https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70092
Bug ID: 70092
Summary: Enhance -Wunused-but-set-parameter when the parameter
is also read
Product: gcc
Version: 5.2.1
Status: UNCONFIRMED
Severity: enhancement
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: hadrien-gcc at psydk dot org
Target Milestone: ---
I found a bogus piece of code in a real program, here is a simplified version:
bool getValue(int value) {
value = 42;
value++;
return true;
}
The bug comes from the missing & in the parameter declaration, the fix is:
bool getValue(int& value) ...
I build with -Wall and -Wextra, and I was wondering why
-Wunused-but-set-parameter could not catch this error.
If I remove the "value++;" line, it triggers the warning as expected. If I put
back the line, of if I rewrite it "value = value + 1;", the warning disappears.
I think it would be helpful if -Wunused-but-set-parameter was able to catch
this pattern.
Command line:
g++ -fPIC -std=c++11 -Wall -Wextra *.cpp -o exe
g++ -v:
Using built-in specs.
COLLECT_GCC=g++
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-linux-gnu/5/lto-wrapper
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Ubuntu 5.2.1-22ubuntu2'
--with-bugurl=file:///usr/share/doc/gcc-5/README.Bugs
--enable-languages=c,ada,c++,java,go,d,fortran,objc,obj-c++ --prefix=/usr
--program-suffix=-5 --enable-shared --enable-linker-build-id
--libexecdir=/usr/lib --without-included-gettext --enable-threads=posix
--libdir=/usr/lib --enable-nls --with-sysroot=/ --enable-clocale=gnu
--enable-libstdcxx-debug --enable-libstdcxx-time=yes
--with-default-libstdcxx-abi=new --enable-gnu-unique-object
--disable-vtable-verify --enable-libmpx --enable-plugin --with-system-zlib
--disable-browser-plugin --enable-java-awt=gtk --enable-gtk-cairo
--with-java-home=/usr/lib/jvm/java-1.5.0-gcj-5-amd64/jre --enable-java-home
--with-jvm-root-dir=/usr/lib/jvm/java-1.5.0-gcj-5-amd64
--with-jvm-jar-dir=/usr/lib/jvm-exports/java-1.5.0-gcj-5-amd64
--with-arch-directory=amd64 --with-ecj-jar=/usr/share/java/eclipse-ecj.jar
--enable-objc-gc --enable-multiarch --disable-werror --with-arch-32=i686
--with-abi=m64 --with-multilib-list=m32,m64,mx32 --enable-multilib
--with-tune=generic --enable-checking=release --build=x86_64-linux-gnu
--host=x86_64-linux-gnu --target=x86_64-linux-gnu
Thread model: posix
gcc version 5.2.1 20151010 (Ubuntu 5.2.1-22ubuntu2)
