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187 lines
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HTML
Executable file
187 lines
11 KiB
HTML
Executable file
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
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<html>
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<head>
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<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
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<title>Inform Release Notes</title>
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</head>
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<body>
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<h1>Inform 6.4 Release Notes</h1>
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<h2>Introduction</h2>
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This is a maintenance release of the Inform 6 compiler for creating interactive fiction. Although just about
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all known bugs are fixed, the approach to enhancing Inform is more conservative. The selection of suggestions
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to implement has been governed by two factors:
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<ul>
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<li><p>Avoidance of changes which might cause existing games to misbehave; and
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<li><p>Minimisation of features which would require updates to the <i>Inform Designer’s Manual</i>.
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</ul>
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Since the first release of the Inform 6.3 compiler, the Inform 6 library has been split into a separate project,
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maintained at <a href="https://gitlab.com/DavidGriffith/inform6lib">https://gitlab.com/DavidGriffith/inform6lib</a>.
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<h2>Acknowledgements</h2>
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Far too many people contributed towards this release — reporting and resolving bugs, making helpful
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suggestions, providing support and facilities, testing, and so on — for their names to be individually
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listed. So instead, this is a general thank-you to everybody who has made this release happen, and
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specific ones to Graham Nelson for permitting it in the first place, and to Andrew Plotkin, who is responsible
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for most of the actual changes to the compiler code.
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<h2>Inform 6.41</h2>
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These are the changes delivered in version 6.41 of the Inform compiler.
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<h3>Features added</h3>
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<ul>
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<li><p>The dead code elimination logic now allows forward jumps to labels that would be otherwise unreachable, like this:
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<pre>
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if (condition) {
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jump MiddleLabel;
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}
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if (0) {
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while (condition) {
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...
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.MiddleLabel;
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...
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}
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}
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</pre>
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<li><p>The error that occurs when the compiler encounters a jump to an unknown label now includes the name of that label.
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</ul>
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<h2>Inform 6.40</h2>
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These are the changes delivered in version 6.40 of the Inform compiler.
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<h3>Features added</h3>
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<ul>
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<li><p>The various command line arguments that produce tracing or statistical information have been consolidated in a new
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argument: <tt>$!TRACEOPT</tt> or <tt>$!TRACEOPT=N</tt>. The Unix-style equivalent is <tt>--trace TRACEOPT</tt> or
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<tt>--trace TRACEOPT=N</tt>. You can also use <tt>$!</tt> by itself (or <tt>--helptrace</tt>) to list all available trace options.
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Trace option names are case-insensitive.
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<p>
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The optional <tt>N</tt> is always an integer. 0 always means off, 1 is the base level, 2 or more may increase verbosity.
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As a general rule, setting <tt>N</tt> to a high number is not an error; it just does the same thing as the highest supported
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number for that option. (This lets us add more verbosity levels to any option without worrying about compatibility errors.)
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<p>
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Four trace settings can be changed in mid-compile with the <tt>Trace</tt> directive. (This has always been true but now it is handled
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consistently.) <tt>Trace assembly</tt>, <tt>Trace expressions</tt>, <tt>Trace tokens</tt> and <tt>Trace linker</tt> are
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equivalent to <tt>--trace asm</tt>, <tt>--trace expr</tt>, <tt>--trace tokens</tt> and <tt>--trace linker</tt>, respectively.
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As with the command-line versions, you can optionally specify 0 to turn off that setting or 2 or more for more verbosity.
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<p>
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Four more trace directives do an immediate information dump: <tt>Trace dictionary</tt>, <tt>Trace objects</tt>,
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<tt>Trace symbols</tt> and <tt>Trace verbs</tt>. The command-line equivalents <tt>--trace dict</tt>, <tt>--trace objects</tt>,
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<tt>--trace symbols</tt> and <tt>--trace verbs</tt> do the same at the end of compilation.
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<p>
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The following single-letter options have been removed and replaced with trace options:
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<ul>
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<li><tt>-j</tt>: Replaced by <tt>--trace OBJECTS</tt>
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<li><tt>-m</tt>: Replaced by <tt>--trace MEM</tt>
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<li><tt>-n</tt>: Replaced by <tt>--trace PROPS</tt> (for property information) and <tt>--trace ACTIONS</tt> (for action numbers)
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<li><tt>-p</tt>: Replaced by <tt>--trace MAP=2</tt>
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<li><tt>-t</tt>: Replaced by <tt>--trace ASM=2</tt>
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<li><tt>-y</tt>: Replaced by <tt>--trace LINKER</tt>
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</ul><br>
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The following single-letter options still exist, but are now aliases for trace options:
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<ul><br>
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<li><tt>-a</tt>: Same as <tt>--trace ASM</tt>
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<li><tt>-f</tt>: Same as <tt>--trace FREQ</tt>
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<li><tt>-g</tt>: Same as <tt>--trace RUNTIME</tt>
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<li><tt>-s</tt>: Same as <tt>--trace STATS</tt>
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<li><tt>-z</tt>: Same as <tt>--trace MAP</tt>
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</ul><br>
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The following single-letter options have been removed entirely:
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<ul><br>
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<li><tt>-b</tt>: Has not done anything since at least Inform 5.
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<li><tt>-l</tt>: Was supposed to list all statements compiled, but it was never implemented.
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<li><tt>-o</tt>: Showed the same information as <tt>-z</tt> or <tt>--trace MAP</tt>.
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</ul><br>
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The <tt>-l</tt> option did show include files being opened; this is now a separate trace setting, <tt>--trace FILES</tt>.
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<p>
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Some of the information that used to be under <tt>-a4</tt> is now a separate trace setting, <tt>--trace BPATCH</tt>.
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<li><p>The <tt>-u</tt> option now just outputs computed abbreviations. If you want the verbose calculation information that
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it used to print, use <tt>--trace FINDABBREVS</tt> or <tt>--trace FINDABBREVS=2</tt>.
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<li><p>The compiler is now capable of dead code elimination, allowing it to:
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<ul>
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<li>Discard unreachable opcodes and strings.
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<li>Minimize generated code for dead branches (<tt>if (0)</tt>, <tt>if (1)</tt>).
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<li>Detect <tt>if</tt> and <tt>switch</tt> statements where every branch returns.
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<li>Detect loops that never exit (or always return).
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<li>Discard <tt>@jz constant</tt> opcodes where the constant is non-zero.
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<li>Convert <tt>@jz 0</tt> to an unconditional <tt>@jump</tt>.
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<li>Discard a <tt>@jump</tt> to the very next instruction.
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<li>Discard store opcodes when computing a logical expression as a value, if one case (0 or 1) is impossible.
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<li>Fold expressions like <tt>(0 && expr)</tt> and <tt>(1 || expr)</tt>, even when <tt>expr</tt> is not a constant.
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</ul><br>
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When statements that can never be reached are eliminated, a warning is produced, where appropriate.
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<p>
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Dead code elimination does mean that theoretically possible (though very odd) valid code will now
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result in a compilation error. For example,
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<pre>
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if (DOSTUFF) {
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while (condition) {
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...
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.MiddleLabel;
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...
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}
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}
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jump MiddleLabel; ! error
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</pre>
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This will fail with a compilation error if <tt>DOSTUFF</tt> is defined as a constant zero. This optimization
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can be turned off by setting the compiler setting <tt>$STRIP_UNREACHABLE_LABELS</tt> to zero (its default is one).
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<li><p>There are now further warnings if the compiler detects that the type used in certain expressions is not correct:
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<ul>
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<li><tt>X()</tt>, <tt>indirect(X)</tt>: X must be a routine
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<li><tt>X.Y</tt>, <tt>X.&Y</tt>, <tt>X.#Y</tt>: X must be a class or an object; Y must be a property (the Y checks already existed)
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<li><tt>X.Y()</tt>: X must be a class, object, string or routine; Y must be a property
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<li><tt>X.Y++</tt>, <tt>X.Y--</tt>, <tt>++X.Y</tt>, <tt>--X.Y</tt>: X must be a class or an object; Y must be a property
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</ul>
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<li><p>There is a new syntax for dynamic-string interpolations: <tt>"@(N)"</tt>. The original syntax was <tt>"@NN"</tt>,
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which is still supported. In the new syntax <tt>"N"</tt> can be a number, or an already defined numeric constant.
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As a result of this, under Glulx the limit on <tt>$MAX_DYNAMIC_STRINGS</tt> being less than 100 has been removed.
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<li><p>The constants <tt>#dictionary_table</tt> and <tt>#grammar_table</tt> are now available when compiling to
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Z-code, as well as Glulx.
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<li><p>The command line switch to display percentages (<tt>-p</tt>) now works with Glulx, and acts as an
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extension to the <tt>-z</tt> switch.
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<li><p>The double precision floating point related opcodes added to the Glulx 3.1.3 specification (that is,
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<tt>@numtod</tt>, <tt>@dtonumz</tt>, <tt>@dtonumn</tt>, <tt>@ftod</tt>, <tt>@dtof</tt>, <tt>@dceil</tt>, <tt>@dfloor</tt>,
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<tt>@dadd</tt>, <tt>@dsub</tt>, <tt>@dmul</tt>, <tt>@ddiv</tt>, <tt>@dmodr</tt>, <tt>@dmodq</tt>, <tt>@dsqrt</tt>,
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<tt>@dexp</tt>, <tt>@dlog</tt>, <tt>@dpow</tt>, <tt>@dsin</tt>, <tt>@dcos</tt>, <tt>@dtan</tt>, <tt>@dasin</tt>,
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<tt>@dacos</tt>, <tt>@datan</tt>, <tt>@datan2</tt>, <tt>@jdeq</tt>, <tt>@jdne</tt>, <tt>@jdlt</tt>, <tt>@jdle</tt>,
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<tt>@jdgt</tt>, <tt>@jdge</tt>, <tt>@jdisnan</tt>, <tt>@jdisinf</tt>) are now supported. In addition there are also
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two new macros <tt>@dload</tt> and <tt>@dstore</tt>, to load and store double precision floating point values.
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<li><p>The undo related opcodes added to the Glulx 3.1.3 specification (that is, <tt>@hasundo</tt> and <tt>@discardundo</tt>)
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are now supported.
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<li><p>The <tt>Version</tt> and <tt>Switches</tt> directives are now deprecated, and produce a warning if used. The recommended way to
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set the Z-code version and any other switches is to use the command line, or <tt>!%</tt> comments at the top of the source file.
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<li><p>The ability to compile Inform source code as modules, and then later link it, has been removed. This functionality always had
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significant restrictions and was never widely used. The <tt>-M</tt> and <tt>-U</tt> command line options have been removed, along with
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the <tt>+module_path</tt> option. The <tt>Link</tt> and <tt>Import</tt> directives now just produce errors.
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<li><p>The ability to use temporary files for internal storage (the <tt>-F</tt> switch and the <tt>+temporary_path</tt> option)
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have been removed.
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<li><p>The <tt>=</tt> sign in the <tt>Global</tt> directive is now optional, just as it is in the <tt>Constant</tt> directive. So all
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of these are now legal:
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<pre>
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Constant c1 11;
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Constant c2 = 22;
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Global g1 33;
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Global g2 = 44;
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</pre>
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<li><p>The long deprecated forms of the <tt>Global</tt> directive that could define arrays have been removed. All these are now no
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longer legal:
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<pre>
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Global array --> size;
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Global array data ...;
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Global array initial ...;
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Global array initstr ...;
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</pre>
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</ul>
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<h3>Bugs fixed</h3>
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<ul>
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<li><p><tt>Abbreviation</tt> directives now only add abbreviations to the output file if economy mode (<tt>-e</tt>) is set.
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<li><p>An array overrun when the <tt>$ZCODE_LESS_DICT_DATA</tt> setting is enabled has been fixed.
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<li><p>The logic that allows a test for the compiler version of the form <tt>#IfDef VN_1640</tt> now requires what follows
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the "VN_" to be a number.
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</ul>
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</body>
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</html>
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