Extra Clang Tools 3.9 Release Notes¶
Written by the LLVM Team
This document contains the release notes for the Extra Clang Tools, part of the Clang release 3.9. Here we describe the status of the Extra Clang Tools in some detail, including major improvements from the previous release and new feature work. For the general Clang release notes, see the Clang documentation. All LLVM releases may be downloaded from the LLVM releases web site.
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.
clang-include-fixer, a tool that provides an automated way of adding #include directives for missing symbols in one translation unit.
It aims to provide automated insertion of missing #includes with a single button press in an editor. Integration with Vim and a tool to generate the symbol index used by the tool are also part of this release. See the include-fixer documentation for more information.
clang-tidy‘s checks are constantly being improved to catch more issues, explain them more clearly, and provide more accurate fix-its for the issues identified. The improvements since the 3.8 release include:
New Boost module containing checks for issues with Boost library.
New boost-use-to-string check
Finds usages of boost::lexical_cast<std::string> and changes it to std::to_string.
New cert-env33-c check
Flags calls to system(), popen(), and _popen(), which execute a command processor.
New cert-err34-c check
Flags calls to string-to-number conversion functions that do not verify the validity of the conversion.
New cert-flp30-c check
Flags for loops where the induction expression has a floating-point type.
New cppcoreguidelines-interfaces-global-init check
Flags initializers of globals that access extern objects, and therefore can lead to order-of-initialization problems.
New cppcoreguidelines-pro-type-member-init check
Flags user-defined constructor definitions that do not initialize all builtin and pointer fields which leaves their memory in an undefined state.
New google-default-arguments check
Flags default arguments in virtual methods.
New misc-dangling-handle check
Detects dangling references in value handlers like std::experimental::string_view.
New misc-fold-init-type check
The check flags type mismatches in folds like std::accumulate that might result in loss of precision.
New misc-forward-declaration-namespace check
Checks if an unused forward declaration is in a wrong namespace.
New misc-misplaced-const check
Checks if a const qualifier is applied to a typedef to pointer type instead of the underlying pointee type.
New misc-misplaced-widening-cast check
Warns when there is a explicit redundant cast of a calculation result to a bigger type.
New misc-multiple-statement-macro check
Detect multiple statement macros that are used in unbraced conditionals.
New misc-pointer-and-integral-operation check
Warns about suspicious operations involving pointers and integral types.
New misc-redundant-expression check
Warns about redundant and equivalent expressions.
New misc-sizeof-expression check
Warns about incorrect uses of sizeof operator.
New misc-string-constructor check
Finds string constructors that are suspicious and probably errors.
New misc-string-literal-with-embedded-nul check
Warns about suspicious NUL character in string literals which may lead to truncation or invalid character escaping.
New misc-suspicious-missing-comma check
Warns about ‘probably’ missing comma in string literals initializer list.
New misc-suspicious-semicolon check
Finds most instances of stray semicolons that unexpectedly alter the meaning of the code.
New misc-suspicious-string-compare check
Find suspicious usage of runtime string comparison functions.
New misc-unconventional-assign-operator check replacing the misc-assign-operator-signature check.
Does not only checks for correct signature but also for correct return statements (returning *this)
New misc-unused-using-decls check
Finds unused using declarations.
New modernize-avoid-bind check
Finds uses of std::bind and replaces simple uses with lambdas.
New modernize-deprecated-headers check
Replaces C standard library headers with their C++ alternatives.
New modernize-make-shared check
Replaces creation of std::shared_ptr from new expression with call to std::make_shared.
New modernize-raw-string-literal check
Selectively replaces string literals containing escaped characters with raw string literals.
New modernize-use-bool-literals check
Finds integer literals which are cast to bool.
New modernize-use-emplace check
Finds calls that could be changed to emplace.
New modernize-use-using check
Finds typedefs and replaces it with usings.
New performance-faster-string-find check
Optimize calls to std::string::find() and friends when the needle passed is a single character string literal.
New performance-implicit-cast-in-loop check
Warns about range-based loop with a loop variable of const ref type where the type of the variable does not match the one returned by the iterator.
New performance-unnecessary-value-param check
Flags value parameter declarations of expensive to copy types that are copied for each invocation but it would suffice to pass them by const reference.
New readability-avoid-const-params-in-decls check
Warns about top-level const parameters in function declarations.
New readability-deleted-default check
Warns about defaulted constructors and assignment operators that are actually deleted.
Added support for enforcing the case of macro statements.
New readability-redundant-control-flow check
Looks for procedures (functions returning no value) with return statements at the end of the function. Such return statements are redundant.
New readability-redundant-string-init check
Finds unnecessary string initializations.
Finds static function and variable definitions in anonymous namespace.
- Crash when running on compile database with relative source files paths.
- Crash when running with the -fdelayed-template-parsing flag.
- The modernize-use-override check: incorrect fix-its placement around __declspec and other attributes.
The 3.8 release didn’t include release notes for clang-tidy. In the 3.8 release many new checks have been added to clang-tidy:
Checks enforcing certain rules of the CERT Secure Coding Standards:
Checks supporting the C++ Core Guidelines:
The functionality of the clang-modernize tool has been moved to the new modernize module in clang-tidy along with a few new checks:
- modernize-shrink-to-fit (renamed from readability-shrink-to-fit)
- modernize-use-override (renamed from misc-use-override)
New checks flagging various readability-related issues:
Updated cppcoreguidelines-pro-member-type-member-init check
This check now conforms to C++ Core Guidelines rule Type.6: Always Initialize a Member Variable. The check examines every record type where construction might result in an undefined memory state. These record types needing initialization have at least one default-initialized built-in, pointer, array or record type matching these criteria or a default-initialized direct base class of this kind.
The check has two complementary aspects:
- Ensure every constructor for a record type needing initialization value-initializes all members and direct bases via a combination of in-class initializers and the member initializer list.
- Value-initialize every non-member instance of a record type needing initialization that lacks a user-provided default constructor, e.g. a POD.