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<?xml version="1.0" encoding="utf-8" ?>
<!DOCTYPE chapter SYSTEM "chapter.dtd">
<chapter>
<header>
<copyright>
<year>2006</year><year>2013</year>
<holder>Ericsson AB. All Rights Reserved.</holder>
</copyright>
<legalnotice>
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
</legalnotice>
<title>Compiler Release Notes History</title>
<prepared>otp_appnotes</prepared>
<docno>nil</docno>
<date>nil</date>
<rev>nil</rev>
</header>
<section>
<title>Compiler 4.3</title>
<section>
<title>Fixed Bugs and Malfunctions</title>
<list type="bulleted">
<item>
<p>The semantics for boolean operators in guards have
been changed to be more consistent.</p>
<p>All boolean operators will fail if given non-boolean
arguments; '<c><![CDATA[true or garbage]]></c>' used to succeed but
will now fail. Also, failure in the evaluation of
the operands will also cause the guard to fail;
'<c><![CDATA[true or element(1, [])]]></c>' used to succeed but will
now fail.</p>
<p>Semicolon will behave as it used to. If a failure as
described above occurs, evaluation will continue with
the right operand of the semicolon.</p>
<p>*** POTENTIAL INCOMPATIBILITY ***</p>
<p>Own Id: OTP-4623</p>
</item>
<item>
<p><c><![CDATA[-compile(...)]]></c> attributes inside an Erlang module
can now contain compiler options that control warnings
(such as <c><![CDATA[warn_unused_vars]]></c>). They used to be ignored.</p>
<p>Own Id: OTP-4911</p>
</item>
<item>
<p>When a record was updated, and the record given as an
expression (such as function call), the record could be
evaluated more than once.</p>
<p>Own Id: OTP-4933</p>
</item>
<item>
<p>Compilation of modules with long strings could be
extremely slow.</p>
<p>Own Id: OTP-4960 Aux Id: seq8310 </p>
</item>
<item>
<p>In bit syntax matching with clauses having guards,
sometimes the following clauses would never match if a
guard was evaluated (and failed).</p>
<p>Own Id: OTP-4961 Aux Id: seq8338, OTP-4891 </p>
</item>
<item>
<p>Using multiple matching ('=') in the pattern for a
generator in list comprehension would cause an internal
compiler error.</p>
<p>Example:</p>
<code type="none"><![CDATA[
[3 || {3=4} <- []].
]]></code>
<p>Own Id: OTP-5076 Aux Id: OTP-5092 </p>
</item>
<item>
<p>List and string literals, and integer and character
literals were not equivalent in matching as they should
be. For instance, <c><![CDATA[f("a"=[$a])]]></c> would never match.</p>
<p>Own Id: OTP-5092 Aux Id: OTP-5076 </p>
</item>
</list>
</section>
<section>
<title>Improvements and New Features</title>
<list type="bulleted">
<item>
<p>The compiler used to warn for definition of functions
having the same name as an auto-imported BIF (such as
<c><![CDATA[size/1]]></c>). In the R10B release, such warnings will
only be emitted if the function is NOT exported (because it
will be impossible to call it). Instead, there will be a
warning for any local call (call without module prefix)
to any (exported) function in the same module that is
also the name of an auto-imported BIF. To avoid the
warning, insert a module prefix (either <c><![CDATA[erlang]]></c> to
call the BIF, or the name of the module to call function in
the module).</p>
<p>Own Id: OTP-4909</p>
</item>
<item>
<p>The unary '+' operator has been changed to throw an
<c><![CDATA[badarith]]></c> exception if its argument is not numeric (or
fail in a guard). It used its argument unchanged whatever
the type. Given the new meaning, unary '+' can now be
used to test whether a term is numeric.</p>
<p>*** POTENTIAL INCOMPATIBILITY ***</p>
<p>Own Id: OTP-4928</p>
</item>
<item>
<p>The compiler now warns for more types of suspect code,
such as expressions that will fail at run-time (such as
<c><![CDATA[atom-42]]></c>), guards that are always false, or
patterns that cannot match.</p>
<p>Own Id: OTP-5098 Aux Id: seq8965, OTP-2456 </p>
</item>
<item>
<p>The long-awaited <c><![CDATA[try]]></c>...<c><![CDATA[catch]]></c> construction
is included in this release. See the reference manual
for how to use it.</p>
<p>Own Id: OTP-5150</p>
</item>
</list>
</section>
</section>
<section>
<title>Compiler 4.2.3</title>
<section>
<title>Fixed Bugs and Malfunctions</title>
<list type="bulleted">
<item>
<p>The compiler could generate incorrect code for receive
clauses did not use the message in any way, for instance
if a guard would ignore message depending on some
condition not based on the contents of the message (e.g.
a state variable in the "loop data").</p>
<p>Own Id: OTP-5050</p>
</item>
</list>
</section>
</section>
<section>
<title>Compiler 4.2.2</title>
<section>
<title>Fixed Bugs and Malfunctions</title>
<list type="bulleted">
<item>
<p>Compilation of modules with long strings could be
extremely slow.</p>
<p>Own Id: OTP-4960 Aux Id: seq8310 </p>
</item>
<item>
<p>In bit syntax matching with clauses having guards,
sometimes the following clauses would never match if a
guard was evaluated (and failed).</p>
<p>Own Id: OTP-4961 Aux Id: seq8338, OTP-4891 </p>
</item>
<item>
<p>In <c><![CDATA[(Expr)#rec{a=A,b=B}]]></c>, <c><![CDATA[Expr]]></c> would be
evaluated more than once.</p>
<p>Own Id: OTP-4962 Aux Id: seq8292 </p>
</item>
</list>
</section>
</section>
<section>
<title>Compiler 4.2.1</title>
<section>
<title>Improvements and New Features</title>
<list type="bulleted">
<item>
<p>In rare circumstances, the compiler could optimize away
test that would verify that a tuple or record argument
indeed was of the correct type (resulting in an emulator
crash if the argument was not of the correct type/size).
Wrong code could also be generated for floating point
expressions.</p>
<p>Own Id: OTP-4790</p>
</item>
</list>
</section>
</section>
</chapter>
|
