See the FixIt completer subcommand for more information. NOTE: The absence of FixIt available does not strictly imply a fix-it is not available as not all completers are able to provide this indication. For example, the c-sharp completer provides many fix-its but does not add this additional indication. See the Options section for details. This command shows the full diagnostic text when the user's cursor is on the line with the diagnostic. An options argument can be passed. If the argument is popup the diagnostic text will be displayed in a popup at cursor position.

This will print out various debug information for the current file. Useful to see what compile commands will be used for the file if you're using the semantic completion engine. This command presents the list of logfiles created by YCM, the ycmd server , and the semantic engine server for the current filetype, if any. One of these logfiles can be opened in the editor or closed if already open by entering the corresponding number or by clicking on it with the mouse.

Additionally, this command can take the logfile names as arguments. Each logfile given as an argument is directly opened or closed if already open in the editor. Only for debugging purposes.

This command gives access to a number of additional IDE-like features in YCM, for things like semantic GoTo, type information, FixIt and refactoring. This command accepts a range that can either be specified through a selection in one of Vim's visual modes see :h visual-use or on the command line. For instance, :2,5YcmCompleter will apply the command from line 2 to line 5. This is useful for the Format subcommand.

Call YcmCompleter without further arguments for a list of the commands you can call for the current completer. See the file type feature summary for an overview of the features available for each file type. See the YcmCompleter subcommands section for more information on the available subcommands and their usage. NOTE: See the docs for the YcmCompleter command before tackling this section.

The invoked subcommand is automatically routed to the currently active semantic completer, so :YcmCompleter GoToDefinition will invoke the GoToDefinition subcommand on the Python semantic completer if the currently active file is a Python one and on the Clang completer if the currently active file is a C-family language one.

These commands are useful for jumping around and exploring code. When moving the cursor, the subcommands add entries to Vim's jumplist so you can use CTRL-O to jump back to where you were before invoking the command and CTRL-I to jump forward; see :h jumplist for details.

If there is more than one destination, the quickfix list see :h quickfix is populated with the available locations and opened to full width at the bottom of the screen. You can change this behavior by using the YcmQuickFixOpened autocommand. Supported in filetypes: c, cpp, objc, objcpp, cuda, cs, go, java, javascript, python, rust, typescript.

NOTE: For C-family languages this only works in certain situations , namely when the definition of the symbol is in the current translation unit. A translation unit consists of the file you are editing and all the files you are including with include directives directly or indirectly in that file. This command tries to perform the "most sensible" GoTo operation it can. Currently, this means that it tries to look up the symbol under the cursor and jumps to its definition if possible; if the definition is not accessible from the current translation unit, jumps to the symbol's declaration.

For C-family languages, it first tries to look up the current line for a header and jump to it. For C , implementations are also considered and preferred. Same as the GoTo command except that it doesn't recompile the file with libclang before looking up nodes in the AST. This can be very useful when you're editing files that take long to compile but you know that you haven't made any changes since the last parse that would lead to incorrect jumps.

When you're just browsing around your codebase, this command can spare you quite a bit of latency. Finds the definition of all symbols matching a specified string. However, an interactive symbol search is also available. Supported in filetypes: c, cpp, objc, objcpp, cuda, cs, java, javascript, python, typescript.

This command attempts to find all of the references within the project to the identifier under the cursor and populates the quickfix list with those locations. Supported in filetypes: c, cpp, objc, objcpp, cuda, java, javascript, python, typescript, rust. Looks up the symbol under the cursor and jumps to its implementation i. If there are multiple implementations, instead provides a list of implementations to choose from. Looks up the symbol under the cursor and jumps to its implementation if one, else jump to its declaration.

Looks up the symbol under the cursor and jumps to the definition of its type e. if the symbol is an object, go to the definition of its class. Provides a list of symbols in current document, in the quickfix list. See also interactive symbol search. Populate the quickfix list with the callers, or callees respectively, of the function associated with the current cursor position. The semantics of this differ depending on the filetype and language server. Only supported for LSP servers which provide the callHierarchyProvider capability.

These commands are useful for finding static information about the code, such as the types of variables, viewing declarations and documentation strings. Echos the type of the variable or method under the cursor, and where it differs, the derived type.

Supported in filetypes: c, cpp, objc, objcpp, cuda, java, javascript, go, python, typescript, rust. Same as the GetType command except that it doesn't recompile the file with libclang before looking up nodes in the AST.

This can be very useful when you're editing files that take long to compile but you know that you haven't made any changes since the last parse that would lead to incorrect type. In the out-of-line definition of C::f , the semantic parent is the class C , of which this function is a member. In the example above, both declarations of C::f have C as their semantic context, while the lexical context of the first C::f is C and the lexical context of the second C::f is the translation unit.

Displays the preview window populated with quick info about the identifier under the cursor. Depending on the file type, this includes things like:. Supported in filetypes: c, cpp, objc, objcpp, cuda, cs, go, java, javascript, python, typescript, rust. Same as the GetDoc command except that it doesn't recompile the file with libclang before looking up nodes in the AST. This can be very useful when you're editing files that take long to compile but you know that you haven't made any changes since the last parse that would lead to incorrect docs.

These commands make changes to your source code in order to perform refactoring or code correction. YouCompleteMe does not perform any action which cannot be undone, and never saves or writes files to the disk. Where available, attempts to make changes to the buffer to correct diagnostics, or perform refactoring, on the current line or selection.

Where multiple suggestions are available such as when there are multiple ways to resolve a given warning, or where multiple diagnostics are reported for the current line, or multiple refactoring tweaks are available , the options are presented and one can be selected.

Completers which provide diagnostics may also provide trivial modifications to the source in order to correct the diagnostic. Examples include syntax errors such as missing trailing semi-colons, spurious characters, or other errors which the semantic engine can deterministically suggest corrections. A small demo presenting how diagnostics can be fixed with clangd:. Completers LSPs may also provide refactoring tweaks, which may be available even when no diagnostic is presented for the current line.

These include function extraction, variable extraction, switch population, constructor generation, The tweaks work for a selection as well. Consult your LSP for available refactorings. A demonstration of refactoring capabilities with clangd:. If no fix-it is available for the current line, or there is no diagnostic on the current line, this command has no effect on the current buffer.

If any modifications are made, the number of changes made to the buffer is echo'd and the user may use the editor's undo command to revert. The text FixIt available is also appended to the diagnostic text in the output of the :YcmDiags command for any diagnostics with available fix-its where the completer can provide this indication.

Supported in filetypes: c, cpp, objc, objcpp, cuda, cs, go, java, javascript, rust, typescript. In supported file types, this command attempts to perform a semantic rename of the identifier under the cursor. This includes renaming declarations, definitions and usages of the identifier, or any other language-appropriate action.

The specific behavior is defined by the semantic engine in use. Similar to FixIt , this command applies automatic modifications to your source files. Rename operations may involve changes to multiple files, which may or may not be open in Vim buffers at the time. YouCompleteMe handles all of this for you. The behavior is described in the following section. Supported in filetypes: c, cpp, objc, objcpp, cuda, java, javascript, python, typescript, rust, cs.

See the jedi docs for what they do. When a Refactor or FixIt command touches multiple files, YouCompleteMe attempts to apply those modifications to any existing open, visible buffer in the current tab. If no such buffer can be found, YouCompleteMe opens the file in a new small horizontal split at the top of the current window, applies the change, and then hides the window.

NOTE: The buffer remains open, and must be manually saved. A confirmation dialog is opened prior to doing this to remind you that this is about to happen. Once the modifications have been made, the quickfix list see :help quickfix is populated with the locations of all modifications. This can be used to review all automatic changes made by using :copen. It is possible to customize how the quickfix window is opened by using the YcmQuickFixOpened autocommand.

The buffers are not saved automatically. That is, you must save the modified buffers manually after reviewing the changes from the quickfix list. Changes can be undone using Vim's powerful undo features see :help undo. Note that Vim's undo is per-buffer, so to undo all changes, the undo commands must be applied in each modified buffer separately. NOTE: While applying modifications, Vim may find files which are already open and have a swap file.

The command is aborted if you select Abort or Quit in any such prompts. This leaves the Refactor operation partially complete and must be manually corrected using Vim's undo features. The quickfix list is not populated in this case. Inspect :buffers or equivalent see :help buffers to see the buffers that were opened by the command.

This command formats the whole buffer or some part of it according to the value of the Vim options shiftwidth and expandtab see :h 'sw' and :h et respectively.

To format a specific part of your document, you can either select it in one of Vim's visual modes see :h visual-use and run the command or directly enter the range on the command line, e. Supported in filetypes: c, cpp, objc, objcpp, cuda, java, javascript, go, typescript, rust, cs.

This command removes unused imports and sorts imports in the current file. It can also group imports from the same module in TypeScript and resolves imports in Java. These commands are for general administration, rather than IDE-like features. They cover things like the semantic engine server instance and compilation flags. Some LSP completers currently only Java completers support executing server specific commands.

Consult the jdt. ls documentation to find out what commands are supported and which arguments are expected. The support for ExecuteCommand was implemented to support plugins like Vimspector to debug java, but isn't limited to that specific use case. Restarts the downstream semantic engine server for those semantic engines that work as separate servers that YCM talks to.

Instruct the Omnisharp-Roslyn server to clear its cache and reload all files from disk. This is useful when files are added, removed, or renamed in the solution, files are changed outside of Vim, or whenever Omnisharp-Roslyn cache is out-of-sync.

Get the number of YCM Diagnostic errors. If no errors are present, this function returns 0. Both this function and youcompleteme GetWarningCount can be useful when integrating YCM with other Vim plugins.

For example, a lightline user could add a diagnostics section to their statusline which would display the number of errors and warnings. Get the number of YCM Diagnostic warnings. If no warnings are present, this function returns 0. Run a completer subcommand and return the result as a string.

This can be useful for example to display the GetGoc output in a popup window, e. If the completer subcommand result is not a string for example, it's a FixIt or a Location , or if the completer subcommand raises an error, an empty string is returned, so that calling code does not have to check for complex error conditions.

The arguments to the function are the same as the arguments to the :YcmCompleter ex command, e. the name of the subcommand, followed by any additional subcommand arguments. This is an advanced usage and not necessary in most cases. NOTE: The request is run synchronously and blocks Vim until the response is received, so we do not recommend running this as part of an autocommand that triggers frequently. This works exactly like youcompleteme GetCommandResponse , except that instead of returning the result, you supply a callback argument.

This argument must be a FuncRef to a function taking a single argument response. This callback will be called with the command response at some point later, or immediately.

As with youcompleteme GetCommandResponse , this function will call the callback with '' an empty string if the request is not sent, or if there was some sort of error. NOTE : The callback may be called immediately, in the stack frame that called this function. NOTE : Only one command request can be outstanding at once. Attempting to request a second responses while the first is outstanding will result in the second callback being immediately called with ''. This User autocommand is fired when YCM opens the location list window in response to the YcmDiags command.

By default, the location list window is opened to the bottom of the current window and its height is set to fit all entries. This behavior can be overridden by using the YcmLocationOpened autocommand which is triggered while the cursor is in the location list window. For instance:. By default, the quickfix window is opened to full width at the bottom of the screen and its height is set to fit all entries.

This behavior can be overridden by using the YcmQuickFixOpened autocommand which is triggered while the cursor is in the quickfix window. All options have reasonable defaults so if the plug-in works after installation you don't need to change any options.

These options can be configured in your vimrc script by including a line like this:. Note that after changing an option in your vimrc script you have to restart ycmd with the :YcmRestartServer command for the changes to take effect. This option controls the number of characters the user needs to type before identifier-based completion suggestions are triggered. For example, if the option is set to 2 , then when the user types a second alphanumeric character after a whitespace character, completion suggestions will be triggered.

This option is NOT used for semantic completion. Setting this option to a high number like 99 effectively turns off the identifier completion engine and just leaves the semantic engine. This option controls the minimum number of characters that a completion candidate coming from the identifier completer must have to be shown in the popup menu. NOTE: This option only applies to the identifier completer; it has no effect on the various semantic completers.

This option controls the maximum number of semantic completion suggestions shown in the completion menu. NOTE: Setting this option to 0 or to a value greater than is not recommended as it will slow down completion when there are a very large number of suggestions.

Some completion engines require completion candidates to be 'resolved' in order to get detailed info such as inline documentation, method signatures etc. This information is displayed by YCM in the preview window, or if completeopt contains popup , in the info popup next to the completion menu. By default, if the info popup is in use, and there are more than 10 candidates, YCM will defer resolving candidates until they are selected in the completion menu.

Otherwise, YCM must resolve the details upfront, which can be costly. If neither popup nor preview are in completeopt , YCM disables resolving altogether as the information would not be displayed.

This setting can be used to override these defaults and controls the number of completion candidates that should be resolved upfront. However, you may override this calculation by setting this value to a number:.

In the later two cases, if completeopt contains popup , then candidates are resolved on demand asynchronously. This option controls the maximum number of completion suggestions from the identifier-based engine shown in the completion menu. When set to 0 , this option turns off YCM's identifier completer the as-you-type popup and the semantic triggers the popup you'd get after typing.

This option controls for which Vim filetypes see :h filetype should YCM be turned on. The option value should be a Vim dictionary with keys being filetype strings like python , cpp , etc.

and values being unimportant the dictionary is used like a hash set, meaning that only the keys matter. YCM will work only in filetypes that both the whitelist and the blacklist allow the blacklist "allows" a filetype by not having it as a key. For example, let's assume you want YCM to work in files with the cpp filetype. It should not be present in the blacklist. Filetypes that are blocked by the either of the lists will be completely ignored by YCM, meaning that neither the identifier-based completion engine nor the semantic engine will operate in them.

There is one exception to the above rule. YCM supports completion in buffers with no filetype set, but this must be explicitly whitelisted. To enable completion in buffers with no filetype, set:. This option controls for which Vim filetypes see :h filetype should YCM be turned off. This option controls for which Vim filetypes see :h filetype should the YCM semantic completion engine be turned off.

The listed filetypes will be ignored by the YCM semantic completion engine, but the identifier-based completion engine will still trigger in files of those filetypes. Note that even if semantic completion is not turned off for a specific filetype, you will not get semantic completion if the semantic engine does not support that filetype. This option controls for which Vim filetypes see :h filetype should filepath completion be disabled.

Use this key if you want to completely disable filepath completion:. When set, this option turns on YCM's diagnostic display features. See the Diagnostic display section in the User Manual for more details. Specific parts of the diagnostics UI like the gutter signs, text highlighting, diagnostic echo and auto location list population can be individually turned on or off.

See the other options below for details. When set, this option also makes YCM remove all Syntastic checkers set for the c , cpp , objc , objcpp , and cuda filetypes since this would conflict with YCM's own diagnostics UI.

If you're using YCM's identifier completer in C-family languages but cannot use the clang-based semantic completer for those languages and want to use the GCC Syntastic checkers, unset this option. When this option is set, YCM will put icons in Vim's gutter on lines that have a diagnostic set.

Turning this off will also turn off the YcmErrorLine and YcmWarningLine highlighting. When this option is set, YCM will highlight regions of text that are related to the diagnostic that is present on a line, if any. When this option is set to 1, YCM will echo the text of the diagnostic present on the current line when you move your cursor to that line. If a FixIt is available for the current diagnostic, then FixIt is appended.

If you have a vim that supports virtual text, you can set this option to the string virtual-text , and the diagnostic will be displayed inline with the text, right aligned in the window and wrapping to the next line if there is not enough space, for example:.

This is due to the increased amount distraction provided by drawing diagnostics next to your input position. This option controls whether or not YCM shows documentation in a popup at the cursor location after a short delay.

Only supported in Vim. When this option is set to 'CursorHold' , the popup is displayed on the CursorHold autocommand. See :help CursorHold for the details, but this means that it is displayed after updatetime milliseconds.

When set to an empty string, the popup is not automatically displayed. After dismissing the popup with this mapping, it will not be automatically triggered again until the cursor is moved i. CursorMoved autocommand. The displayed documentation depends on what the completer for the current language supports. It's selected heuristically in this order of preference:. This buffer-local variable can be set to a dictionary with the following keys:.

This option controls which diagnostics will be rendered by YCM. This option holds a dictionary of key-values, where the keys are Vim's filetype strings delimited by commas and values are dictionaries describing the filter. A filter is a dictionary of key-values, where the keys are the type of filter, and the value is a list of arguments to that filter. In the case of just a single item in the list, you may omit the brackets and just provide the argument directly.

If any filter matches a diagnostic, it will be dropped and YCM will not render it. NOTE: The regex syntax is NOT Vim's, it's Python's. When this option is set, YCM will populate the location list automatically every time it gets new diagnostic data. This option is off by default so as not to interfere with other data you might have placed in the location list. Note: if YCM's errors aren't visible, it might be that YCM is updating an older location list.

See :help :lhistory and :lolder. When this option is set, :YcmDiags will automatically open the location list after forcing a compilation and filling the list with diagnostic data. When this option is set to 1 , YCM will show the completion menu even when typing inside comments.

When this option is set to 1 , YCM will show the completion menu even when typing inside strings. Note that this is turned on by default so that you can use the filename completion inside strings. This is very useful for instance in C-family files where typing include " will trigger the start of filename completion.

If you turn off this option, you will turn off filename completion in such situations as well. When this option is set to 1 , YCM's identifier completer will also collect identifiers from strings and comments.

Otherwise, the text in comments and strings will be ignored. When this option is set to 1 , YCM's identifier completer will also collect identifiers from tags files. The list of tags files to examine is retrieved from the tagfiles Vim function which examines the tags Vim option. See :h 'tags' for details. The only supported tag format is the Exuberant Ctags format. The format from "plain" ctags is NOT supported. This option is off by default because it makes Vim slower if your tags are on a network directory.

When this option is set to 1 , YCM's identifier completer will seed its identifier database with the keywords of the programming language you're writing. Since the keywords are extracted from the Vim syntax file for the filetype, all keywords may not be collected, depending on how the syntax file was written. If you're using semantic completion for C-family files, this option might come handy; it's a way of sending data from Vim to your Settings function in your.

For instance, if you set this option to ['v:version'] , your Settings function will be called like this:. YCM will by default search for an appropriate Python interpreter on your system. You can use this option to override that behavior and force the use of a specific interpreter of your choosing. NOTE: This interpreter is only used for the ycmd server. The YCM client running inside Vim always uses the Python interpreter that's embedded inside Vim.

When this option is set to 1 , YCM and the ycmd completion server will keep the logfiles around after shutting down they are deleted on shutdown by default. The logging level that YCM and the ycmd completion server use. Valid values are the following, from most verbose to least verbose:. When set to 1 , the OmniSharp-Roslyn server will be automatically started once per Vim session when you open a C file.

When set to 1 , the OmniSharp-Roslyn server will be automatically stopped upon closing Vim. When set to 0 uses an unused port provided by the OS. By default, when YCM inserts a namespace, it will insert the using statement under the nearest using statement. You may prefer that the using statement is inserted somewhere, for example, to preserve sorting.

If so, you can set this option to override this behavior. The option's expression is responsible for inserting the namespace - the default insertion will not occur. When this option is set to 1 , YCM will add the preview string to Vim's completeopt option see :h completeopt. If your completeopt option already has preview set, there will be no effect. Alternatively, when set to popup and your version of Vim supports popup windows see :help popup , the popup string will be used instead.

You can see the current state of your completeopt setting with :set completeopt? yes, the question mark is important. When preview is present in completeopt , YCM will use the preview window at the top of the file to store detailed information about the current completion candidate but only if the candidate came from the semantic engine.

For instance, it would show the full function prototype and all the function overloads in the window if the current completion is a function name. When popup is present in completeopt , YCM will instead use a popup window to the side of the completion popup for storing detailed information about the current completion candidate. In addition, YCM may truncate the detailed completion information in order to give the popup sufficient room to display that detailed information.

When this option is set to 1 , YCM will auto-close the preview window after the user accepts the offered completion string. If there is no preview window triggered because there is no preview string in completeopt , this option is irrelevant. When this option is set to 1 , YCM will auto-close the preview window after the user leaves insert mode.

Anyway, I though that it is a completely different topic. Please don't say that ELF file format specifications are the ABI. It doesn't qualify to be an interface according to the definition. I know, since we are talking at such a low level it must be very specific. But I'm not sure how is it "instruction set architecture ISA " specific?

You are already familiar with the concept of an API. If you want to use the features of, say, some library or your OS, you will program against an API. An ABI is very similar. Think of it as the compiled version of an API or as an API on the machine-language level. When you write source code, you access the library through an API. Once the code is compiled, your application accesses the binary data in the library through the ABI.

The ABI defines the structures and methods that your compiled application will use to access the external library just like the API did , only on a lower level. Your API defines the order in which you pass arguments to a function. Your ABI defines the mechanics of how these arguments are passed registers, stack, etc.

Your API defines which functions are part of your library. Your ABI defines how your code is stored inside the library file, so that any program using your library can locate the desired function and execute it.

ABIs are important when it comes to applications that use external libraries. Libraries are full of code and other resources, but your program has to know how to locate what it needs inside the library file. Your ABI defines how the contents of a library are stored inside the file, and your program uses the ABI to search through the file and find what it needs.

If everything in your system conforms to the same ABI, then any program is able to work with any library file, no matter who created them. Linux and Windows use different ABIs, so a Windows program won't know how to access a library compiled for Linux. Sometimes, ABI changes are unavoidable.

When this happens, any programs that use that library will not work unless they are re-compiled to use the new version of the library. If the ABI changes but the API does not, then the old and new library versions are sometimes called "source compatible". This implies that while a program compiled for one library version will not work with the other, source code written for one will work for the other if re-compiled.

For this reason, developers tend to try to keep their ABI stable to minimize disruption. Keeping an ABI stable means not changing function interfaces return type and number, types, and order of arguments , definitions of data types or data structures, defined constants, etc.

New functions and data types can be added, but existing ones must stay the same. If, for instance, your library uses bit integers to indicate the offset of a function and you switch to bit integers, then already-compiled code that uses that library will not be accessing that field or any following it correctly.

Accessing data structure members gets converted into memory addresses and offsets during compilation and if the data structure changes, then these offsets will not point to what the code is expecting them to point to and the results are unpredictable at best.

An ABI isn't necessarily something you will explicitly provide unless you are doing very low-level systems design work. It isn't language-specific either, since for example a C application and a Pascal application can use the same ABI after they are compiled. Edit: Regarding your question about the chapters regarding the ELF file format in the SysV ABI docs: The reason this information is included is because the ELF format defines the interface between operating system and application.

When you tell the OS to run a program, it expects the program to be formatted in a certain way and for example expects the first section of the binary to be an ELF header containing certain information at specific memory offsets. This is how the application communicates important information about itself to the operating system. If you build a program in a non-ELF binary format such as a. out or PE , then an OS that expects ELF-formatted applications will not be able to interpret the binary file or run the application.

This is one big reason why Windows apps cannot be run directly on a Linux machine or vice versa without being either re-compiled or run inside some type of emulation layer that can translate from one binary format to another.

IIRC, Windows currently uses the Portable Executable or, PE format. There are links in the "external links" section of that Wikipedia page with more information about the PE format.

An ABI can define a standard way of encoding the name of a function so that programs built with a different language or compiler can locate what they need. If you know assembly and how things work at the OS-level, you are conforming to a certain ABI. The ABI govern things like how parameters are passed, where return values are placed. For many platforms there is only one ABI to choose from, and in those cases the ABI is just "how things work".

This is necessary if you want to be able to pass object references across module boundaries or if you want to mix code compiled with different compilers. Also, if you have an bit OS which can execute bit binaries, you will have different ABIs for and bit code. In general, any code you link into the same executable must conform to the same ABI. If you want to communicate between code using different ABIs, you must use some form of RPC or serialization protocols.

I think you are trying too hard to squeeze in different types of interfaces into a fixed set of characteristics. For example, an interface doesn't necessarily have to be split into consumers and producers.

An interface is just a convention by which two entities interact. ABIs can be partially ISA-agnostic. A well defined ABI is very important for people writing compilers. Without a well defined ABI, it would be impossible to generate interoperable code. The ABI is set of rules that compilers and linkers adhere to in order to compile your program so that will work properly.

ABIs cover multiple topics:. The machine itself has no concept of "functions". This is a label , which will eventually get resolved into an address by the assembler. This label marks the "start" of your "function" in the assembly code. In high-level code, when you "call" that function, what you're really doing is causing the CPU to jump to the address of that label and continue executing there. In preparation for the jump, the compiler must do a bunch of important stuff.

The calling convention is like a checklist that the compiler follows to do all this stuff:. Here is a great page that actually shows the differences in the assembly generated when compiling for different ABIs.

Another thing to mention is that an ABI isn't only relevant inside your program's executable module. It's also used by the linker to make sure your program calls library functions correctly. You have multiple shared libraries running on your computer, and as long as your compiler knows what ABI they each use, it can call functions from them properly without blowing up the stack. Your compiler understanding how to call library functions is extremely important.

On a hosted platform that is, one where an OS loads programs , your program can't even blink without making a kernel call. An application binary interface ABI is similar to an API, but the function is not accessible to the caller at source code level. ABIs may be defined at the processor-architecture level or at the OS level. The ABIs are standards to be followed by the code-generator phase of the compiler.

The standard is fixed either by the OS or by the processor. Provide the mechanism which allows JNI, or a Python-C interface, etc. Consumer: Another function including one in another language, compiled by another compiler, or linked by another linker.

In the context of shared libraries, the most important implication of "having a stable ABI" is that you don't need to recompile your programs after the library changes. if you are selling a shared library, you save your users the annoyance of recompiling everything that depends on your library for every new release.

if you are selling closed source program that depends on a shared library present in the user's distribution, you could release and test less prebuilts if you are certain that ABI is stable across certain versions of the target OS.

This is specially important in the case of the C standard library, which many many programs in your system link to. then the old generated assembly still accesses the first int of the struct, and the program still works, because we kept the ABI stable. Here is a fully automated version of this example on GitHub. This makes it easier to keep the ABI stable, but would incur a performance overhead as we'd do more function calls.

What this means, is that if we had recompiled our main. c program against the library, it would have worked regardless. The semantic API, is usually a natural language description of what the API is supposed to do, usually included in the API documentation.

then this would have broken neither programming API, nor ABI, but main. c the semantic API would break. formal verification. As long as there isn't a bug in your formal description of course ;-. What is binary compatibility in Java? Functionality: A set of contracts which affect the compiler, assembly writers, the linker, and the operating system.

The contracts specify how functions are laid out, where parameters are passed, how parameters are passed, how function returns work. These are generally specific to a processor architecture, operating system tuple. Existing entities: parameter layout, function semantics, register allocation. For instance, the ARM architectures has numerous ABIs APCS, EABI, GNU-EABI, never mind a bunch of historical cases - using the a mixed ABI will result in your code simply not working when calling across boundaries.

The compiler, assembly writers, linkers which do code generation or alignment requirements , operating system interrupt handling, syscall interface. If you did assembly programming, you were conforming to an ABI! It is not a linker level issue, but instead a code generation issue.

ELF is a file format for the use of a loader and dynamic linker. ELF is a container format for binary code and data, and as such specifies the ABI of a piece of code.

I would not consider ELF to be an ABI in the strict sense, as PE executables are not an ABI. All ABIs are instruction set specific.

Windows has several ABIs - for instance, fastcall and stdcall are two common use ABIs. The syscall ABI is different again. Let me at least answer a part of your question. With an example of how the Linux ABI affects the systemcalls, and why that is usefull.

A systemcall is a way for a userspace program to ask the kernelspace for something. It works by putting the numeric code for the call and the argument in a certain register and triggering an interrupt. Than a switch occurs to kernelspace and the kernel looks up the numeric code and the argument, handles the request, puts the result back into a register and triggers a switch back to userspace. This is needed for example when the application wants to allocate memory or open a file syscalls "brk" and "open".

Now the syscalls have short names "brk", etc. and corresponding opcodes, these are defined in a system specific header file. As long as these opcodes stay the same you can run the same compiled userland programs with different updated kernels without having to recompile. So you have an interface used by precompiled binarys, hence ABI. There are various interpretation and strong opinions of the exact layer that define an ABI application binary interface.

The ABI is the "rest" of conventions that "will not change" for a specific API or that will be addressed by the runtime environment: executors, tools, linkers, compilers, jvm, and OS. The library follows best practices and use Semantic Versioning. This defines the API compatibility at three levels:. In order for you to use a new major release of the same library a lot of other conventions are still to be respected:.

For example, Java standardized all these conventions, not in a tool, but in a formal JVM specification. The specification allowed other vendors to provide a different set of tools that can output compatible libraries.

Java provides two other interesting case studies for ABI: Scala versions and Dalvik virtual machine. The Dalvik VM needs a different type of bytecode than the Java bytecode. The Dalvik libraries are obtained by converting the Java bytecode with same API for Dalvik.

In this way you can get two versions of the same API: defined by the original joda-time We could call it joda-time jar and joda-time They use a different ABI one is for the stack-oriented standard Java vms: Oracle's one, IBM's one, open Java or any other; and the second ABI is the one around Dalvik. Scala doesn't have binary compatibility between minor Scala versions: 2. For this reason the same API "io. What is changed? I don't know for now , but the binaries are not compatible. Java has problems with the major releases of the JVM too: 4,5,6,7,8,9.

They offer only backward compatibility. All these while you have one joda-library. This incompatibility flies bellow the radar thanks to different solutions:. API and ABI are just conventions on how you define compatibility. The lower layers are generic in respect of a plethora of high level semantics. That's why it's easy to make some conventions. The first kind of conventions are about memory alignment, byte encoding, calling conventions, big and little endian encodings, etc.

On top of them you get the executable conventions like others described, linking conventions, intermediate byte code like the one used by Java or LLVM IR used by GCC. Third you get conventions on how to find libraries, how to load them see Java classloaders.

As you go higher and higher in concepts you have new conventions that you consider as a given. That's why they didn't made it to the semantic versioning. They are implicit or collapsed in the major version. When you say APK you already talk about a specific ABI part of your API. Let's say I have some sources for rxscala. If the Scala tools are changed I can recompile them to that. If the JVM changes I could have automatic conversions from the old machine to the new one without bothering with the high level concepts.

While porting might be difficult will help any other client. If a new operating system is created using a totally different assembler code a translator can be created. There are APIs that are ported in multiple languages like reactive streams.

I would argue that the API is the master specification formally defined in human language or even a specific programming language. All the other "mappings" are ABI in a sense, else more API than the usual ABI.

The same is happening with the REST interfaces. In order to call code in shared libraries, or call code between compilation units, the object file needs to contain labels for the calls. For free! Did you know Skype Bing mashup happened? Here are the results - a unique high-quality background images in your Skype calls!

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Work fast with our official CLI. Learn more. Please sign in to use Codespaces. If nothing happens, download GitHub Desktop and try again. If nothing happens, download Xcode and try again. There was a problem preparing your codespace, please try again. First carefully read the installation instructions for your OS.

We recommend you use the supplied install. py - the "full" installation guide is for rare, advanced use cases and most users should use install. If the server isn't starting and you're getting a "YouCompleteMe unavailable" error, check the Troubleshooting guide.

Next check the User Guide section on the semantic completer that you are using. Finally, check the FAQ. If, after reading the installation and user guides, and checking the FAQ, you're still having trouble, check the contacts section below for how to get in touch. Please do NOT go to vim on Freenode for support. Please contact the YouCompleteMe maintainers directly using the contact details below.

YouCompleteMe is a fast, as-you-type, fuzzy-search code completion, comprehension and refactoring engine for Vim. It has several completion engines built in and supports any protocol-compliant Language Server, so can work with practically any language. YouCompleteMe contains:. First, realize that no keyboard shortcuts had to be pressed to get the list of completion candidates at any point in the demo.

The user just types and the suggestions pop up by themselves. When the user sees a useful completion string being offered, they press the TAB key to accept it. This inserts the completion string. Repeated presses of the TAB key cycle through the offered completions. If the offered completions are not relevant enough, the user can continue typing to further filter out unwanted completions.

A critical thing to notice is that the completion filtering is NOT based on the input being a string prefix of the completion but that works too. The input needs to be a subsequence match of a completion. This is a fancy way of saying that any input characters need to be present in a completion string in the order in which they appear in the input. So abc is a subsequence of xaybgc , but not of xbyxaxxc. After the filter, a complicated sorting system ranks the completion strings so that the most relevant ones rise to the top of the menu so you usually need to press TAB just once.

All of the above works with any programming language because of the identifier-based completion engine. It collects all of the identifiers in the current file and other files you visit and your tags files and searches them when you type identifiers are put into per-filetype groups.

The demo also shows the semantic engine in use. When the user presses. The last thing that you can see in the demo is YCM's diagnostic display features the little red X that shows up in the left gutter; inspired by Syntastic if you are editing a C-family file.

As the completer engine compiles your file and detects warnings or errors, they will be presented in various ways. You don't need to save your file or press any keyboard shortcut to trigger this, it "just happens" in the background. YCM might be the only vim completion engine with the correct Unicode support. Though we do assume UTF-8 everywhere. YCM also provides semantic IDE-like features in a number of languages, including:.

And here's some documentation being shown in a hover popup, automatically and manually:. Features vary by file type, so make sure to check out the file type feature summary and the full list of completer subcommands to find out what's available for your favourite languages. You'll also find that YCM has filepath completers try typing. Our policy is to support the Vim version that's in the latest LTS of Ubuntu.

That's currently Ubuntu Vim must have a working Python 3. You can check with :py3 import sys; print sys. For Neovim users, our policy is to require the latest released version.

Currently, Neovim 0. Please note that some features are not available in Neovim, and Neovim is not officially supported. This requires a version bump of the minimum supported compilers. The new requirements are:. YCM requires CMake 3.

If your CMake is too old, you may be able to simply pip install --user cmake to get a really new version. When enabling language support for a particular language, there may be runtime requirements, such as needing a very recent Java Development Kit for Java support.

In general, YCM is not in control of the required versions for the downstream compilers, though we do our best to signal where we know them.

Install mono from Mono Project NOTE: on Intel Macs you can also brew install mono. On arm Macs, you may require Rosetta. Pre-installed macOS system Vim does not support Python 3. So you need to install either a Vim that supports Python 3 OR MacVim with Homebrew :.

For using an arbitrary LSP server, check the relevant section. These instructions using install. py are the quickest way to install YouCompleteMe, however they may not work for everyone. If the following instructions don't work for you, check out the full installation guide. A supported Vim version with Python 3 is required. MacVim is a good option, even if you only use the terminal. YCM won't work with the pre-installed Vim from Apple as its Python support is broken.

If you don't already use a Vim that supports Python 3 or MacVim , install it with Homebrew. Install CMake as well:. Install YouCompleteMe with Vundle. Remember: YCM is a plugin with a compiled component. You should then rerun the install process. NOTE: If you want C-family completion, you MUST have the latest Xcode installed along with the latest Command Line Tools they are installed automatically when you run clang for the first time, or manually by running xcode-select --install.

Compiling YCM with semantic support for C-family languages through clangd :. To simply compile with everything enabled, there's a --all flag. So, to install with all language features, ensure xbuild , go , node and npm tools are installed and in your PATH , then simply run:.

That's it. You're done. Refer to the User Guide section on how to use YCM. Don't forget that if you want the C-family semantic completion engine to work, you will need to provide the compilation flags for your project to YCM. It's all in the User Guide.

YCM comes with sane defaults for its options, but you still may want to take a look at what's available for configuration. There are a few interesting options that are conservatively turned off by default that you may want to turn on.

Make sure you have a supported version of Vim with Python 3 support, and a supported compiler. The latest LTS of Ubuntu is the minimum platform for simple installation. For earlier releases or other distributions, you may have to do some work to acquire the dependencies. If your vim version is too old, you may need to compile Vim from source don't worry, it's easy.

Important: we assume that you are using the cmd. exe command prompt and that you know how to add an executable to the PATH environment variable. Make sure you have a supported Vim version with Python 3 support. You can check the version and which Python is supported by typing :version inside Vim. Take note of the Vim architecture, i. It will be important when choosing the Python installer. We recommend using a bit client. Daily updated installers of bit and bit Vim with Python 3 support are available.

Add the following line to your vimrc if not already present. This option is required by YCM. Note that it does not prevent you from editing a file in another encoding than UTF So, to install with all language features, ensure msbuild , go , node and npm tools are installed and in your PATH , then simply run:. YCM officially supports MSVC 15 , MSVC 16 Visual Studio and MSVC 17 Visual Studio 17

which help the developer understand the semantics of the code. This system was designed this way so that the user can perform any arbitrary sequence of operations to produce a list of compilation flags YCM should hand to Clang. Please note: The YCM maintainers do not specifically endorse nor necessarily have any relationship with the above charities. The speed of business has never been faster than it is today. For instance, :2,5YcmCompleter will apply the command from line 2 to line 5. Overall, do you approve or disapprove of the way Alex Padilla is handling his job as US Senator?

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