Require a range constraint in ConstrainedScalarSubtypeSymbol

[Paebbels]

Changes

ConstrainedScalarSubtypeSymbol's range constraint is now mandatory.

VHDL's grammar leaves no state in which this class has no constraint:

subtype_indication ::= [ resolution_indication ] type_mark [ constraint ]
constraint         ::= range_constraint | array_constraint | record_constraint
range_constraint   ::= **range** range
range              ::= range_attribute_name | simple_expression direction simple_expression

The range keyword is always followed by a range, so a subtype indication is either a bare type mark — modelled as SimpleSubtypeSymbol — or a type mark with a range. There is integer and there is integer range 0 to 5, but no integer range.

• constraint loses its None default and is typed Range instead of Nullable[Range], in ScalarConstraint as well as in ConstrainedScalarSubtypeSymbol.
• The Constraint property returns Range.

Documentation

• ScalarConstraint states why the range is mandatory, citing the range_constraint rule.
• ConstrainedScalarSubtypeSymbol gained a second example for the range-attribute form, subtype index is natural range vector'range;, which is a RangeFromName referring to a RangeAttributeSymbol. That form was the reason the parameter was optional, and it is a range like any other.

Unit Tests

• test_ScalarConstraint_RangeIsMandatory and test_ConstrainedScalarSubtypeSymbol_withoutConstraint now assert that omitting the constraint raises a TypeError; previously both asserted that Constraint is None.
• test_ScalarConstraint_WithRangeAttribute covers the range-attribute form.

465 tests pass (was 464).

Notes

range <> — as in type matrix is array (natural range <>) of bit; — is an index_subtype_definition, not a subtype indication. ArrayType models it as a dimension (List[Range]), so it never reaches this class.

This is a breaking change, so the next release is a minor one: v0.39.0 rather than v0.38.1. #168 has to be retitled and its version bump adjusted once this is merged.

pyGHDL.dom needs a companion change. GetScalarConstrainedSubtypeFromNode passes None when GHDL reports the range constraint as an Attribute_Name, with a # TODO: Get actual range from AttributeName node?. Nothing raises, so this is not a crash — but Constraint would hold None in violation of its type. _Translate.py already builds exactly the right object one function further down (RangeFromName(node, RangeAttributeSymbol(node, GetName(node)))), so the fix is a few lines. Filed in the findings notebook.

[codacy-production]

Not up to standards ⛔

🔴 Issues 2 critical · 4 minor

Alerts:
⚠ 6 issues (≤ 0 issues of at least minor severity)

Results:
6 new issues

Category	Results
Documentation	4 minor
ErrorProne	2 critical

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🟢 Metrics 0 complexity · 0 duplication

Metric	Results
Complexity	0
Duplication	0

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🟢 Coverage 100.00% diff coverage · +0.00% coverage variation

Metric	Results
Coverage variation	✅ +0.00% coverage variation
Diff coverage	✅ 100.00% diff coverage

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Coverage variation details

	Coverable lines	Covered lines	Coverage
Common ancestor commit (6e8fca2)	5219	4641	88.93%
Head commit (d7c8157)	5219 (+0)	4641 (+0)	88.93% (+0.00%)

Coverage variation is the difference between the coverage for the head and common ancestor commits of the pull request branch: <coverage of head commit> - <coverage of common ancestor commit>

Diff coverage details

	Coverable lines	Covered lines	Diff coverage
Pull request (#172)	3	3	100.00%

Diff coverage is the percentage of lines that are covered by tests out of the coverable lines that the pull request added or modified: <covered lines added or modified>/<coverable lines added or modified> * 100%

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 87.14%. Comparing base (6e8fca2) to head (56d3299).
⚠️ Report is 3 commits behind head on dev.
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@           Coverage Diff           @@
##              dev     #172   +/-   ##
=======================================
  Coverage   87.14%   87.14%           
=======================================
  Files          24       24           
  Lines        5219     5219           
  Branches      446      446           
=======================================
  Hits         4548     4548           
  Misses        578      578           
  Partials       93       93           

Flag	Coverage Δ
unittests	87.14% <100.00%> (ø)

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[Paebbels]

/cc @domWalters

[Paebbels]

CI: 53 jobs succeeded, 9 skipped, 1 failed — run 30947957072. All unit-test jobs pass on every platform and Python version.

The one failure is PublishToGitHubPages / 📖 Merge multiple contents for publishing, and it is not related to this change:

Branch "claude/mandatory-scalar-constraint" is not allowed to deploy to github-pages due to environment protection rules.

The github-pages environment only accepts deployments from protected branches, so the job is rejected after one second, before any step runs. The same job failed identically on claude/dependency-updates (run 30947167380), which is now merged as #171. Filed as a finding.