invoke.texi (-fshort-wchar): Move to Code Generation Options.

2002-09-04  Janis Johnson  <janis187@us.ibm.com>

	* doc/invoke.texi (-fshort-wchar): Move to Code Generation Options.
	(-fpcc-struct-return, -freg-struct-return, -fshort-enums,
	-fshort-double, -fshort-wchar, -fpack-struct, -fleading-underscore):
	Warn that these options can break ABI compatibility.

From-SVN: r56799

gcc/ChangeLog

+2002-09-04  Janis Johnson  <janis187@us.ibm.com>
+
+	* doc/invoke.texi (-fshort-wchar): Move to Code Generation Options.
+	(-fpcc-struct-return, -freg-struct-return, -fshort-enums,
+	-fshort-double, -fshort-wchar, -fpack-struct, -fleading-underscore):
+	Warn that these options can break ABI compatibility.
+
 2002-09-04  Richard Henderson  <rth@redhat.com>
 
 	* real.c (ereal_to_decimal): Add digits parameter.

gcc/doc/invoke.texi

@@ -169,7 +169,7 @@ in the following sections.
 -fallow-single-precision  -fcond-mismatch @gol
 -fsigned-bitfields  -fsigned-char @gol
 -funsigned-bitfields  -funsigned-char @gol
--fwritable-strings  -fshort-wchar}
+-fwritable-strings}
 
 @item C++ Language Options
 @xref{C++ Dialect Options,,Options Controlling C++ Dialect}.
@@ -679,7 +679,7 @@ in the following sections.
 -fno-common  -fno-ident  -fno-gnu-linker @gol
 -fpcc-struct-return  -fpic  -fPIC @gol
 -freg-struct-return  -fshared-data  -fshort-enums @gol
--fshort-double  -fvolatile @gol
+-fshort-double  -fshort-wchar -fvolatile @gol
 -fvolatile-global  -fvolatile-static @gol
 -fverbose-asm  -fpack-struct  -fstack-check @gol
 -fstack-limit-register=@var{reg}  -fstack-limit-symbol=@var{sym} @gol
@@ -1221,12 +1221,6 @@ write into string constants.
 
 Writing into string constants is a very bad idea; ``constants'' should
 be constant.
-
-@item -fshort-wchar
-@opindex fshort-wchar
-Override the underlying type for @samp{wchar_t} to be @samp{short
-unsigned int} instead of the default for the target.  This option is
-useful for building programs to run under WINE@.
 @end table
 
 @node C++ Dialect Options
@@ -9893,7 +9887,8 @@ unwinding from asynchronous events (such as debugger or garbage collector).
 Return ``short'' @code{struct} and @code{union} values in memory like
 longer ones, rather than in registers.  This convention is less
 efficient, but it has the advantage of allowing intercallability between
-GCC-compiled files and files compiled with other compilers.
+GCC-compiled files and files compiled with other compilers, particularly
+the Portable C Compiler (pcc).
 
 The precise convention for returning structures in memory depends
 on the target configuration macros.
@@ -9901,6 +9896,11 @@ on the target configuration macros.
 Short structures and unions are those whose size and alignment match
 that of some integer type.
 
+@strong{Warning:} code compiled with the @option{-fpcc-struct-return}
+switch is not binary compatible with code compiled with the
+@option{-freg-struct-return} switch.
+Use it to conform to a non-default application binary interface.
+
 @item -freg-struct-return
 @opindex freg-struct-return
 Return @code{struct} and @code{union} values in registers when possible.
@@ -9914,16 +9914,39 @@ defaults to @option{-fpcc-struct-return}, except on targets where GCC is
 the principal compiler.  In those cases, we can choose the standard, and
 we chose the more efficient register return alternative.
 
+@strong{Warning:} code compiled with the @option{-freg-struct-return}
+switch is not binary compatible with code compiled with the
+@option{-fpcc-struct-return} switch.
+Use it to conform to a non-default application binary interface.
+
 @item -fshort-enums
 @opindex fshort-enums
 Allocate to an @code{enum} type only as many bytes as it needs for the
 declared range of possible values.  Specifically, the @code{enum} type
 will be equivalent to the smallest integer type which has enough room.
 
+@strong{Warning:} the @option{-fshort-enums} switch causes GCC to generate
+code that is not binary compatible with code generated without that switch.
+Use it to conform to a non-default application binary interface.
+
 @item -fshort-double
 @opindex fshort-double
 Use the same size for @code{double} as for @code{float}.
 
+@strong{Warning:} the @option{-fshort-double} switch causes GCC to generate
+code that is not binary compatible with code generated without that switch.
+Use it to conform to a non-default application binary interface.
+
+@item -fshort-wchar
+@opindex fshort-wchar
+Override the underlying type for @samp{wchar_t} to be @samp{short
+unsigned int} instead of the default for the target.  This option is
+useful for building programs to run under WINE@.
+
+@strong{Warning:} the @option{-fshort-wchar} switch causes GCC to generate
+code that is not binary compatible with code generated without that switch.
+Use it to conform to a non-default application binary interface.
+
 @item -fshared-data
 @opindex fshared-data
 Requests that the data and non-@code{const} variables of this
@@ -10065,9 +10088,12 @@ three-way choice.
 
 @item -fpack-struct
 @opindex fpack-struct
-Pack all structure members together without holes.  Usually you would
-not want to use this option, since it makes the code suboptimal, and
-the offsets of structure members won't agree with system libraries.
+Pack all structure members together without holes.
+
+@strong{Warning:} the @option{-fpack-struct} switch causes GCC to generate
+code that is not binary compatible with code generated without that switch.
+Additionally, it makes the code suboptimial.
+Use it to conform to a non-default application binary interface.
 
 @item -finstrument-functions
 @opindex finstrument-functions
@@ -10164,8 +10190,10 @@ This option and its counterpart, @option{-fno-leading-underscore}, forcibly
 change the way C symbols are represented in the object file.  One use
 is to help link with legacy assembly code.
 
-Be warned that you should know what you are doing when invoking this
-option, and that not all targets provide complete support for it.
+@strong{Warning:} the @option{-fleading-underscore} switch causes GCC to
+generate code that is not binary compatible with code generated without that
+switch.  Use it to conform to a non-default application binary interface.
+Not all targets provide complete support for this switch.
 
 @item -ftls-model=@var{model}
 Alter the thread-local storage model to be used (@pxref{Thread-Local}).