struct compound literal initialization by lorettayao · Pull Request #302 · sysprog21/shecc

lorettayao · 2025-09-28T05:44:19Z

This PR is a work-in-progress for issue #299.

Fixes the offset bug in compound literal initialization by
adjusting the source address by +4 bytes in parser.c.
Verified with simple test: x=10, y=20, z=30 now works.
Not final — needs feedback and further investigation.

Summary by cubic

Fix struct compound literal initialization in the parser so fields are assigned correctly instead of being shifted. Adds explicit brace-initializer emission and corrects assignment handling, addressing issue #299.

Bug Fixes
- Parse (struct/union T){...} and typedef structs, allocating a temp struct and writing each field.
- Add emit_struct_brace_initializer to compute field addresses and write values with correct sizes.
- On assignment from a struct literal, copy from source address +4 in 4-byte chunks to avoid the offset bug.

jserv

Consolidate git commit messages by enforcing the rules specified by How to Write a Git Commit Message carefully
Don't leave dead code
Don't mention your name (loretta) in code

jserv

Rebase the latest master branch.

jserv

Always minimize the necessary changes.

jserv

Minimize the necessary changes.

jserv

Check https://github.com/sysprog21/shecc/blob/master/CONTRIBUTING.md carefully and enforce the rules.

sysprog21#299)

Investigated the bug where compound literals like (struct point){10, 20, 30} produced shifted field values (e.g., x got garbage, y=10, z=20). Added a temporary fix by adjusting the source address +4 bytes in parser.c. Tested with simple cases: x=10, y=20, z=30. This is an experimental patch; needs review for design correctness. Refs: sysprog21#299

Previously, array compound literals such as (int[]){100, 200, 300} failed with an "Unexpected token" error. Struct compound literals worked correctly, but array syntax [] was unhandled in the parser. This change adds proper array compound literal handling, including scalar and pointer contexts. In scalar context, the literal returns its first element (e.g. int x = (int[]){100,200}; yields 100). In pointer context, it allocates and initializes backing storage and returns the address (e.g. int *p = (int[]){100,200};). Arithmetic expressions using literals (e.g. 50 + (int[]){100}) also evaluate correctly. Additional fixes include: - Consume missing '{' token for int/char compound literals - Add return statements to prevent control flow fall-through - Prevent segfaults in pointer assignments by allocating memory As a result, shecc now supports array compound literals alongside existing struct compound literals, improving C99 compatibility and preserving self-hosting capability. Known limitations remain: designated initializers and complex expression combinations are still unsupported.

jserv

Check https://github.com/sysprog21/shecc/blob/master/CONTRIBUTING.md carefully and indent C source files with clang-format version 18.

jserv requested changes Sep 28, 2025

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visitorckw reviewed Sep 28, 2025

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