Compiler Mode: what changed
Revision 0 to 1. Removed lines have a minus sign; added lines have a plus sign.
Title: Compiler Mode
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| 1 | + | The [[FPC]] intends to be (in part) a free and open source alternative to commercial [[Pascal]] compilers. In order to achieve this a compiler switch determining the *compiler compatibility mode* has been introduced. | |
| 2 | + | ||
| 3 | + | Every mode implicitly enables or disables certain syntax requirements or other language constructs. Some of these can be enabled or disabled on an individual basis by using so called *mode switches*, see below. | |
| 4 | + | ||
| 5 | + | ## modes | |
| 6 | + | ||
| 7 | + | A compiler compatibility mode can be specified in [[Source code|source code]] via the [[global compiler directives|global compiler directive]] `{$mode}` or via the command line or `fpc.cfg(5)` parameter `-M`. | |
| 8 | + | ||
| 9 | + | The following nine compiler compatibility modes are recognized: | |
| 10 | + | ||
| 11 | + | Free Pascal ([[Mode FPC|{$mode FPC}]], `-MFPC`) | |
| 12 | + | This is the original FPC mode. As of FPC 3.x this is the *default mode* if neither the source code or the command line specifies a compiler compatibility mode explicitly. | |
| 13 | + | ||
| 14 | + | Object Pascal ([[Mode ObjFPC|{$mode objFPC}]], `-MobjFPC` or `-S2`) | |
| 15 | + | This mode adds extra functionality to the `FPC` mode, including but not limited to [[Class|classes]], [[Interface|interfaces]] and [[Exceptions|exceptions]]. | |
| 16 | + | ||
| 17 | + | [[Turbo Pascal]] ([[Mode TP|{$mode TP}]], `-MTP` or `-So`) | |
| 18 | + | This is the Turbo Pascal compatibility mode. It tries to be compatible to Borland TP 7.0, e. g. by disable function overloading. | |
| 19 | + | ||
| 20 | + | [[Delphi]] ([[Mode Delphi|{$mode Delphi}]], `-Mdelphi` or `-Sd`) | |
| 21 | + | This is the Delphi compatibility mode. | |
| 22 | + | ||
| 23 | + | Delphi with Unicode (`{$mode DelphiUnicode}`, `-MdelphiUnicode`) \[[[FPC New Features 3.0|since FPC 3.0.0]]\] | |
| 24 | + | Like `{$mode Delphi}` but with `unicodeString` as default `string` type. | |
| 25 | + | ||
| 26 | + | [[Mac Pascal]] ([[Mode MacPas|{$mode MacPas}]], `-MmacPas`) \[since FPC 1.9.0\] | |
| 27 | + | The Mac Pascal compatibility mode. | |
| 28 | + | ||
| 29 | + | [[GNU Pascal]] ([[Mode GPC|{$mode GPC}]], `-MGPC` or `-Sp`) \[removed since FPC 2.2.0\] | |
| 30 | + | The GNU Pascal compatibility mode. | |
| 31 | + | ||
| 32 | + | ISO 7185 [[Standard Pascal]] ([[Mode iso|{$mode ISO}]], `-MISO`) \[[[FPC New Features 2.6.0|since FPC 2.6.0]]\] | |
| 33 | + | The ISO 7185 compliant compatibility mode. | |
| 34 | + | ||
| 35 | + | [[Extended Pascal]] ([[Mode extendedpascal|{$mode extendedPascal}]]) \[since FPC 3.2\] | |
| 36 | + | This is the extended Pascal mode. It tries to be as ISO 10206 compliant as possible. | |
| 37 | + | ||
| 38 | + | Furthermore the special mode `default` reverts any specifications of a compiler compatibility mode. | |
| 39 | + | ||
| 40 | + | Since the specifications of compiler compatibility mode implicitly imposes rigorous changes and possibly implies inclusion of other modules, it is imperative to specify the directives prior any other. | |
| 41 | + | ||
| 42 | + | ## mode switch | |
| 43 | + | ||
| 44 | + | Since FPC 2.3.1 the global compiler directive [[modeswitches|{$modeSwitch}]] allows a selective selection of *some* features, despite the chosen mode. | |
| 45 | + | ||
| 46 | + | A mode switch has to appear after any mode selections, otherwise the mode switches will be overwritten. | |
| 47 | + | ||
| 48 | + | ``` pascal | |
| 49 | + | // omit @-address-operator while assigning to procedural variables, despite FPC mode | |
| 50 | + | {$mode FPC} | |
| 51 | + | {$modeSwitch classicProcVars+} | |
| 52 | + | ``` | |
| 53 | + | ||
| 54 | + | ## see also | |
| 55 | + | ||
| 56 | + | - [§ “compiler modes” in the *Free Pascal User’s manual*](https://www.freepascal.org/docs-html/user/userse33.html) | |
| 57 | + | ||
| 58 | + | --- | |
| 59 | + | *From the Free Pascal wiki, page "Compiler Mode", as it stood on 2019-10-21 after a change by Kai Burghardt, out of the wiki's dump of 2024-05-26. Copyright stays with the author who wrote it, according to the old wiki's [[Licensing]] page. If you have concerns about this material, [message the admin](/wiki-contact).* |