varinit_examples

varinit_examples — variable initializers, completed (Enhancement-43)

Demonstrates declaration initializers (real x = 2.5;) — evaluated once at the start of the simulation, LRM semantics — using the committed openvaf-r and ngspice-46.

What was broken

Scalar initializers (including parameter-dependent constant expressions and strings) already worked, with correct init-once semantics for event-updated state. Three defects remained:

1. Array declaration initializers were rejected — real x[0:2] = '{1.0, 2.0, 4.0}; failed with "expected real value but found real[0:3] value", repeated once per element (each expanded element variable checked the whole aggregate against its scalar type).
2. An analog-function argument without a type declaration crashed the compiler — input v; with no real v; line yielded Type::Err, which hit unreachable!("unknown cast found Real -> Err") at the first cast.
3. A wrong-arity initializer crashed the compiler — real x[0:2] = '{1.0, 2.0}; (and the array-parameter equivalent) lowered the missing leaves as Expr::Missing and died with "invalid HIR: Missing".

E-43 wires array-variable initializers through the same split-literal machinery as array parameters (each element carries its flat row-major array_index and picks its leaf), defaults untyped function arguments to real (matching the untyped return type), and adds a named arity diagnostic covering variables and parameters.

Run

python3 verify_varinit.py

Checks (ALL PASS, exact): scalar/param-dependent/string inits, y = 2*p+1 tracking a p override; init-once counter starting at 10 and counting crossings; 1-D real + integer, 2-D, 3-D arrays and parameter-dependent leaves (66 + 4·s) tracking an s override; an array element initialized to 100 and event-updated from there; function-local scalar + array initializers with an untyped argument (used to ICE); and four wrong-arity forms rejected with array initializer for 'x' has N elements but the array has M instead of a crash.