genbindings: prevent using qt6 qsharedmemory on android

cmd/genbindings/config-allowlist.go

@@ -105,6 +105,35 @@ func Widgets_AllowHeader(fullpath string) bool {
 	return true
 }
 
+type AllowedPlatformInfo interface {
+	GoBuildTag() string
+	CxxIf() string
+}
+
+type AndroidBlockedPlatform struct{}
+
+func (abp AndroidBlockedPlatform) GoBuildTag() string {
+	return `!android`
+}
+
+func (abp AndroidBlockedPlatform) CxxIf() string {
+	return `! defined(Q_OS_ANDROID)`
+}
+
+func HeaderPlatformRestriction(fullpath string) AllowedPlatformInfo {
+	fname := filepath.Base(fullpath)
+
+	if fname == `qsharedmemory.h` {
+		// Not implemented on Android nor iOS
+		// Qt 5: Classes are present but do not work
+		// Qt 6: Class definition is not present and our generated subclass fails to compile
+		return AndroidBlockedPlatform{}
+	}
+
+	// No platform restriction
+	return nil
+}
+
 func ImportHeaderForClass(className string) bool {
 	if className[0] != 'Q' {
 		return false

cmd/genbindings/emitcabi.go

@@ -931,6 +931,16 @@ func emitBindingCpp(src *CppParsedHeader, filename string) (string, error) {
 	ret.WriteString(`#include <` + filename + ">\n")
 	ret.WriteString(`#include "gen_` + filename + "\"\n")
 
+	// Perform any platform checks
+	// n.b. The Q_OS_ variable is defined usually indirectly from another Qt
+	// header, so it should be checked only after all the other includes,
+	// although that seems suboptimal
+
+	platformRestriction := HeaderPlatformRestriction(filename)
+	if platformRestriction != nil {
+		ret.WriteString(`#if ` + platformRestriction.CxxIf() + "\n\n")
+	}
+
 	// Write prototypes for functions that the host language bindings should export
 	// for virtual function overrides
 
@@ -1410,5 +1420,11 @@ extern "C" {
 		}
 	}
 
+	//
+
+	if platformRestriction != nil {
+		ret.WriteString(`#endif //` + platformRestriction.CxxIf() + "\n\n")
+	}
+
 	return ret.String(), nil
 }

cmd/genbindings/emitgo.go

@@ -669,6 +669,13 @@ func (gfs *goFileState) emitCabiToGo(assignExpr string, rt CppParameter, rvalue
 func emitGo(src *CppParsedHeader, headerName string, packageName string) (string, string, error) {
 
 	ret := strings.Builder{}
+
+	platformRestriction := HeaderPlatformRestriction(headerName)
+	if platformRestriction != nil {
+		ret.WriteString(`//go:build ` + platformRestriction.GoBuildTag() + "\n" +
+			`// +build ` + platformRestriction.GoBuildTag() + "\n\n")
+	}
+
 	ret.WriteString(`package ` + path.Base(packageName) + `
 
 /*