20062013 Ericsson AB. All Rights Reserved. The contents of this file are subject to the Erlang Public License, Version 1.1, (the "License"); you may not use this file except in compliance with the License. You should have received a copy of the Erlang Public License along with this software. If not, it can be retrieved online at http://www.erlang.org/. Software distributed under the License is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License for the specific language governing rights and limitations under the License. Compiler Release Notes History otp_appnotes nil nil nil
Compiler 4.3
Fixed Bugs and Malfunctions

The semantics for boolean operators in guards have been changed to be more consistent.

All boolean operators will fail if given non-boolean arguments; '' used to succeed but will now fail. Also, failure in the evaluation of the operands will also cause the guard to fail; '' used to succeed but will now fail.

Semicolon will behave as it used to. If a failure as described above occurs, evaluation will continue with the right operand of the semicolon.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-4623

attributes inside an Erlang module can now contain compiler options that control warnings (such as ). They used to be ignored.

Own Id: OTP-4911

When a record was updated, and the record given as an expression (such as function call), the record could be evaluated more than once.

Own Id: OTP-4933

Compilation of modules with long strings could be extremely slow.

Own Id: OTP-4960 Aux Id: seq8310

In bit syntax matching with clauses having guards, sometimes the following clauses would never match if a guard was evaluated (and failed).

Own Id: OTP-4961 Aux Id: seq8338, OTP-4891

Using multiple matching ('=') in the pattern for a generator in list comprehension would cause an internal compiler error.

Example:

Own Id: OTP-5076 Aux Id: OTP-5092

List and string literals, and integer and character literals were not equivalent in matching as they should be. For instance, would never match.

Own Id: OTP-5092 Aux Id: OTP-5076

Improvements and New Features

The compiler used to warn for definition of functions having the same name as an auto-imported BIF (such as ). 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 to call the BIF, or the name of the module to call function in the module).

Own Id: OTP-4909

The unary '+' operator has been changed to throw an 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.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-4928

The compiler now warns for more types of suspect code, such as expressions that will fail at run-time (such as ), guards that are always false, or patterns that cannot match.

Own Id: OTP-5098 Aux Id: seq8965, OTP-2456

The long-awaited ... construction is included in this release. See the reference manual for how to use it.

Own Id: OTP-5150
Compiler 4.2.3
Fixed Bugs and Malfunctions

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").

Own Id: OTP-5050
Compiler 4.2.2
Fixed Bugs and Malfunctions

Compilation of modules with long strings could be extremely slow.

Own Id: OTP-4960 Aux Id: seq8310

In bit syntax matching with clauses having guards, sometimes the following clauses would never match if a guard was evaluated (and failed).

Own Id: OTP-4961 Aux Id: seq8338, OTP-4891

In , would be evaluated more than once.

Own Id: OTP-4962 Aux Id: seq8292

Compiler 4.2.1
Improvements and New Features

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.

Own Id: OTP-4790