Assignments to bit-fields yield results of bit-field type

[tautschnig]

Do not use the type of the assignment expression (which is the underlying type) to store the result.

Also fixes C pretty-printing of bit-field typed constants.

Issue was found by CSmith (test generated with random seed 1665747314).

• Each commit message has a non-empty body, explaining why the change was made.
• n/a Methods or procedures I have added are documented, following the guidelines provided in CODING_STANDARD.md.
• n/a The feature or user visible behaviour I have added or modified has been documented in the User Guide in doc/cprover-manual/
• Regression or unit tests are included, or existing tests cover the modified code (in this case I have detailed which ones those are in the commit message).
• n/a My commit message includes data points confirming performance improvements (if claimed).
• My PR is restricted to a single feature or bugfix.
• n/a White-space or formatting changes outside the feature-related changed lines are in commits of their own.

[codecov]

Codecov Report

Base: 78.01% // Head: 78.01% // Increases project coverage by +0.00% 🎉

Coverage data is based on head (623cde5) compared to base (ddf0fd2).
Patch coverage: 100.00% of modified lines in pull request are covered.

Additional details and impacted files

@@           Coverage Diff            @@
##           develop    #7270   +/-   ##
========================================
  Coverage    78.01%   78.01%           
========================================
  Files         1625     1625           
  Lines       187407   187411    +4     
========================================
+ Hits        146201   146205    +4     
  Misses       41206    41206           

Impacted Files	Coverage Δ
src/ansi-c/expr2c.cpp	67.30% <100.00%> (+0.03%)	⬆️
src/goto-programs/goto_clean_expr.cpp	99.02% <100.00%> (ø)
src/goto-programs/goto_convert_side_effect.cpp	94.50% <100.00%> (+0.02%)	⬆️

Help us with your feedback. Take ten seconds to tell us how you rate us. Have a feature suggestion? Share it here.

☔ View full report at Codecov.
📢 Do you have feedback about the report comment? Let us know in this issue.