# Extra Clang Tools 8 documentation

## Extra Clang Tools 8.0.0 Release Notes

- Introduction

- What’s New in Extra Clang Tools 8.0.0?

  - Improvements to clangd

  - Improvements to clang-query

  - Improvements to clang-tidy

Written by the LLVM Team

## Introduction

This document contains the release notes for the Extra Clang Tools, part of the Clang release 8.0.0. Here we describe the status of the Extra Clang Tools in some detail, including major improvements from the previous release and new feature work. All LLVM releases may be downloaded from the LLVM releases web site.

For more information about Clang or LLVM, including information about the latest release, please see the Clang Web Site or the LLVM Web Site.

## What’s New in Extra Clang Tools 8.0.0?

Some of the major new features and improvements to Extra Clang Tools are listed here. Generic improvements to Extra Clang Tools as a whole or to its underlying infrastructure are described first, followed by tool-specific sections.

### Improvements to clangd

- clangd now adds namespace qualifiers in code completion, for example, if you type “`vec`”, the list of completions will include “`std::vector`”.

  See also: r343248.

- When a global index is available, clangd will use it to augment the results of “go to definition” and “find references” queries. Global index also enables global code completion, which suggests symbols that are not imported in the current file and automatically inserts the missing `#include` directives.

- clangd stores the symbol index on disk in a new compact binary serialization format. It is 10x more compact than YAML and 40% more compact than gzipped YAML.

  See also: r341375.

- clangd has a new efficient symbol index suitable for complex and fuzzy queries and large code bases (e.g., LLVM, Chromium). This index is used for code completion, go to definition, and cross-references. The architecture of the index allows for complex and fuzzy retrieval criteria and sophisticated scoring.

  See also: discussion on the mailing list, design doc.

- clangd has a new LSP extension that communicates information about activity on clangd’s per-file worker thread. This information can be displayed to users to let them know that the language server is busy with something. For example, in clangd, building the AST blocks many other operations.

  More info: File status.

- clangd has a new LSP extension that allows the client to supply the compilation commands over LSP, instead of finding compile_commands.json on disk.

  More info: Compilation commands.

- clangd has a new LSP extension that allows the client to request fixes to be sent together with diagnostics, instead of asynchronously.

  More info: Inline fixes for diagnostics.

- clangd has a new LSP extension that allows the client to resolve a symbol in a light-weight manner, without retrieving further information (like definition location, which may require consulting an index).

  More info: Symbol info request.

### Improvements to clang-query

- A new command line parameter `--preload` was added to run commands from a file and then start the interactive interpreter.

- The command `q` can was added as an alias for `quit` to exit the `clang-query` interpreter.

- It is now possible to bind to named values (the result of `let` expressions). For example:

      let fn functionDecl()
      match fn.bind("foo")

- It is now possible to write comments in `clang-query` code. This is primarily useful when using script-mode. Comments are all content following the `#` character on a line:

      # This is a comment
      match fn.bind("foo") # This is a trailing comment

- The new `set print-matcher true` command now causes `clang-query` to print the evaluated matcher together with the resulting bindings.

- A new output mode `detailed-ast` was added to `clang-query`. The existing `dump` output mode is now a deprecated alias for `detailed-ast`

- Output modes can now be enabled or disabled non-exclusively. For example,

      # Enable detailed-ast without disabling other output, such as diag
      enable output detailed-ast
      m functionDecl()

      # Disable detailed-ast only
      disable output detailed-ast
      m functionDecl()

### Improvements to clang-tidy

- New abseil-duration-comparison check.

  Checks for comparisons which should be done in the `absl::Duration` domain instead of the float of integer domains.

- New abseil-duration-division check.

  Checks for uses of `absl::Duration` division that is done in a floating-point context, and recommends the use of a function that returns a floating-point value.

- New abseil-duration-factory-float check.

  Checks for cases where the floating-point overloads of various `absl::Duration` factory functions are called when the more-efficient integer versions could be used instead.

- New abseil-duration-factory-scale check.

  Checks for cases where arguments to `absl::Duration` factory functions are scaled internally and could be changed to a different factory function.

- New abseil-duration-subtraction check.

  Checks for cases where subtraction should be performed in the `absl::Duration` domain.

- New abseil-faster-strsplit-delimiter check.

  Finds instances of `absl::StrSplit()` or `absl::MaxSplits()` where the delimiter is a single character string literal and replaces with a character.

- New abseil-no-internal-dependencies check.

  Gives a warning if code using Abseil depends on internal details.

- New abseil-no-namespace check.

  Ensures code does not open `namespace absl` as that violates Abseil’s compatibility guidelines.

- New abseil-redundant-strcat-calls check.

  Suggests removal of unnecessary calls to `absl::StrCat` when the result is being passed to another `absl::StrCat` or `absl::StrAppend`.

- New abseil-str-cat-append check.

  Flags uses of `absl::StrCat()` to append to a `std::string`. Suggests `absl::StrAppend()` should be used instead.

- New abseil-upgrade-duration-conversions check.

  Finds calls to `absl::Duration` arithmetic operators and factories whose argument needs an explicit cast to continue compiling after upcoming API changes.

- New bugprone-too-small-loop-variable check.

  Detects those `for` loops that have a loop variable with a “too small” type which means this type can’t represent all values which are part of the iteration range.

- New cppcoreguidelines-macro-usage check.

  Finds macro usage that is considered problematic because better language constructs exist for the task.

- New google-objc-function-naming check.

  Checks that function names in function declarations comply with the naming conventions described in the Google Objective-C Style Guide.

- New misc-non-private-member-variables-in-classes check.

  Finds classes that not only contain the data (non-static member variables), but also have logic (non-static member functions), and diagnoses all member variables that have any other scope other than `private`.

- New modernize-avoid-c-arrays check.

  Finds C-style array types and recommend to use `std::array<>` / `std::vector<>`.

- New modernize-concat-nested-namespaces check.

  Checks for uses of nested namespaces in the form of `namespace a { namespace b { ... }}` and offers change to syntax introduced in C++17 standard: `namespace a::b { ... }`.

- New modernize-deprecated-ios-base-aliases check.

  Detects usage of the deprecated member types of `std::ios_base` and replaces those that have a non-deprecated equivalent.

- New modernize-use-nodiscard check.

  Adds `[[nodiscard]]` attributes (introduced in C++17) to member functions to highlight at compile time which return values should not be ignored.

- New readability-const-return-type check.

  Checks for functions with a `const`-qualified return type and recommends removal of the `const` keyword.

- New readability-isolate-decl check.

  Detects local variable declarations declaring more than one variable and tries to refactor the code to one statement per declaration.

- New readability-magic-numbers check.

  Detects usage of magic numbers, numbers that are used as literals instead of introduced via constants or symbols.

- New readability-redundant-preprocessor check.

  Finds potentially redundant preprocessor directives.

- New readability-uppercase-literal-suffix check.

  Detects when the integral literal or floating point literal has non-uppercase suffix, and suggests to make the suffix uppercase. The list of destination suffixes can be optionally provided.

- New alias cert-dcl16-c to readability-uppercase-literal-suffix added.

- New alias cppcoreguidelines-avoid-c-arrays to modernize-avoid-c-arrays added.

- New alias cppcoreguidelines-non-private-member-variables-in-classes to misc-non-private-member-variables-in-classes added.

- New alias hicpp-avoid-c-arrays to modernize-avoid-c-arrays added.

- New alias hicpp-uppercase-literal-suffix to readability-uppercase-literal-suffix added.

- The cppcoreguidelines-narrowing-conversions check now detects more narrowing conversions: - integer to narrower signed integer (this is compiler implementation defined), - integer - floating point narrowing conversions, - floating point - integer narrowing conversions, - constants with narrowing conversions (even in ternary operator).

- The objc-property-declaration check now ignores the Acronyms and IncludeDefaultAcronyms options.

- The readability-redundant-smartptr-get check does not warn about calls inside macros anymore by default.

- The readability-uppercase-literal-suffix check does not warn about literal suffixes inside macros anymore by default.