Add empty_namespacet for unit tests

[tautschnig]

Introduce empty_namespacet, a namespacet subclass that self-contains an empty symbol_tablet member. This avoids the boilerplate of declaring a symbol_tablet and namespacet in every test that doesn't actually populate the symbol table.

Follows the same pattern as the existing null_message_handler in testing-utils.

Co-authored-by: Kiro kiro-agent@users.noreply.github.com

• Each commit message has a non-empty body, explaining why the change was made.
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• 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).
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• 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

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 80.54%. Comparing base (808dae2) to head (5645a21).

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #8996      +/-   ##
===========================================
- Coverage    80.55%   80.54%   -0.02%     
===========================================
  Files         1707     1708       +1     
  Lines       189051   188897     -154     
  Branches        73       73              
===========================================
- Hits        152299   152148     -151     
+ Misses       36752    36749       -3     

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[Copilot]

Pull request overview

Note

Copilot was unable to run its full agentic suite in this review.

Adds a reusable empty_namespacet for unit tests so callers can use a shared empty namespacet without repeatedly declaring a symbol_tablet + namespacet.

Changes:

• Introduced unit/testing-utils/empty_namespace.{h,cpp} and wired it into the unit testing-utils build.
• Updated many unit tests to use empty_namespace instead of locally constructing empty symbol tables/namespaces.
• Adjusted test module dependencies where needed.

Reviewed changes

Copilot reviewed 67 out of 67 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
unit/util/std_expr.cpp	Replaces local symbol_tablet/namespacet boilerplate with empty_namespace.
unit/util/simplify_expr.cpp	Uses empty_namespace for simplify-related unit tests.
unit/util/pointer_offset_size.cpp	Uses empty_namespace for namespace parameter in tests.
unit/util/lower_byte_operators.cpp	Uses empty_namespace instead of local namespace construction.
unit/util/interval/subtract.cpp	Removes unused local namespace boilerplate and includes empty_namespace.
unit/util/interval/multiply.cpp	Removes unused local namespace boilerplate and includes empty_namespace.
unit/util/interval/modulo.cpp	Removes unused local namespace boilerplate and includes empty_namespace.
unit/util/interval/get_extreme.cpp	Uses empty_namespace for simplify/namespace-dependent operations.
unit/util/interval/comparisons.cpp	Removes unused local namespace boilerplate and includes empty_namespace.
unit/util/interval/add.cpp	Removes unused local namespace boilerplate and includes empty_namespace.
unit/util/bitvector_expr.cpp	Uses empty_namespace for boolbvt construction in tests.
unit/testing-utils/empty_namespace.h	Introduces empty_namespacet and declares global empty_namespace.
unit/testing-utils/empty_namespace.cpp	Defines the global empty_namespace instance.
unit/testing-utils/Makefile	Adds empty_namespace.cpp to testing-utils build inputs.
unit/solvers/strings/string_refinement/string_refinement.cpp	Uses empty_namespace for string_refinement test environment.
unit/solvers/strings/string_format_builtin_function/length_of_decimal_int.cpp	Uses empty_namespace instead of local namespacet.
unit/solvers/strings/string_format_builtin_function/length_for_format_specifier.cpp	Uses empty_namespace instead of local namespacet.
unit/solvers/strings/string_constraint_generator_valueof/is_digit_with_radix.cpp	Uses empty_namespace for simplify/namespace usage.
unit/solvers/strings/string_constraint_generator_valueof/get_numeric_value_from_character.cpp	Uses empty_namespace for simplify/namespace usage.
unit/solvers/smt2_incremental/object_tracking.cpp	Uses empty_namespace in object tracking tests.
unit/solvers/smt2_incremental/convert_expr_to_smt.cpp	Uses empty_namespace for object tracking and conversions in tests.
unit/solvers/prop/bdd_expr.cpp	Removes local namespace boilerplate and includes empty_namespace.
unit/solvers/flattening/boolbv_update_bit.cpp	Uses empty_namespace for boolbvt construction.
unit/solvers/flattening/boolbv_onehot.cpp	Uses empty_namespace for boolbvt construction.
unit/solvers/flattening/boolbv_enumeration.cpp	Uses empty_namespace for boolbvt construction.
unit/solvers/flattening/boolbv.cpp	Uses empty_namespace for boolbvt construction.
unit/solvers/bdd/miniBDD/module_dependencies.txt	Adds flattening dependency to match updated includes/usage.
unit/solvers/bdd/miniBDD/miniBDD.cpp	Uses empty_namespace for boolbvt construction and related logic.
unit/goto-symex/shadow_memory_util.cpp	Uses empty_namespace when calling helpers requiring namespacet.
unit/goto-symex/is_constant.cpp	Uses empty_namespace for namespace parameter.
unit/goto-programs/xml_expr.cpp	Uses empty_namespace for XML conversion requiring namespacet.
unit/goto-programs/goto_trace_output.cpp	Uses empty_namespace for trace output requiring namespacet.
unit/ansi-c/expr2c.cpp	Uses empty_namespace instead of temporary namespacet{symbol_tablet{}}.
unit/analyses/variable-sensitivity/variable_sensitivity_test_helpers.cpp	Uses empty_namespace for from_expr in helper formatting.
unit/analyses/variable-sensitivity/variable_sensitivity_domain/to_predicate.cpp	Uses empty_namespace in predicate tests.
unit/analyses/variable-sensitivity/value_set_pointer_abstract_object/to_predicate.cpp	Uses empty_namespace in predicate tests.
unit/analyses/variable-sensitivity/value_set_abstract_object/widening_merge.cpp	Uses empty_namespace in merge tests.
unit/analyses/variable-sensitivity/value_set_abstract_object/to_predicate.cpp	Uses empty_namespace in predicate tests.
unit/analyses/variable-sensitivity/value_set_abstract_object/merge.cpp	Uses empty_namespace in merge tests.
unit/analyses/variable-sensitivity/value_set_abstract_object/meet.cpp	Uses empty_namespace in meet tests.
unit/analyses/variable-sensitivity/value_set_abstract_object/extremes-go-top.cpp	Uses empty_namespace in extremes/top tests.
unit/analyses/variable-sensitivity/value_set_abstract_object/compacting.cpp	Uses empty_namespace in compacting tests.
unit/analyses/variable-sensitivity/value_expression_evaluation/expression_evaluation.cpp	Uses empty_namespace in expression evaluation tests.
unit/analyses/variable-sensitivity/value_expression_evaluation/assume_prune.cpp	Uses empty_namespace in assume/prune tests.
unit/analyses/variable-sensitivity/value_expression_evaluation/assume.cpp	Uses empty_namespace in assume tests.
unit/analyses/variable-sensitivity/interval_abstract_value/widening_merge.cpp	Uses empty_namespace in widening merge tests.
unit/analyses/variable-sensitivity/interval_abstract_value/to_predicate.cpp	Uses empty_namespace in predicate tests.
unit/analyses/variable-sensitivity/interval_abstract_value/merge.cpp	Uses empty_namespace in merge tests.
unit/analyses/variable-sensitivity/interval_abstract_value/meet.cpp	Uses empty_namespace in meet tests.
unit/analyses/variable-sensitivity/interval_abstract_value/extremes-go-top.cpp	Uses empty_namespace in extremes/top tests.
unit/analyses/variable-sensitivity/full_struct_abstract_object/to_predicate.cpp	Uses empty_namespace in predicate tests.
unit/analyses/variable-sensitivity/full_struct_abstract_object/merge.cpp	Uses empty_namespace in merge tests.
unit/analyses/variable-sensitivity/full_array_abstract_object/to_predicate.cpp	Uses empty_namespace in predicate tests.
unit/analyses/variable-sensitivity/full_array_abstract_object/merge.cpp	Uses empty_namespace in merge tests.
unit/analyses/variable-sensitivity/full_array_abstract_object/maximum_length.cpp	Uses empty_namespace in maximum length tests.
unit/analyses/variable-sensitivity/eval-member-access.cpp	Uses empty_namespace in member access evaluation tests.
unit/analyses/variable-sensitivity/constant_pointer_abstract_object/to_predicate.cpp	Uses empty_namespace in predicate tests.
unit/analyses/variable-sensitivity/constant_abstract_value/to_predicate.cpp	Uses empty_namespace in predicate tests.
unit/analyses/variable-sensitivity/constant_abstract_value/merge.cpp	Uses empty_namespace in merge tests.
unit/analyses/variable-sensitivity/constant_abstract_value/meet.cpp	Uses empty_namespace in meet tests.
unit/analyses/variable-sensitivity/abstract_object/merge.cpp	Uses empty_namespace in merge tests.
unit/analyses/variable-sensitivity/abstract_object/index_range.cpp	Uses empty_namespace in index range tests.
unit/analyses/variable-sensitivity/abstract_environment/to_predicate.cpp	Uses empty_namespace in environment predicate tests.
unit/analyses/does_remove_const/is_type_at_least_as_const_as.cpp	Removes local namespace boilerplate and includes empty_namespace.
unit/analyses/does_remove_const/does_type_preserve_const_correctness.cpp	Removes local namespace boilerplate and includes empty_namespace.
unit/analyses/does_remove_const/does_expr_lose_const.cpp	Removes local namespace boilerplate and includes empty_namespace.
unit/analyses/ai/ai_simplify_lhs.cpp	Uses empty_namespace in AI simplify LHS tests.

Comments suppressed due to low confidence (3)

unit/testing-utils/empty_namespace.h:1

• namespacet (base) is constructed before symbol_table (member). Passing symbol_table into the base-class constructor before the member is constructed can lead to undefined behavior if namespacet touches the referenced symbol table during its construction. Fix by ensuring the symbol table is constructed before the namespacet base (e.g., use the base-from-member pattern via private inheritance from symbol_tablet, or store a namespacet member instead of inheriting).
  unit/testing-utils/empty_namespace.h:1
• As written, the compiler-generated copy/move operations for empty_namespacet are very likely to yield a broken object (the namespacet base will copy its internal references/pointers and keep referring to the source object's symbol table, while the destination has its own symbol_table member). This can produce dangling references after the source is destroyed. Make empty_namespacet non-copyable/non-movable (delete copy/move ctor and assignment), or implement them so the namespacet base is rebound to the destination's symbol table.
  unit/testing-utils/empty_namespace.h:1
• A global empty_namespace introduces a potential static-initialization-order dependency if any other global initializer in the unit test binary uses it. To avoid this class of issues, consider providing an accessor (e.g., a function returning a reference to a function-local static instance) and updating call sites to use that accessor.

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