passing by reference... my darkest enemy
actual reason below:
In your case (without reference) the compiler generates a temporary object (int) for the first argument of your MyApplication constructor. You pass this temporary int to QApplication’s constructor (with int reference), which saves the address of this reference. Once your MyApplication constructor is done the temporary int is destroyed but QApplication still has its address.
/***************************************************************************/
/* */
/* t1tokens.h */
/* */
/* Type 1 tokenizer (specification). */
/* */
/* Copyright 1996-2001, 2002, 2003, 2004, 2006, 2008, 2009 by */
/* David Turner, Robert Wilhelm, and Werner Lemberg. */
/* */
/* This file is part of the FreeType project, and may only be used, */
/* modified, and distributed under the terms of the FreeType project */
/* license, LICENSE.TXT. By continuing to use, modify, or distribute */
/* this file you indicate that you have read the license and */
/* understand and accept it fully. */
/* */
/***************************************************************************/
#undef FT_STRUCTURE
#define FT_STRUCTURE PS_FontInfoRec
#undef T1CODE
#define T1CODE T1_FIELD_LOCATION_FONT_INFO
T1_FIELD_STRING( "version", version,
T1_FIELD_DICT_FONTDICT )
T1_FIELD_STRING( "Notice", notice,
T1_FIELD_DICT_FONTDICT )
T1_FIELD_STRING( "FullName", full_name,
T1_FIELD_DICT_FONTDICT )
T1_FIELD_STRING( "FamilyName", family_name,
T1_FIELD_DICT_FONTDICT )
T1_FIELD_STRING( "Weight", weight,
T1_FIELD_DICT_FONTDICT )
/* we use pointers to detect modifications made by synthetic fonts */
T1_FIELD_NUM ( "ItalicAngle", italic_angle,
T1_FIELD_DICT_FONTDICT )
T1_FIELD_BOOL ( "isFixedPitch", is_fixed_pitch,
T1_FIELD_DICT_FONTDICT )
T1_FIELD_NUM ( "UnderlinePosition", underline_position,
T1_FIELD_DICT_FONTDICT )
T1_FIELD_NUM ( "UnderlineThickness", underline_thickness,
T1_FIELD_DICT_FONTDICT )
#undef FT_STRUCTURE
#define FT_STRUCTURE PS_FontExtraRec
#undef T1CODE
#define T1CODE T1_FIELD_LOCATION_FONT_EXTRA
T1_FIELD_NUM ( "FSType", fs_type,
T1_FIELD_DICT_FONTDICT )
#undef FT_STRUCTURE
#define FT_STRUCTURE PS_PrivateRec
#undef T1CODE
#define T1CODE T1_FIELD_LOCATION_PRIVATE
T1_FIELD_NUM ( "UniqueID", unique_id,
T1_FIELD_DICT_FONTDICT | T1_FIELD_DICT_PRIVATE )
T1_FIELD_NUM ( "lenIV", lenIV,
T1_FIELD_DICT_PRIVATE )
T1_FIELD_NUM ( "LanguageGroup", language_group,
T1_FIELD_DICT_PRIVATE )
T1_FIELD_NUM ( "password", password,
T1_FIELD_DICT_PRIVATE )
T1_FIELD_FIXED_1000( "BlueScale", blue_scale,
T1_FIELD_DICT_PRIVATE )
T1_FIELD_NUM ( "BlueShift", blue_shift,
T1_FIELD_DICT_PRIVATE )
T1_FIELD_NUM ( "BlueFuzz", blue_fuzz,
T1_FIELD_DICT_PRIVATE )
T1_FIELD_NUM_TABLE ( "BlueValues", blue_values, 14,
T1_FIELD_DICT_PRIVATE )
T1_FIELD_NUM_TABLE ( "OtherBlues", other_blues, 10,
T1_FIELD_DICT_PRIVATE )
T1_FIELD_NUM_TABLE ( "FamilyBlues", family_blues, 14,
T1_FIELD_DICT_PRIVATE )
T1_FIELD_NUM_TABLE ( "FamilyOtherBlues", family_other_blues, 10,
T1_FIELD_DICT_PRIVATE )
T1_FIELD_NUM_TABLE2( "StdHW", standard_width, 1,
T1_FIELD_DICT_PRIVATE )
T1_FIELD_NUM_TABLE2( "StdVW", standard_height, 1,
T1_FIELD_DICT_PRIVATE )
T1_FIELD_NUM_TABLE2( "MinFeature", min_feature, 2,
T1_FIELD_DICT_PRIVATE )
T1_FIELD_NUM_TABLE ( "StemSnapH", snap_widths, 12,
T1_FIELD_DICT_PRIVATE )
T1_FIELD_NUM_TABLE ( "StemSnapV", snap_heights, 12,
T1_FIELD_DICT_PRIVATE )
T1_FIELD_FIXED ( "ExpansionFactor", expansion_factor,
T1_FIELD_DICT_PRIVATE )
T1_FIELD_BOOL ( "ForceBold", force_bold,
T1_FIELD_DICT_PRIVATE )
#undef FT_STRUCTURE
#define FT_STRUCTURE T1_FontRec
#undef T1CODE
#define T1CODE T1_FIELD_LOCATION_FONT_DICT
T1_FIELD_KEY ( "FontName", font_name, T1_FIELD_DICT_FONTDICT )
T1_FIELD_NUM ( "PaintType", paint_type, T1_FIELD_DICT_FONTDICT )
T1_FIELD_NUM ( "FontType", font_type, T1_FIELD_DICT_FONTDICT )
T1_FIELD_FIXED( "StrokeWidth", stroke_width, T1_FIELD_DICT_FONTDICT )
#undef FT_STRUCTURE
#define FT_STRUCTURE FT_BBox
#undef T1CODE
#define T1CODE T1_FIELD_LOCATION_BBOX
T1_FIELD_BBOX( "FontBBox", xMin, T1_FIELD_DICT_FONTDICT )
#ifndef T1_CONFIG_OPTION_NO_MM_SUPPORT
#undef FT_STRUCTURE
#define FT_STRUCTURE T1_FaceRec
#undef T1CODE
#define T1CODE T1_FIELD_LOCATION_FACE
T1_FIELD_NUM( "NDV", ndv_idx, T1_FIELD_DICT_PRIVATE )
T1_FIELD_NUM( "CDV", cdv_idx, T1_FIELD_DICT_PRIVATE )
#undef FT_STRUCTURE
#define FT_STRUCTURE PS_BlendRec
#undef T1CODE
#define T1CODE T1_FIELD_LOCATION_BLEND
T1_FIELD_NUM_TABLE( "DesignVector", default_design_vector,
T1_MAX_MM_DESIGNS, T1_FIELD_DICT_FONTDICT )
#endif /* T1_CONFIG_OPTION_NO_MM_SUPPORT */
/* END */