LCLint Version 1.4 MIT/LCS Distribution Site 7 October 1994 David Evans [email protected] Contents: 1. Overview 2. Changes from Version 1.3 3. Availability 4. References 5. Feedback and Mailing Lists 1. Overview LCLint is a lint-like tool for ANSI C. It can be used like a traditional lint to detect certain classes of C errors statically; if formal specifications are also supplied, it can do more powerful checking to detect inconsistencies between specifications and code. Without specifications, LCLint does many of the checks done by a traditional lint. It reports unused declarations, type inconsistencies, use-before-definition, unreachable code, ignored return values, execution paths with no return, likely infinite loops, and fall-through cases. It provides options for stricter type-checking than standard C (e.g., char and bool types can be treated as distinct from ints.). It does not do much of the portability checking (e.g., pointer alignment) done by typical lints. With partial specifications, written in the Larch interface language, LCL, LCLint does stronger checking. For example, a one-line specification file can declare a type as abstract; LCLint checks that the data abstraction barrier is maintained in clients of the type. This provides the advantages of data encapsulation, making programs easier to understand and maintain. Adding more specifications enables further checking, including the detection of: o inconsistent use of global variables o undocumented modification of client-visible state o inconsistent use of an uninitialized formal parameter or failure to initialize an actual parameter o macros specified as functions do not behave functionally LCLint can be customized to a particular coding style using command line flags. Stylized comments may be used to suppress messages and control checking at a local level. 2. Changes from Version 1.3 This list briefly describes the main changes between version 1.3 and version 1.4. For more details, see the User's Guide. Since some of these changes produce stricter checking, new errors may be programs which were checked using old versions of lclint. New Platforms: In addition to the original platforms (DEC Alpha AXP running OSF/1, DECstation running Ultrix, Sun workstation (Sparc) running Solaris 2, and Sun workstation (Sparc) running SunOS4.1/Solaris), lclint now supports PC running linux and SGIs runing IRIX. It has also been compiled sucessfully on several other platforms. Source code is freely available if you are interested in building a version for some other platform. Changes: o must modify checking (off in default mode, use +mustmod) reports instances where a specified modification is not detected in the implementation. o rep exposure (off in default mode, use +repexpose, +retexpose, +assignexpose) reports instances where an abstract representation is exposed by either: 1. returning a pointer or mutable object which is a component of an abstract representation (+retexpose) 2. assigning a component of an abstract type to a pointer or mutable object to which the client has access (+assignexpose) (+repexpose turns both on) o return aliases (off in default mode, use +retalias) reports instances where the return value is an alias to a parameter or global o support for stylized iterators see User's Guide, section 1.5. o checking unspecified macros as functions (off in default mode, use +allmacros) prevents expansion of all parameterized macros and checks them as functions of unknown type. When using +allmacros, a single macro definition can be preceded by /*@notfunction*/ to force its expansion and prevent it being checked as a function. o printf, scanf (and variants) format arguments checking checks types of additional arguments to printf and scanf calls if the format string is known at compile time. o boolean comparisons (on in default mode, use -boolcompare to suppress) reports instances where bool values are compared (dangerous since C allows multiple true values) o checks mode new mode with checking between standard and strict o .lclintrc the .lclintrc file in the current directory (if it exists) is now read, after the ~/.lclintrc file. Bug fixes: As far as I know, all known bugs in version 1.3 have been fixed. If you encountered a bug in version 1.3 that has not been fixed in version 1.4, please send a bug report to [email protected] o grammar parse problems o include file semantics in different directories o abstract bool (+bool) now handles abstract access correctly 3. Availability LCLint is available by anonymous ftp from larch.lcs.mit.edu in pub/Larch/lclint/. Installation pacakages are available for the following platforms: o DEC Alpha AXP running OSF/1 (alpha) o DECstation running Ultrix (decmips) o Sun workstation (Sparc) running Solaris 2 (solaris2) o Sun workstation (Sparc) running SunOS4.1/Solaris 1 (sun4) o PC running linux (linux) o SGIs runing IRIX (irix) The easiest, most complete way is to pick up one file containing everything you need to run lclint. These are called: lclint
. .tar.Z Each installation package includes the lclint executable, library files, manual pages, user's guide, an emacs mode, and a few samples. Packages may be uncompressed using gunzip. For more information on installation packages, read the file pub/Larch/lclint/INSTALL. (This file is included in the installation packages also.) 4. References More information on LCLint is available in "Using Specifications to Check Source Code", David Evans, MIT/LCS/TR-628. Available as hard-copy from MIT Laboratory of Computer Science, Reading Room, 545 Technology Square, Cambridge, MA 02139. Available electronically as ftp://ftp.sds.lcs.mit.edu/pub/lclint/tr.ps.Z. A web page on the Larch project is available at URL http://larch-www.lcs.mit.edu:8001/larch/ A web page for LCLint specifically, including an html version of the User's Guide, is available at URL http://www.sds.lcs.mit.edu/lclint.html There are two mailing lists associated with LCLint: [email protected] Reserved for announcements of new releases and bug fixes. [email protected] Informal discussions on the use and development of lclint. Send a (human-readable) message to [email protected] to subscribe to a list. ------------------------------------------------------------------------- LCLint is the result of a joint R&D project (Larch) involving Digital Equipment Corporation and MIT. It was written in ANSI C by David Evans, building on an LCL checker written by Yang Meng Tan, which in turn built on work done by Gary Feldman, Steve Garland, and Joe Wild. Thanks to Chris Flatters for producing the Solaris port and Thomas G. McWilliams for the linux port. Many others have reported bugs or provided useful suggestions for improving LCLint.