Base class with pure virtual method must have inline constructor

Example of behaviour:

This links:

 class A {
 public:
  A() {}
  virtual void foo() = 0;
 };

 class B : public A {
 public:
  void foo() {}
 };

This does not link:

 class A {
 public:
  A();
  virtual void foo() = 0;
 };

 A::A() {}

 class B : public A {
 public:
  void foo() {}
 };

When instantianing B object.

Linker flags:
-mcpu=cortex-m3 -mthumb -Og -fmessage-length=0 -fsigned-char -ffunction-sections -fdata-sections -ffreestanding -pedantic -Wunused -Wuninitialized -Wall -Wextra -g3 -Xlinker --gc-sections --specs=nano.specs

Linking exits with an error:

c:/eclipsearm/toolchain/5_2-2015q4/bin/../lib/gcc/arm-none-eabi/5.2.1/../../../../arm-none-eabi/lib/armv7-m\libg_nano.a(lib_a-abort.o): In function `abort':
abort.c:(.text.abort+0xa): undefined reference to `_exit'
c:/eclipsearm/toolchain/5_2-2015q4/bin/../lib/gcc/arm-none-eabi/5.2.1/../../../../arm-none-eabi/lib/armv7-m\libg_nano.a(lib_a-sbrkr.o): In function `_sbrk_r':
sbrkr.c:(.text._sbrk_r+0xc): undefined reference to `_sbrk'
c:/eclipsearm/toolchain/5_2-2015q4/bin/../lib/gcc/arm-none-eabi/5.2.1/../../../../arm-none-eabi/lib/armv7-m\libg_nano.a(lib_a-signalr.o): In function `_kill_r':
signalr.c:(.text._kill_r+0xe): undefined reference to `_kill'
c:/eclipsearm/toolchain/5_2-2015q4/bin/../lib/gcc/arm-none-eabi/5.2.1/../../../../arm-none-eabi/lib/armv7-m\libg_nano.a(lib_a-signalr.o): In function `_getpid_r':
signalr.c:(.text._getpid_r+0x0): undefined reference to `_getpid'
c:/eclipsearm/toolchain/5_2-2015q4/bin/../lib/gcc/arm-none-eabi/5.2.1/../../../../arm-none-eabi/lib/armv7-m\libg_nano.a(lib_a-writer.o): In function `_write_r':
writer.c:(.text._write_r+0x10): undefined reference to `_write'
c:/eclipsearm/toolchain/5_2-2015q4/bin/../lib/gcc/arm-none-eabi/5.2.1/../../../../arm-none-eabi/lib/armv7-m\libg_nano.a(lib_a-closer.o): In function `_close_r':
closer.c:(.text._close_r+0xc): undefined reference to `_close'
c:/eclipsearm/toolchain/5_2-2015q4/bin/../lib/gcc/arm-none-eabi/5.2.1/../../../../arm-none-eabi/lib/armv7-m\libg_nano.a(lib_a-fstatr.o): In function `_fstat_r':
fstatr.c:(.text._fstat_r+0xe): undefined reference to `_fstat'
c:/eclipsearm/toolchain/5_2-2015q4/bin/../lib/gcc/arm-none-eabi/5.2.1/../../../../arm-none-eabi/lib/armv7-m\libg_nano.a(lib_a-isattyr.o): In function `_isatty_r':
isattyr.c:(.text._isatty_r+0xc): undefined reference to `_isatty'
c:/eclipsearm/toolchain/5_2-2015q4/bin/../lib/gcc/arm-none-eabi/5.2.1/../../../../arm-none-eabi/lib/armv7-m\libg_nano.a(lib_a-lseekr.o): In function `_lseek_r':
lseekr.c:(.text._lseek_r+0x10): undefined reference to `_lseek'
c:/eclipsearm/toolchain/5_2-2015q4/bin/../lib/gcc/arm-none-eabi/5.2.1/../../../../arm-none-eabi/lib/armv7-m\libg_nano.a(lib_a-readr.o): In function `_read_r':
readr.c:(.text._read_r+0x10): undefined reference to `_read'
collect2.exe: error: ld returned 1 exit status

Toolchain version:
arm-none-eabi-gcc.exe (GNU Tools for ARM Embedded Processors) 5.2.1 20151202 (release) [ARM/embedded-5-branch revision 231848]