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This section contains some additional useful notes on the operation
of the gnatmake command.
gnatmake finds no ALI files, it recompiles the main program
and all other units required by the main program.
This means that gnatmake
can be used for the initial compile, as well as during subsequent steps of
the development cycle.
gnatmake file.adb, where file.adb
is a subunit or body of a generic unit, gnatmake recompiles
file.adb (because it finds no ALI) and stops, issuing a
warning.
gnatmake the switch -I
is used to specify both source and
library file paths. Use -aI
instead if you just want to specify
source paths only and -aO
if you want to specify library paths
only.
gnatmake examines both an ALI file and its corresponding object file
for consistency. If an ALI is more recent than its corresponding object,
or if the object file is missing, the corresponding source will be recompiled.
Note that gnatmake expects an ALI and the corresponding object file
to be in the same directory.
gnatmake will ignore any files whose ALI file is write-protected.
This may conveniently be used to exclude standard libraries from
consideration and in particular it means that the use of the
-f switch will not recompile these files
unless -a is also specified.
gnatmake has been designed to make the use of Ada libraries
particularly convenient. Assume you have an Ada library organized
as follows: obj-dir contains the objects and ALI files for
of your Ada compilation units,
whereas include-dir contains the
specs of these units, but no bodies. Then to compile a unit
stored in main.adb, which uses this Ada library you would just type
$ gnatmake -aIinclude-dir -aLobj-dir main
gnatmake along with the
-m (minimal recompilation)
switch provides a mechanism for avoiding unnecessary rcompilations. Using
this switch,
you can update the comments/format of your
source files without having to recompile everything. Note, however, that
adding or deleting lines in a source files may render its debugging
info obsolete. If the file in question is a spec, the impact is rather
limited, as that debugging info will only be useful during the
elaboration phase of your program. For bodies the impact can be more
significant. In all events, your debugger will warn you if a source file
is more recent than the corresponding object, and alert you to the fact
that the debugging information may be out of date.