genbindings: move all large int constants to a 64-bit only build file

cmd/genbindings/emitgo.go

@@ -5,8 +5,10 @@ import (
 	"fmt"
 	"go/format"
 	"log"
+	"math"
 	"path"
 	"sort"
+	"strconv"
 	"strings"
 )
 
@@ -643,7 +645,7 @@ func (gfs *goFileState) emitCabiToGo(assignExpr string, rt CppParameter, rvalue
 
 }
 
-func emitGo(src *CppParsedHeader, headerName string, packageName string) (string, error) {
+func emitGo(src *CppParsedHeader, headerName string, packageName string) (string, string, error) {
 
 	ret := strings.Builder{}
 	ret.WriteString(`package ` + path.Base(packageName) + `
@@ -664,6 +666,8 @@ import "C"
 		currentPackageName: packageName,
 	}
 
+	var bigints []string
+
 	// Check if short-named enums are allowed.
 	// We only allow short names if there are no conflicts anywhere in the whole
 	// file. This doesn't fully defend against cross-file conflicts but those
@@ -716,13 +720,41 @@ import "C"
 
 		if len(e.Entries) > 0 {
 
-			ret.WriteString("const (\n")
+			var smallvalues []string
 
 			for _, ee := range e.Entries {
-				ret.WriteString(titleCase(cabiClassName(goEnumShortName+"::"+ee.EntryName)) + " " + goEnumName + " = " + ee.EntryValue + "\n")
+
+				isBigInt := false
+
+				if e.UnderlyingType.IntType() {
+					// Int-type enums need special handling in case of 64-bit
+					// overflow, that would prevent using miqt on 32-bit platforms
+
+					entryValueI64, err := strconv.ParseInt(ee.EntryValue, 10, 64)
+					if err != nil {
+						panic("Enum " + ee.EntryName + " has non-parseable integer value")
+					}
+
+					if entryValueI64 > math.MaxInt32 || entryValueI64 < math.MinInt32 {
+						isBigInt = true
+					}
+				}
+
+				enumConstDeclaration := titleCase(cabiClassName(goEnumShortName+"::"+ee.EntryName)) + " " + goEnumName + " = " + ee.EntryValue
+
+				if isBigInt {
+					bigints = append(bigints, "const "+enumConstDeclaration+"\n")
+				} else {
+					smallvalues = append(smallvalues, enumConstDeclaration+"\n")
+				}
+			}
+
+			if len(smallvalues) > 0 {
+				ret.WriteString("const (\n")
+				ret.WriteString(strings.Join(smallvalues, ""))
+				ret.WriteString("\n)\n\n")
 			}
 
-			ret.WriteString("\n)\n\n")
 		}
 	}
 
@@ -1085,5 +1117,14 @@ import "C"
 		formattedSrc = []byte(goSrc)
 	}
 
-	return string(formattedSrc), nil
+	// Determine if we need to produce a _64bit.go file
+	bigintSrc := ""
+	if len(bigints) > 0 {
+		bigintSrc = `//go:build !386 && !arm
+// +build !386,!arm
+
+package ` + path.Base(packageName) + "\n\n" + strings.Join(bigints, "") + "\n"
+	}
+
+	return string(formattedSrc), bigintSrc, nil
 }

cmd/genbindings/main.go

@@ -222,7 +222,7 @@ func generate(packageName string, srcDirs []string, allowHeaderFn func(string) b
 			counter++
 		}
 
-		goSrc, err := emitGo(parsed, filepath.Base(parsed.Filename), packageName)
+		goSrc, go64Src, err := emitGo(parsed, filepath.Base(parsed.Filename), packageName)
 		if err != nil {
 			panic(err)
 		}
@@ -232,6 +232,13 @@ func generate(packageName string, srcDirs []string, allowHeaderFn func(string) b
 			panic(err)
 		}
 
+		if len(go64Src) > 0 {
+			err = os.WriteFile(outputName+"_64bit.go", []byte(go64Src), 0644)
+			if err != nil {
+				panic(err)
+			}
+		}
+
 		bindingCppSrc, err := emitBindingCpp(parsed, filepath.Base(parsed.Filename))
 		if err != nil {
 			panic(err)