`inherited` previously parsed only as a statement, so calling an inherited
FUNCTION and using its result failed to parse:
Result := inherited Value() + 100; -> "Parse error: Expected expression"
This blocked the normal OOP pattern of an overriding function extending its
parent's result.
Adds the expression form alongside the existing statement form:
* uAST: new TInheritedCallExpr (sibling of TInheritedCallStmt) + CloneExpr case.
* uParser: tkInherited handled in ParseFactor (primary expression).
* uSemantic: AnalyseInheritedCallExpr resolves to the parent method (must be a
non-void function) and sets ResolvedType to the return type.
* Codegen: static (non-virtual) call to the parent slot, result returned as a
value. QBE EmitInheritedCallExpr; native EmitInheritedCallSeq (shared by the
statement and expression forms) leaves the result in %rax/%xmm0.
* uUnitInterfaceIO: 'inhc' encode/decode so inherited-expr in an inline method
body round-trips through the .bif unit-interface cache; bif-coverage.status
marks the two fields serialise (bif-coverage OK).
* docs/grammar.ebnf + docs/language-rationale.adoc updated (same commit).
Found by the e2e test-hardening sweep of the inheritance feature cluster.
Regression: TE2EMiscTests.TestRun_InheritedFunctionCall_InExpression covers a
value-returning inherited call and an inherited call with an argument, run on
BOTH backends via AssertRunsOnAll.
All three fixpoints (FIXPOINT_OK, NATIVE_FIXPOINT_OK, NATIVE_INTERNAL_OK) and
the full suite (3222 tests) pass.
74f71023da