If I run the following code in the gdb debugger and type in print inFile, I get the message "incomplete type".
#include <fstream>
#include <iostream>
int main() {
std::ifstream inFile;
inFile.open("testFile.txt");
std::cout<<"In the debugger if I print the inFile variable at this point I get the incomplete type message";
inFile.close();
}
This makes it rather difficult to debug. Anyone knows what the reason for this might be?
This is how I compile the file:
g++ -g -std=c++11 main.cpp -o main
Here is the complete GDB output:
>> gdb main
GNU gdb (Ubuntu 7.11.1-0ubuntu1~16.5) 7.11.1
Copyright (C) 2016 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law. Type "show copying"
and "show warranty" for details.
This GDB was configured as "x86_64-linux-gnu".
Type "show configuration" for configuration details.
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>.
Find the GDB manual and other documentation resources online at:
<http://www.gnu.org/software/gdb/documentation/>.
For help, type "help".
Type "apropos word" to search for commands related to "word"...
Reading symbols from main...done.
(gdb) break main
Breakpoint 1 at 0x400ac2: file main.cpp, line 3.
(gdb) run
Starting program: ~/main
Breakpoint 1, main () at main.cpp:3
3 int main() {
(gdb) n
4 std::ifstream inFile;
(gdb)
5 inFile.open("testFile.txt");
(gdb) print inFile
$1 = <incomplete type>
(gdb)
I used the approach ks1322 described in his post and got the following message for
dpkg --list | grep libstdc++
ii libstdc++-5-dev:amd64 5.4.0-6ubuntu1~16.04.5 amd64 GNU Standard C++ Library v3 (development files)
ii libstdc++6:amd64 5.4.0-6ubuntu1~16.04.5 amd64 GNU Standard C++ Library v3
The
sudo apt-get install libstdc++
displays
libstdc++6 libstdc++6-5-dbg-m68k-cross
libstdc++6-4.7-dbg libstdc++6-5-dbg-mips64-cross
libstdc++6-4.7-dbg-armel-cross libstdc++6-5-dbg-mips64el-cross
libstdc++6-4.7-dbg-armhf-cross libstdc++6-5-dbg-mips-cross
libstdc++6-4.7-dev libstdc++6-5-dbg-mipsel-cross
libstdc++6-4.7-dev-armel-cross libstdc++6-5-dbg-powerpc-cross
libstdc++6-4.7-dev-armhf-cross libstdc++6-5-dbg-powerpcspe-cross
libstdc++6-4.7-doc libstdc++6-5-dbg-ppc64-cross
libstdc++6-4.7-pic libstdc++6-5-dbg-ppc64el-cross
libstdc++6-4.7-pic-armel-cross libstdc++6-5-dbg-s390x-cross
libstdc++6-4.7-pic-armhf-cross libstdc++6-5-dbg-sh4-cross
libstdc++6-4.8-dbg libstdc++6-5-dbg-sparc64-cross
libstdc++6-4.8-dbg-arm64-cross libstdc++6-alpha-cross
libstdc++6-4.8-dbg-armhf-cross libstdc++6-arm64-cross
libstdc++6-4.8-dbg-powerpc-cross libstdc++6-armel-cross
libstdc++6-4.8-dbg-ppc64el-cross libstdc++6-armhf-cross
libstdc++6-4.9-dbg libstdc++6-hppa-cross
libstdc++6-4.9-dbg-arm64-cross libstdc++6-m68k-cross
libstdc++6-4.9-dbg-armel-cross libstdc++6-mips64-cross
libstdc++6-4.9-dbg-armhf-cross libstdc++6-mips64el-cross
libstdc++6-4.9-dbg-powerpc-cross libstdc++6-mips-cross
libstdc++6-4.9-dbg-ppc64el-cross libstdc++6-mipsel-cross
libstdc++6-4.9-dbg-s390x-cross libstdc++6-powerpc-cross
libstdc++6-5-dbg libstdc++6-powerpcspe-cross
libstdc++6-5-dbg-alpha-cross libstdc++6-ppc64-cross
libstdc++6-5-dbg-arm64-cross libstdc++6-ppc64el-cross
libstdc++6-5-dbg-armel-cross libstdc++6-s390x-cross
libstdc++6-5-dbg-armhf-cross libstdc++6-sh4-cross
libstdc++6-5-dbg-hppa-cross libstdc++6-sparc64-cross
You need to install debug symbols for libstdc++ (this is where std::ifstream
resides). See here the similar issue for std::stringstream
:
That's caused by gdb not having debug information for your standard library. It's not enough to compile your program with -g, because it's the code in your standard library that defines those types. For example, if you're using gcc with a Debian based system, there's a -dbg version of libstdc++ that you can install. Example:
So you need to install this package libstdc++<your version>-dbg
with apt-get
:
sudo apt-get install libstdc++<your version>-dbg
Replace <your version>
with your version of libstdc++.
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