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Fix array compound literal parsing #309

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34c8aac
Fix array compound literal parsing to preserve pointer semantics
lorettayao Oct 6, 2025
a35da48
Preserve pointer semantics for array literals
lorettayao Oct 6, 2025
b44dc57
Fix formatting, add testcase, remove static
lorettayao Oct 6, 2025
1f7bed4
Fix misleading function naming
lorettayao Oct 8, 2025
d6b9fbf
Fix data format according to warnings
lorettayao Oct 8, 2025
272c912
add: test case for array compound literals
lorettayao Oct 8, 2025
accfedf
Change function name and remove test case
lorettayao Oct 8, 2025
fefbeee
Update driver snapshots after decay tests
lorettayao Oct 8, 2025
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184 changes: 151 additions & 33 deletions src/parser.c
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Original file line number Diff line number Diff line change
Expand Up @@ -45,7 +45,10 @@ void parse_array_init(var_t *var,
block_t *parent,
basic_block_t **bb,
bool emit_code);

void parse_array_compound_literal(var_t *var,
block_t *parent,
basic_block_t **bb,
bool emit_code);

label_t *find_label(char *name)
{
Expand Down Expand Up @@ -1283,6 +1286,77 @@ void parse_array_init(var_t *var,
}
}

void parse_array_compound_literal(var_t *var,
block_t *parent,
basic_block_t **bb,
bool emit_code)
{
int elem_size = var->type->size;
int count = 0;
var->array_size = 0;
var->init_val = 0;
if (!lex_peek(T_close_curly, NULL)) {
for (;;) {
read_expr(parent, bb);
read_ternary_operation(parent, bb);
var_t *value = opstack_pop();
if (count == 0)
var->init_val = value->init_val;
if (emit_code) {
var_t target = {0};
target.type = var->type;
target.ptr_level = 0;
var_t *store_val = resize_var(parent, bb, value, &target);
var_t *elem_addr =
compute_element_address(parent, bb, var, count, elem_size);
add_insn(parent, *bb, OP_write, NULL, elem_addr, store_val,
elem_size, NULL);
}
count++;
if (!lex_accept(T_comma))
break;
if (lex_peek(T_close_curly, NULL))
break;
}
}

lex_expect(T_close_curly);
var->array_size = count;
}
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Add a new blank line.

/* Identify compiler-emitted temporaries that hold array compound literals.
* Parsing assigns these temporaries synthetic names via gen_name_to (".tN")
* and they keep array metadata without pointer indirection.
*/
bool is_compound_literal_array_temp(var_t *var)
{
return var && var->array_size > 0 && !var->ptr_level &&
var->var_name[0] == '.';
}

var_t *scalarize_array_literal(block_t *parent,
basic_block_t **bb,
var_t *array_var,
type_t *hint_type)
{
if (!is_compound_literal_array_temp(array_var))
return array_var;

type_t *elem_type = hint_type ? hint_type : array_var->type;
if (!elem_type)
elem_type = TY_int;

int elem_size = elem_type->size;
if (elem_size <= 0)
elem_size = TY_int->size;

var_t *scalar = require_typed_var(parent, elem_type);
scalar->ptr_level = 0;
gen_name_to(scalar->var_name);
scalar->init_val = array_var->init_val;

add_insn(parent, *bb, OP_read, scalar, array_var, NULL, elem_size, NULL);
return scalar;
}
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Add a line break.

void read_inner_var_decl(var_t *vd, bool anon, bool is_param)
{
/* Preserve typedef pointer level - don't reset if already inherited */
Expand Down Expand Up @@ -1575,7 +1649,16 @@ void read_func_parameters(func_t *func, block_t *parent, basic_block_t **bb)
read_ternary_operation(parent, bb);

param = opstack_pop();

if (func) {
if (param_num < func->num_params) {
var_t *target = &func->param_defs[param_num];
if (!target->ptr_level && !target->array_size)
param = scalarize_array_literal(parent, bb, param,
target->type);
} else if (func->va_args) {
param = scalarize_array_literal(parent, bb, param, TY_int);
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@cubic-dev-ai cubic-dev-ai bot Oct 6, 2025 •
edited
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Passing an array compound literal to a variadic function now yields the first element value instead of the temporary array’s address, so variadic calls like printf("%p", (int[]){1,2}); receive an integer instead of a pointer.

Prompt for AI agents 
Address the following comment on src/parser.c at line 1653:

<comment>Passing an array compound literal to a variadic function now yields the first element value instead of the temporary array’s address, so variadic calls like `printf(&quot;%p&quot;, (int[]){1,2});` receive an integer instead of a pointer.</comment>

<file context>
@@ -1575,7 +1643,16 @@ void read_func_parameters(func_t *func, block_t *parent, basic_block_t **bb)
+                    param = scalarize_array_literal(parent, bb, param,
+                                                    target-&gt;type);
+            } else if (func-&gt;va_args) {
+                param = scalarize_array_literal(parent, bb, param, TY_int);
+            }
+        }
</file context>

✅ Addressed in d6b9fbf

}
}
/* Handle parameter type conversion for direct calls.
* Indirect calls currently don't provide function instance.
*/
Expand Down Expand Up @@ -2017,9 +2100,16 @@ void read_expr_operand(block_t *parent, basic_block_t **bb)
bool is_array_literal = (cast_ptr_level == -1);
if (is_array_literal)
cast_ptr_level = 0; /* Reset for normal processing */

bool consumed_close_brace = false;
/* Check if this is a pointer compound literal */
if (cast_ptr_level > 0) {
if (is_array_literal) {
compound_var->array_size = 0;
add_insn(parent, *bb, OP_allocat, compound_var, NULL, NULL, 0,
NULL);
parse_array_compound_literal(compound_var, parent, bb, true);
opstack_push(compound_var);
consumed_close_brace = true;
} else if (cast_ptr_level > 0) {
/* Pointer compound literal: (int*){&x} */
compound_var->ptr_level = cast_ptr_level;

Expand Down Expand Up @@ -2187,7 +2277,8 @@ void read_expr_operand(block_t *parent, basic_block_t **bb)
}
}

lex_expect(T_close_curly);
if (!consumed_close_brace)
lex_expect(T_close_curly);
} else {
/* Regular parenthesized expression */
read_expr(parent, bb);
Expand Down Expand Up @@ -2810,6 +2901,16 @@ void read_expr(block_t *parent, basic_block_t **bb)
continue; /* skip normal processing */
}

bool rs1_is_ptr_like = rs1 && (rs1->ptr_level || rs1->array_size);
bool rs2_is_ptr_like = rs2 && (rs2->ptr_level || rs2->array_size);

if (is_compound_literal_array_temp(rs1) && !rs2_is_ptr_like)
rs1 = scalarize_array_literal(parent, bb, rs1,
rs2 && rs2->type ? rs2->type : NULL);

if (is_compound_literal_array_temp(rs2) && !rs1_is_ptr_like)
rs2 = scalarize_array_literal(parent, bb, rs2,
rs1 && rs1->type ? rs1->type : NULL);
/* Constant folding for binary operations */
if (rs1 && rs2 && rs1->init_val && !rs1->ptr_level && !rs1->is_global &&
rs2->init_val && !rs2->ptr_level && !rs2->is_global) {
Expand Down Expand Up @@ -3430,7 +3531,7 @@ void finalize_logical(opcode_t op,

void read_ternary_operation(block_t *parent, basic_block_t **bb)
{
var_t *vd, *rs1;
var_t *vd;

if (!lex_accept(T_question))
return;
Expand All @@ -3455,17 +3556,39 @@ void read_ternary_operation(block_t *parent, basic_block_t **bb)
abort();
}

rs1 = opstack_pop();
vd = require_var(parent);
gen_name_to(vd->var_name);
add_insn(parent, then_, OP_assign, vd, rs1, NULL, 0, NULL);
var_t *true_val = opstack_pop();

/* false branch */
read_expr(parent, &else_);
bb_connect(*bb, else_, ELSE);
var_t *false_val = opstack_pop();
bool true_array = is_compound_literal_array_temp(true_val);
bool false_array = is_compound_literal_array_temp(false_val);

if (true_array && !false_array)
true_val = scalarize_array_literal(parent, &then_, true_val,
false_val ? false_val->type : NULL);

rs1 = opstack_pop();
add_insn(parent, else_, OP_assign, vd, rs1, NULL, 0, NULL);
if (false_array && !true_array)
false_val = scalarize_array_literal(parent, &else_, false_val,
true_val ? true_val->type : NULL);

vd = require_var(parent);
gen_name_to(vd->var_name);
add_insn(parent, then_, OP_assign, vd, true_val, NULL, 0, NULL);
add_insn(parent, else_, OP_assign, vd, false_val, NULL, 0, NULL);

var_t *array_ref = NULL;
if (is_compound_literal_array_temp(true_val))
array_ref = true_val;
else if (is_compound_literal_array_temp(false_val))
array_ref = false_val;

if (array_ref) {
vd->array_size = array_ref->array_size;
vd->init_val = array_ref->init_val;
vd->type = array_ref->type;
}

vd->is_ternary_ret = true;
opstack_push(vd);
Expand Down Expand Up @@ -3614,6 +3737,11 @@ bool read_body_assignment(char *token,

read_expr(parent, bb);

var_t *rhs_val = opstack_pop();
if (!lvalue.ptr_level && !lvalue.is_reference)
rhs_val = scalarize_array_literal(parent, bb, rhs_val,
lvalue.type);
opstack_push(rhs_val);
vd = require_var(parent);
vd->init_val = increment_size;
gen_name_to(vd->var_name);
Expand Down Expand Up @@ -4356,27 +4484,12 @@ basic_block_t *read_body_statement(block_t *parent, basic_block_t *bb)

var_t *expr_result = opstack_pop();

/* Handle array compound literal to scalar assignment.
* When assigning array compound literals to scalar
* variables, use the first element value rather than array
* address.
*/
if (expr_result && expr_result->array_size > 0 &&
!var->ptr_level && var->array_size == 0 && var->type &&
(var->type->base_type == TYPE_int ||
var->type->base_type == TYPE_short) &&
expr_result->var_name[0] == '.') {
var_t *first_elem = require_var(parent);
first_elem->type = var->type;
gen_name_to(first_elem->var_name);

/* Extract first element from compound literal array */
add_insn(parent, bb, OP_read, first_elem, expr_result,
NULL, var->type->size, NULL);
expr_result = first_elem;
}
var_t *rhs = expr_result;
if (!var->ptr_level && var->array_size == 0)
rhs = scalarize_array_literal(parent, &bb, rhs,
var->type);

rs1 = resize_var(parent, &bb, expr_result, var);
rs1 = resize_var(parent, &bb, rhs, var);
add_insn(parent, bb, OP_assign, var, rs1, NULL, 0, NULL);
}
}
Expand Down Expand Up @@ -4468,8 +4581,13 @@ basic_block_t *read_body_statement(block_t *parent, basic_block_t *bb)
} else {
read_expr(parent, &bb);
read_ternary_operation(parent, &bb);
var_t *expr_result = opstack_pop();
var_t *rhs = expr_result;
if (!nv->ptr_level && nv->array_size == 0)
rhs = scalarize_array_literal(parent, &bb, rhs,
nv->type);

rs1 = resize_var(parent, &bb, opstack_pop(), nv);
rs1 = resize_var(parent, &bb, rhs, nv);
add_insn(parent, bb, OP_assign, nv, rs1, NULL, 0, NULL);
}
}
Expand Down
39 changes: 39 additions & 0 deletions tests/array_ptr.c
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Original file line number Diff line number Diff line change
@@ -0,0 +1,39 @@
#include <stdio.h>

int add(int a, int b)
{
return a + b;
}

int main(void)
{
int *a = (int[]){1, 2, 3, 4, 5};

printf("Testing basic array compound literal:\n");
for (int i = 0; i < 5; i++)
printf(" a[%d] = %d\n", i, a[i]);

int sum = a[0] + a[4];
printf("Sum = %d (expect 6)\n", sum);

int base = 50;
int combined = base + (int[]){100, 200};
printf("base + (int[]){100,200} = %d (expect 150)\n", combined);

int acc = 25;
acc += (int[]){100, 200};
printf("acc after += array literal = %d (expect 125)\n", acc);

int flag = 1;
int ternary_val = flag ? (int[]){25, 50} : (int){15};
printf("ternary true branch = %d (expect 25)\n", ternary_val);

flag = 0;
ternary_val = flag ? (int[]){25, 50} : (int){15};
printf("ternary false branch = %d (expect 15)\n", ternary_val);

int func_val = add((int){5}, (int[]){10, 20, 30});
printf("add((int){5}, (int[]){10,20,30}) = %d (expect 15)\n", func_val);

return 0;
}
22 changes: 22 additions & 0 deletions tests/driver.sh
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Expand Up @@ -724,6 +724,28 @@ int main() {
}
EOF

# Test: Array compound literal decay to pointer in initializer
try_ 0 << EOF
int main(void) {
int *arr = (int[]){1, 2, 3, 4, 5};
return arr[0] != 1 || arr[4] != 5;
}
EOF

# Test: Passing array compound literal as pointer argument
try_ 0 << EOF
int sum(int *p, int n) {
int s = 0;
for (int i = 0; i < n; i++)
s += p[i];
return s;
}
int main(void) {
int s = sum((int[]){1, 2, 3, 0, 0}, 3);
return s != 6;
}
EOF

# Test: Complex expression with compound literals
try_ 77 << EOF
int main() {
Expand Down
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