Unexpected insertion when using unordered_map and capacity equals to 4

[tanzby]

Describe the bug
The insertion of unordered_map does not work correctly under capacity=4.

Steps to reproduce
Change the n from 100 to 4 in examples/cuda/unordered_map.cu, compile and run this example code.

Expected behavior
the terminal should be:
The duplicate-free map of numbers contains 5 elements (5 expected) and the computed sums are (2, 4) ((10, 30) expected)

Actual behavior
the terminal actually shows:
The duplicate-free map of numbers contains 2 elements (5 expected) and the computed sums are (2, 4) ((10, 30) expected)

System (please complete the following information):

• OS: Ubuntu 20.04
• Compiler: GCC
• Backend: CUDA
• Library version: master

[tanzby]

@stotko Can you take a look? thanks!

[stotko]

Thanks for the report! This is indeed an issue for very low capacity sizes as the internal excess list is too small in this case. #414 fixes this issue.