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clang-analyzer

README.adoc

clang-analyzer

Introduction

This example shows how to call the Clang Static Analyzer to do static analysis using the scan-build tool.

The files included in this example are:

$ tree
.
├── CMakeLists.txt
├── subproject1
│   ├── CMakeLists.txt
│   └── main1.cpp
└── subproject2
    ├── CMakeLists.txt
    └── main2.cpp

Requirements

To run this example you must have clang analyzer and the scan-build tool installed. This can be installed on Ubuntu using the following command.

$ sudo apt-get install clang

It will result in the tool being available as:

$ scan-build-3.6

Concepts

scan-build

To run clang static analyzer you can use the tool scan-build to run the analyzer when you also run the compiler. This overrides the CC and CXX environment variables and replaces them with it’s own tools. To run it you can do

$ scan-build-3.6 cmake ..
$ scan-build-3.6 make

By default this will run the standard compiler for your platform, i.e. gcc on linux. However, if you want to override this you can change the command to:

$ scan-build-3.6 --use-cc=clang-3.6 --use-c++=clang++-3.6 -o ./scanbuildout/ make

scan-build output

scan-build will only output warnings during compile time and will also generate a list of HTML files which contain detailed analysis of the error.

$ cd scanbuildout/
$ tree
.
└── 2017-07-03-213514-3653-1
    ├── index.html
    ├── report-42eba1.html
    ├── scanview.css
    └── sorttable.js

1 directory, 4 files

By default these are output to /tmp/scanbuildout/{run folder}. You can change this using scan-build -o /output/folder.

Building the example

$ mkdir build

$ cd build/

$ scan-build-3.6 -o ./scanbuildout make
scan-build: Using '/usr/lib/llvm-3.6/bin/clang' for static analysis
make: *** No targets specified and no makefile found.  Stop.
scan-build: Removing directory '/data/code/clang-analyzer/build/scanbuildout/2017-07-03-211632-937-1' because it contains no reports.
scan-build: No bugs found.
devuser@91457fbfa423:/data/code/clang-analyzer/build$ scan-build-3.6 -o ./scanbuildout cmake ..
scan-build: Using '/usr/lib/llvm-3.6/bin/clang' for static analysis
-- The C compiler identification is GNU 5.4.0
-- The CXX compiler identification is GNU 5.4.0
-- Check for working C compiler: /usr/share/clang/scan-build-3.6/ccc-analyzer
-- Check for working C compiler: /usr/share/clang/scan-build-3.6/ccc-analyzer -- works
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Detecting C compile features
-- Detecting C compile features - done
-- Check for working CXX compiler: /usr/share/clang/scan-build-3.6/c++-analyzer
-- Check for working CXX compiler: /usr/share/clang/scan-build-3.6/c++-analyzer -- works
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- Found CPPCHECK: /usr/local/bin/cppcheck
cppcheck found. Use cppccheck-analysis targets to run it
-- Configuring done
-- Generating done
-- Build files have been written to: /data/code/clang-analyzer/build
scan-build: Removing directory '/data/code/clang-analyzer/build/scanbuildout/2017-07-03-211641-941-1' because it contains no reports.
scan-build: No bugs found.

$ $ scan-build-3.6 -o ./scanbuildout make
scan-build: Using '/usr/lib/llvm-3.6/bin/clang' for static analysis
Scanning dependencies of target subproject1
[ 25%] Building CXX object subproject1/CMakeFiles/subproject1.dir/main1.cpp.o
[ 50%] Linking CXX executable subproject1
[ 50%] Built target subproject1
Scanning dependencies of target subproject2
[ 75%] Building CXX object subproject2/CMakeFiles/subproject2.dir/main2.cpp.o
/data/code/clang-analyzer/subproject2/main2.cpp:7:17: warning: Dereference of null pointer (loaded from variable 'x')
   std::cout << *x << std::endl;
                ^~
1 warning generated.
[100%] Linking CXX executable subproject2
[100%] Built target subproject2
scan-build: 1 bug found.
scan-build: Run 'scan-view /data/code/clang-analyzer/build/scanbuildout/2017-07-03-211647-1172-1' to examine bug reports.

$ cd scanbuildout/
$ tree
.
└── 2017-07-03-213514-3653-1
    ├── index.html
    ├── report-42eba1.html
    ├── scanview.css
    └── sorttable.js

1 directory, 4 files