C99 finishing touches and testing

[jgarzik]

No description provided.

[Copilot]

Pull request overview

This PR completes several C99 conformance “finishing touches” in the cc (pcc) compiler crate, primarily around complex numbers, K&R-style function definitions, and switch/case handling edge cases, and adds broad integration test coverage to validate the implemented features.

Changes:

• Add __builtin_complex parsing/AST/IR support and wire up builtin <complex.h> and <iso646.h> headers.
• Extend parsing and IR linearization to handle K&R parameter declarations and Duff’s-device-style case labels inside nested statements.
• Add multiple “mega-tests” for C89/C99 lexical elements, declarations, expressions, types/keywords, translation limits, stdlib headers, complex arithmetic, and operator precedence/associativity.

Reviewed changes

Copilot reviewed 26 out of 26 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
cc/types.rs	Adds TypeTable::make_complex helper to map base float types to their complex equivalents.
cc/parse/parser.rs	Implements K&R (old-style) parameter declaration parsing between ) and {.
cc/parse/expression.rs	Adds parsing for __builtin_complex(real, imag).
cc/parse/ast.rs	Introduces ExprKind::BuiltinComplex AST node.
cc/kw.rs	Adds __builtin_complex keyword entry.
cc/ir/linearize_emit.rs	Adds helper to promote real scalars to complex temps for mixed complex arithmetic.
cc/ir/linearize.rs	Adds IR emission for BuiltinComplex and supports real↔complex promotion in complex binary ops.
cc/ir/linearize_stmt.rs	Improves complex initialization handling and extends switch-case collection/linearization for Duff’s device patterns.
cc/builtin_headers.rs	Registers builtin header text for complex.h and iso646.h.
cc/include/complex.h	Adds builtin <complex.h> header content (macro + prototypes).
cc/include/iso646.h	Adds builtin <iso646.h> header content (operator-spelling macros).
cc/tests/c99/*.rs, cc/tests/c89/*.rs, cc/tests/*/mod.rs	Adds/extends large integration tests exercising the new and existing C89/C99 features.
cc/doc/c99-checklist.md	Updates checklist status to reflect completion of many C99 items and adds N/A rationale.
cc/doc/TODO.md	Refactors/condenses TODO content (esp. C11 sections and optimization pipeline notes).
cc/README.md	Documents explicitly “will not implement” items (_Imaginary, trigraphs).