Assert codegen

[0xGeorgii]

Closes #195

[Copilot]

Pull request overview

Implements WebAssembly codegen for the assert statement, replacing the previous todo!() panic with a trap-on-false sequence (<cond>; i32.eqz; if; unreachable; end). Also improves the type-checker diagnostic for assert <non-bool> by introducing a dedicated TypeMismatchContext::Assert and refactoring the shared bool-condition validation into a helper that points at the offending expression rather than the enclosing statement.

Changes:

• Lower Stmt::Assert in Compiler::lower_statement via a new lower_assert_statement helper guarded by cov_mark.
• Add TypeMismatchContext::Assert and extract a validate_bool_expression helper to deduplicate bool checks across if / loop / assert, with error location anchored on the expression.
• Add golden + execution + Soroban-compat tests and extend type-checker coverage tests for assert.

Reviewed changes

Copilot reviewed 9 out of 10 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
core/wasm-codegen/src/compiler.rs	Implements lower_assert_statement and wires Stmt::Assert to it.
core/type-checker/src/type_checker.rs	Refactors bool-condition checks to a shared helper; routes Assert through it with Assert context.
core/type-checker/src/errors.rs	Adds TypeMismatchContext::Assert variant and Display branch; extends Display tests.
tests/src/codegen/wasm/base.rs	Adds golden, runtime trap/ok, Soroban-accept, and regen-fixture tests for assert.
tests/src/codegen/wasm/negative.rs	Removes obsolete "assert is unimplemented" negative tests.
tests/src/type_checker/coverage.rs	Updates if/assert non-bool diagnostics expectations and adds positive/negative assert cases.
tests/test_data/codegen/wasm/base/assert/assert.inf	New .inf fixture covering 12 assert scenarios.
tests/test_data/codegen/wasm/base/assert/assert.wat	Expected WAT for the fixture.
CHANGELOG.md	Documents the codegen and type-checker changes.

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[codecov]

Codecov Report

❌ Patch coverage is 98.38710% with 1 line in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
core/type-checker/src/type_checker.rs	96.55%	1 Missing ⚠️

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