https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98919
Bug ID: 98919
Summary: auto declaration of multiple variables allows
inconsistent types
Product: gcc
Version: 10.2.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: stephan.oostv...@nextlevel-electronics.com
Target Milestone: ---
Created attachment 50111
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=50111&action=edit
Preprocessed file
gcc version: 10.2.1 20201125 (Red Hat 10.2.1-9) (GCC)
System version: Fedora 33 x86_64
Compile command: gcc -v -save-temps -std=c++17 -O3 -Wall -Wextra -Wpedantic -o
test test.cpp
auto allows to declare two different types in a single statement when used in a
templated context.
See also https://godbolt.org/z/brWYjP as an example.
Compiler output:
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/libexec/gcc/x86_64-redhat-linux/10/lto-wrapper
OFFLOAD_TARGET_NAMES=nvptx-none
OFFLOAD_TARGET_DEFAULT=1
Target: x86_64-redhat-linux
Configured with: ../configure --enable-bootstrap
--enable-languages=c,c++,fortran,objc,obj-c++,ada,go,d,lto --prefix=/usr
--mandir=/usr/share/man --infodir=/usr/share/info
--with-bugurl=http://bugzilla.redhat.com/bugzilla --enable-shared
--enable-threads=posix --enable-checking=release --enable-multilib
--with-system-zlib --enable-__cxa_atexit --disable-libunwind-exceptions
--enable-gnu-unique-object --enable-linker-build-id
--with-gcc-major-version-only --with-linker-hash-style=gnu --enable-plugin
--enable-initfini-array --with-isl --enable-offload-targets=nvptx-none
--without-cuda-driver --enable-gnu-indirect-function --enable-cet
--with-tune=generic --with-arch_32=i686 --build=x86_64-redhat-linux
Thread model: posix
Supported LTO compression algorithms: zlib zstd
gcc version 10.2.1 20201125 (Red Hat 10.2.1-9) (GCC)
COLLECT_GCC_OPTIONS='-v' '-save-temps' '-std=c++17' '-O3' '-Wall' '-Wextra'
'-Wpedantic' '-o' 'test' '-mtune=generic' '-march=x86-64'
/usr/libexec/gcc/x86_64-redhat-linux/10/cc1plus -E -quiet -v -D_GNU_SOURCE
test.cpp -mtune=generic -march=x86-64 -std=c++17 -Wall -Wextra -Wpedantic -O3
-fpch-preprocess -o test.ii
ignoring nonexistent directory
"/usr/lib/gcc/x86_64-redhat-linux/10/include-fixed"
ignoring nonexistent directory
"/usr/lib/gcc/x86_64-redhat-linux/10/../../../../x86_64-redhat-linux/include"
#include "..." search starts here:
#include <...> search starts here:
/usr/lib/gcc/x86_64-redhat-linux/10/../../../../include/c++/10
/usr/lib/gcc/x86_64-redhat-linux/10/../../../../include/c++/10/x86_64-redhat-linux
/usr/lib/gcc/x86_64-redhat-linux/10/../../../../include/c++/10/backward
/usr/lib/gcc/x86_64-redhat-linux/10/include
/usr/local/include
/usr/include
End of search list.
COLLECT_GCC_OPTIONS='-v' '-save-temps' '-std=c++17' '-O3' '-Wall' '-Wextra'
'-Wpedantic' '-o' 'test' '-mtune=generic' '-march=x86-64'
/usr/libexec/gcc/x86_64-redhat-linux/10/cc1plus -fpreprocessed test.ii -quiet
-dumpbase test.cpp -mtune=generic -march=x86-64 -auxbase test -O3 -Wall -Wextra
-Wpedantic -std=c++17 -version -o test.s
GNU C++17 (GCC) version 10.2.1 20201125 (Red Hat 10.2.1-9)
(x86_64-redhat-linux)
compiled by GNU C version 10.2.1 20201125 (Red Hat 10.2.1-9), GMP
version 6.2.0, MPFR version 4.1.0, MPC version 1.1.0, isl version
isl-0.16.1-GMP
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
GNU C++17 (GCC) version 10.2.1 20201125 (Red Hat 10.2.1-9)
(x86_64-redhat-linux)
compiled by GNU C version 10.2.1 20201125 (Red Hat 10.2.1-9), GMP
version 6.2.0, MPFR version 4.1.0, MPC version 1.1.0, isl version
isl-0.16.1-GMP
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
Compiler executable checksum: 9e47728dd41983b7aeec830bfccf6d2e
test.cpp: In instantiation of ‘constexpr void test() [with long unsigned int N
= 42]’:
test.cpp:15:14: required from here
test.cpp:11:10: warning: unused variable ‘aIt’ [-Wunused-variable]
11 | auto aIt = begin(a), bIt = begin(b);
| ^~~
test.cpp:11:26: warning: unused variable ‘bIt’ [-Wunused-variable]
11 | auto aIt = begin(a), bIt = begin(b);
| ^~~
COLLECT_GCC_OPTIONS='-v' '-save-temps' '-std=c++17' '-O3' '-Wall' '-Wextra'
'-Wpedantic' '-o' 'test' '-mtune=generic' '-march=x86-64'
as -v --64 -o test.o test.s
GNU assembler version 2.35 (x86_64-redhat-linux) using BFD version version
2.35-18.fc33
COMPILER_PATH=/usr/libexec/gcc/x86_64-redhat-linux/10/:/usr/libexec/gcc/x86_64-redhat-linux/10/:/usr/libexec/gcc/x86_64-redhat-linux/:/usr/lib/gcc/x86_64-redhat-linux/10/:/usr/lib/gcc/x86_64-redhat-linux/
LIBRARY_PATH=/usr/lib/gcc/x86_64-redhat-linux/10/:/usr/lib/gcc/x86_64-redhat-linux/10/../../../../lib64/:/lib/../lib64/:/usr/lib/../lib64/:/usr/lib/gcc/x86_64-redhat-linux/10/../../../:/lib/:/usr/lib/
COLLECT_GCC_OPTIONS='-v' '-save-temps' '-std=c++17' '-O3' '-Wall' '-Wextra'
'-Wpedantic' '-o' 'test' '-mtune=generic' '-march=x86-64'
/usr/libexec/gcc/x86_64-redhat-linux/10/collect2 -plugin
/usr/libexec/gcc/x86_64-redhat-linux/10/liblto_plugin.so
-plugin-opt=/usr/libexec/gcc/x86_64-redhat-linux/10/lto-wrapper
-plugin-opt=-fresolution=test.res -plugin-opt=-pass-through=-lgcc
-plugin-opt=-pass-through=-lgcc_s -plugin-opt=-pass-through=-lc
-plugin-opt=-pass-through=-lgcc -plugin-opt=-pass-through=-lgcc_s --build-id
--no-add-needed --eh-frame-hdr --hash-style=gnu -m elf_x86_64 -dynamic-linker
/lib64/ld-linux-x86-64.so.2 -o test
/usr/lib/gcc/x86_64-redhat-linux/10/../../../../lib64/crt1.o
/usr/lib/gcc/x86_64-redhat-linux/10/../../../../lib64/crti.o
/usr/lib/gcc/x86_64-redhat-linux/10/crtbegin.o
-L/usr/lib/gcc/x86_64-redhat-linux/10
-L/usr/lib/gcc/x86_64-redhat-linux/10/../../../../lib64 -L/lib/../lib64
-L/usr/lib/../lib64 -L/usr/lib/gcc/x86_64-redhat-linux/10/../../.. test.o -lgcc
--push-state --as-needed -lgcc_s --pop-state -lc -lgcc --push-state --as-needed
-lgcc_s --pop-state /usr/lib/gcc/x86_64-redhat-linux/10/crtend.o
/usr/lib/gcc/x86_64-redhat-linux/10/../../../../lib64/crtn.o
COLLECT_GCC_OPTIONS='-v' '-save-temps' '-std=c++17' '-O3' '-Wall' '-Wextra'
'-Wpedantic' '-o' 'test' '-mtune=generic' '-march=x86-64'
