## 1 Dialyzer Release Notes

This document describes the changes made to the Dialyzer application.

### 1.1 Dialyzer 2.0.0

#### 1.1.1 Improvements and New Features

- There is a major addition to the capabilities of dialyzer, worthy of bumping the version number. Starting with this version, dialyzer not only accepts but also properly processes remote types (i.e., types of the form ModuleName:TypeName()). Previous dialyzer versions only accepted this notation in -type and -spec declarations, but effectively ignored its information by mapping remote types to the type any(). In contrast, starting with this version, remote types are used in the analysis and are also stored in the PLTs. (This addition changes the format of PLTs and requires rebuilding any PLTs created by an older dialyzer version.) Note that dialyzer will complain and abort the analysis of a set of modules if it needs to process a remote type without a definition (either because the module does not include a definition of the type or the module is not included in the analysis). We may relax this restriction in a future version.
  Fixed minor issue with dialyzer:run/1 crashing (upon its return) when used for adding type information to an existing PLT.
  Fixed minor but quite annoying issues in dialyzer's GUI.
  Own Id: OTP-8187

### 1.2 Dialyzer 1.9.2

#### 1.2.1 Improvements and New Features

- Fixed problem with type inference going into an infinite loop when analyzing a strongly connected component of functions that do not return but also contain an erroneous call which makes them fail and be assigned the type none() instead of the type unit().
  More accurate type information for some BIFs and library files.
  Introduced boolean() as the `official' name for the type was so far known as bool(). The latter is still accepted as well as boolean().
  Own Id: OTP-8037

### 1.3 Dialyzer 1.9.1

#### 1.3.1 Improvements and New Features

- Has better handling of opaque types.
  The handling of UTF segments of bitstreams has been significantly strengthened and revised. In all probability, now it is correct.
  Own Id: OTP-7958

### 1.4 Dialyzer 1.9.0

#### 1.4.1 Improvements and New Features

- The analysis accepts opaque type declarations and detects violations of opaqueness of terms of such types. Starting with R13, many Erlang/OTP standard libraries (array, dict, digraph, ets, gb_sets, gb_trees, queue, and sets) contain opaque type declarations of their main data types. Dialyzer will spit out warnings in code that explicitly depends on the structure of these terms.
  Added support for handling UTF segments in bitstreams and for detecting obvious type errors in these segments. Warning: This code is not terribly tested though since there are very few Erlang programs which use Unicode-based binaries - not surprising since this is a new language feature of R13.
  Strengthened the discrepancy identification when testing for equality and matching between terms of different types. This detects more bugs in code.
  Added warning for M:F(...) calls where M is not a module term and F is not an atom. Previously, such calls where found to fail but the reason for the failure was not reported.
  Added a convenient shorthand for the --no_check_plt option (-n).
  Added the --dump_callgraph option for dumping the callgraph of all files that are analyzed into a specified file. The callgraph either be dumped in raw format, in .dot format, or converted to a .ps (postscript) file. Note that in large callgraphs the generated postscript file might not be interpretable by Ghostview. (Thanks to Ilya Khlopotov for the initial version of this functionality.)
  Own Id: OTP-7864

### 1.5 Dialyzer 1.8.3

#### 1.5.1 Improvements and New Features

- Added the --no_check_plt option that makes the startup time faster when working with stable PLTs that do not change.
  Changed the phrasing of some warnings so that they do not cause confusion to some users and correspond better to reality.
  Own Id: OTP-7632

### 1.6 Dialyzer 1.8.2

#### 1.6.1 Improvements and New Features

- Minor updates.
  Own Id: OTP-7522

### 1.7 Dialyzer 1.8.1

#### 1.7.1 Improvements and New Features

- There is new --raw option for Dialyzer to output the result of the analysis in Erlang term, to faciliate later filtering and/or formatting.
  Own Id: OTP-7386
- The return type of the Erlang interface dialyzer:run/1 has changed to only return a list of warnings. If something goes wrong dialyzer dies with an exception.
  The handling of the PLT is now more flexible. There is no longer any default PLT included with OTP. Please consult the manual for the changes.
  Own Id: OTP-7389

### 1.8 Dialyzer 1.8.0

#### 1.8.1 Improvements and New Features

- Dialyzer's analysis is from now on exclusively based on success typings. In particular, support for options --old_style and --dataflow has been discontinued.
  Better and more aggressive handling of type information in records.
  Dialyzer has a new warning option -Wunmatched_returns which warns for function calls that ignore the return value. This catches many common programming errors (e.g. calling file:close/1 and not checking for the absence of errors), interface discrepancies (e.g. a function returning multiple values when in reality the function is void and only called for its side-effects), calling the wrong function (e.g. io_lib:format/1 instead of io:format/1), and even possible performance defects (e.g. unnecessarily constructing a list using a list comprehension instead of using lists:foreach/2). Whenever a function returns a single atomic value (e.g. 'ok' or pid()), the warning is suppressed. This allows for "void" functions (returning a single atom like 'ok') or for calls to certain builtins like spawn. Because not all calls which ignore the return value are discrepancies, the option is off by default and has to be explicitly requested by the user. But we recommend it nevertheless.
  Some warning options (-Wno_comp, -Wno_guards, -Wno_unsafe_beam, etc.) which could be used when analyzing bytecode produced by an old BEAM compiler have been removed.
  Own Id: OTP-7241

### 1.9 Dialyzer 1.7.2

#### 1.9.1 Improvements and New Features

- The warnings returned by the Erlang interface now contains a tag describing the type of warning.
  *** POTENTIAL INCOMPATIBILITY ***
  Own Id: OTP-7134

### 1.10 Dialyzer 1.7.1

#### 1.10.1 Improvements and New Features

- Use of success typings is now default, is robust and detects significantly more errors than in previous versions.
  Dialyzer now accepts and takes into account type information in record declarations and in contracts -- see related paper in Erlang'07 workshop. Various OTP applications (e.g. stdlib and kernel) are partially annotated with appropriate contracts specifying types information for their functions.
  The type previously known as unit() has been renamed to no_return(). Its use in a contract as the return type of a function now silences off the "function has no local return" dialyzer warning without use of the corresponding option.
  Own Id: OTP-6997

### 1.11 Dialyzer 1.7.0

#### 1.11.1 Improvements and New Features

- Minor Makefile changes.
  Own Id: OTP-6689
- Dialyzer can now use success typings to find discrepancies. As a consequence significantly more discrepancies are detected. The downside is that the analysis takes about 2 to 2.5 times longer than in previous versions, and may also result in some warnings that might be harder to interpret even though they are correct. This has been a major change, worth of increasing the version number.
  New command-line options:
  --succ_typings Use the success typings analysis.
  --dataflow (default) Use the previous analysis.
  The new type unit() has been introduced to handle the return type of non-terminating functions such as servers.
  Dialyzer's code server uses a compressed representation and the analysis requires significantly less memory than in previous versions.
  Own Id: OTP-6736

### 1.12 Dialyzer 1.6.0

#### 1.12.1 Improvements and New Features

- Dialyzer (in the modes where either source or BEAM code which contains debug_info is analyzed) spits out line information for all discrepancies. This has been a major change, worth of increasing the version number.
  We warn users that *considerably* more discrepancies are identified by this version of Dialyzer compared with previous ones and applications. If, for some reason, warnings generated by previous versions of Dialyzer are preferable, the command line option --old_style can be employed.
  Own Id: OTP-6546
- Dialyzer handles term comparison operators more precisely and is able to identify more discrepancies in 'if' or 'case' statements with comparisons.
  Dialyzer has more precise type information for many standard OTP functions.
  Own Id: OTP-6547

### 1.13 Dialyzer 1.5.1

#### 1.13.1 Improvements and New Features

- Updated the chapter "More on the Persistant Lookup Table (PLT)" in Dialyzer User's Guide and added information on how to use Dialyzer from Erlang to dialyzer(3). Also, the Dialyzer text files used by its GUI are now included in the Erlang/OTP release.
  Own Id: OTP-6361
- New options --check_init_plt and --verbose.
  Improvements in the analysis (meaning that this version can find more discrepancies than the previous version).
  Own Id: OTP-6421

### 1.14 Dialyzer 1.5.0

#### 1.14.1 Improvements and New Features

- Dialyzer's building of PLT is based on a different type inference algorithm. More specifically, Dialyzer uses inferrence of refined success typings to infer function prototypes. As a result, Dialyzer bases its analysis on a significantly more powerful basis and thus is able to detect more discrepancies. The downside is that building the PLT is a considerably slower process. We will work on improving that.
  Dialyzer takes into account the BEAM compiler directive -compile({nowarn_unused_function, {F,A}}). and then suppresses the warning that function F/A will never be called.
  Dialyzer's default initial PLT now also includes "mnesia".
  Own Id: OTP-6304

### 1.15 Dialyzer 1.4.2

#### 1.15.1 Improvements and New Features

- Improvements in PLT management.
  Own Id: OTP-6128

### 1.16 Dialyzer 1.4.1

#### 1.16.1 Fixed Bugs and Malfunctions

- Some minor changes.

#### 1.16.2 Improvements and New Features

- Some minor changes.

### 1.17 Dialyzer 1.4.0

#### 1.17.1 Fixed Bugs and Malfunctions

- Changes for Dialyzer to work with Erlang/OTP R10B-10.

#### 1.17.2 Improvements and New Features

- Dialyzer's analysis is significantly faster as it uses a global function call-graph for obtaining type signatures for all analyzed functions.

### 1.18 Dialyzer 1.3.1

#### 1.18.1 Fixed Bugs and Malfunctions

- Small changes for Dialyzer to work with Erlang/OTP R10B-5.
- Fixed a small buglet in the analysis; this affected one of HiPE's files.

#### 1.18.2 Improvements and New Features

- Modified setup script for execution under Cygwin (patch by Vlad Dumitrescu).
- Added command line option --no_warn_on_inline.
- Dialyzer now explicitly warns when modules with the same name but from different dirs are being analyzed (contribution by Ulf Wiger).

### 1.19 Dialyzer 1.3.0

#### 1.19.1 Fixed Bugs and Malfunctions

- Fixed a number of false positives that Dialyzer 1.2.0 was spitting out.

#### 1.19.2 Improvements and New Features

- Requires the presence of an Erlang/OTP R10B-4 system.
- Dialyzer is significantly (approx 40%) faster since it now uses 'ets' rather than 'dets' for its PLT.
- Slightly improved the precision of the analysis.
- In the GUI version, Dialyzer now reports the list of modules that should be included in the modules to analyze in order to possibly improve the accuracy of the reported results.
- Some more information is displayed when calling a function or closure with arguments of the wrong type.
- The record guard now allows discrepancies involving tuples that are known to be records to be displayed as #rec{} rather than {'rec',_,...,_}
- Added -q option which makes the command-line version of Dialyzer a bit more silent.

### 1.20 Dialyzer 1.2.0

#### 1.20.1 Improvements and New Features

- Dialyzer works with the open source and commercial versions of Erlang/OTP R10B-2 on all platforms (i.e., HiPE support is not a prerequisite anymore).
- Whenever a .beam file contains abstract code (i.e., has been compiled with the +debug_info option), the analysis starts from this code rather than from BEAM bytecode -- this makes the results identical to those obtained by analysis starting from source code. (This is a contribution from Bjorn Gustavsson - Thanks!)
- Added -pa command line option for easier handling of -include_lib() directives in source code.
- Includes all changes added in v1.1.1; see below. The "Add Recursively" functionality is also available in the command-line mode (-r option).

### 1.21 Dialyzer 1.1.1

#### 1.21.1 Fixed Bugs and Malfunctions

- Fixed problems using the shell script on Solaris machines.
- Fixed small inconsistencies in Dialyzer's documentation and help.

#### 1.21.2 Improvements and New Features

- The command-line mode of Dialyzer spits discrepancies in stdout by default and returns a numeric value indicating its exit status.
- Added "Add Recursively" button contributed by Martin Bjorklund (thanks!).

### 1.22 Dialyzer 1.1.0

#### 1.22.1 Improvements and New Features

- Dialyzer works with the open source version of Erlang/OTP R10B-1 (on platforms where HiPE support is available) and it does not require installation of a customized Erlang/OTP system anymore.
- Dialyzer comes with an extensive command-line interface, in addition to an enhanced GUI.
- Analysis can start from source code (through Core Erlang) as well as from BEAM bytecode.
- Dialyzer finds considerably more discrepancies in Erlang code than previous versions.
- Added ability to selectively turn on/off different warning categories.

### 1.23 Dialyzer 1.0.1

#### 1.23.1 Fixed Bugs and Malfunctions

- Fixed major bug of v1.0.0 which caused the analysis to stop prematurely (i.e., without properly reaching fixpoint) when analyzing more than one module. This did not affect correctness of the results, but lost many opportunities to detect discrepancies.

#### 1.23.2 Improvements and New Features

- Performance improvements in the analysis.

### 1.24 Dialyzer 1.0.0

#### 1.24.1 Improvements and New Features

- Initial Dialyzer version: Analysis starts from BEAM bytecode only and only a GUI version is available. Dialyzer reports discrepancies in the use of the "sequential" part of Erlang. To be used, Dialyzer requires the presence of a specific snapshot of Erlang/OTP which can be obtained from Dialyzer's homepage.

dialyzer 2.0.0
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