struct compound literal initialization #302

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

src/parser.c

jserv

Rebase the latest master branch.

jserv

Always minimize the necessary changes.

src/parser.c

jserv

Minimize the necessary changes.

src/parser.c

jserv · 2025-10-05T13:37:51Z

src/parser.c

-                        !var->ptr_level && var->array_size == 0 && var->type &&
-                        var->type->base_type == TYPE_int &&
-                        expr_result->var_name[0] == '.') {
+


sorry, i will fix these ASAP

sorry, i will fix these ASAP

Courtesy is best expressed not by empty apologies, but through tangible and dependable contributions.

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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