hs_expr_ext_t](cexts, count)
 
 	for i, pattern := range patterns {
 		exprs[i] = C.CString(pattern.Expr)

internal/hs/compile_v52.go

@@ -71,16 +71,16 @@ func CompileLitMulti(input Literals, mode ModeFlag, info *PlatformInfo) (Databas
 	count := len(literals)
 
 	cexprs := (**C.char)(C.calloc(C.size_t(len(literals)), C.size_t(unsafe.Sizeof(uintptr(0)))))
-	exprs := (*[1 << 30]*C.char)(unsafe.Pointer(cexprs))[:len(literals):len(literals)]
+	exprs := castCArrayToSlice[*C.char](cexprs, len(literals))
 
 	clens := (*C.size_t)(C.calloc(C.size_t(len(literals)), C.size_t(unsafe.Sizeof(uintptr(0)))))
-	lens := (*[1 << 30]C.size_t)(unsafe.Pointer(clens))[:len(literals):len(literals)]
+	lens := castCArrayToSlice[C.size_t](clens, len(literals))
 
 	cflags := (*C.uint)(C.calloc(C.size_t(len(literals)), C.size_t(unsafe.Sizeof(C.uint(0)))))
-	flags := (*[1 << 30]C.uint)(unsafe.Pointer(cflags))[:len(literals):len(literals)]
+	flags := castCArrayToSlice[C.uint](cflags, len(literals))
 
 	cids := (*C.uint)(C.calloc(C.size_t(len(literals)), C.size_t(unsafe.Sizeof(C.uint(0)))))
-	ids := (*[1 << 30]C.uint)(unsafe.Pointer(cids))[:len(literals):len(literals)]
+	ids := castCArrayToSlice[C.uint](cids, len(literals))
 
 	for i, lit := range literals {
 		exprs[i] = C.CString(lit.Expr)