https://bugs.gentoo.org/871087
--- a/m4/id3_cxx.m4
+++ b/m4/id3_cxx.m4
@@ -81,7 +81,7 @@ AC_DEFUN(ID3_CXX_PORTABILITY,[
 
   dnl Check whether we have bool
   AC_MSG_CHECKING(whether C++ has bool)
-  AC_TRY_RUN([main() { bool b1=true; bool b2=false; }],
+  AC_TRY_RUN([int main() { bool b1=true; bool b2=false; }],
              [ AC_MSG_RESULT(yes) ],
              [ AC_MSG_RESULT(no)
                AC_DEFINE(CXX_HAS_NO_BOOL) ],
@@ -90,7 +90,7 @@ AC_DEFUN(ID3_CXX_PORTABILITY,[
 
   dnl Test whether C++ has buggy for-loops
   AC_MSG_CHECKING(whether C++ has correct scoping in for-loops)
-  AC_TRY_COMPILE([#include <iostream.h>], [
+  AC_TRY_COMPILE([#include <iostream>], [
    for (int i=0;i<10;i++) { }
    for (int i=0;i<10;i++) { }
 ], [ AC_MSG_RESULT(yes) ],