[Qemu-devel] [Bug 1824528] Re: qemu fails to compile on gcc 9 `error: taking address of packed member of ‘struct <anonymous>’ may result in an unaligned pointer value [-Werror=address-of-packed-member]`

[Satheesh Rajendran]

Tried to patch as below and it compiles fine, not sure if this is right
fix though,


# git diff
diff --git a/hw/usb/dev-mtp.c b/hw/usb/dev-mtp.c
index ebf210f..7d512e5 100644
--- a/hw/usb/dev-mtp.c
+++ b/hw/usb/dev-mtp.c
@@ -231,7 +231,7 @@ typedef struct {
     char date_modified[0]; /*unused*/
     char keywords[0]; /*unused*/
     /* string and other data follows */
-} QEMU_PACKED ObjectInfo;
+} ObjectInfo;
 
 #define TYPE_USB_MTP "usb-mtp"
 #define USB_MTP(obj) OBJECT_CHECK(MTPState, (obj), TYPE_USB_MTP)

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https://bugs.launchpad.net/bugs/1824528

Title:
  qemu fails to compile on gcc 9 `error: taking address of packed member
  of ‘struct <anonymous>’ may result in an unaligned pointer value
  [-Werror=address-of-packed-member]`

Status in QEMU:
  New

Bug description:
  Qemu compilation fails with below error on ppc64le host with gcc 9(9.0.1 
20190328)
  repo: https://github.com/qemu/qemu.git
  branch: master
  commit e1be98540ee672ef93292b65a986055512237c35

  
    CC      net/dump.o
  hw/usb/dev-mtp.c: In function ‘usb_mtp_write_metadata’:
  hw/usb/dev-mtp.c:1708:36: error: taking address of packed member of ‘struct 
<anonymous>’ may result in an unaligned pointer value 
[-Werror=address-of-packed-member]
   1708 |                             dataset->filename);
        |                             ~~~~~~~^~~~~~~~~~
  cc1: all warnings being treated as errors
    CC      net/eth.o
  make: *** [/home/kvmci/qemu-main/rules.mak:69: hw/usb/dev-mtp.o] Error 1
  make: *** Waiting for unfinished jobs....
    CC      net/announce.o

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