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Merge pull request #5719 from jwaxy/patch-1

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Prevent returning a struct containing compound literal slice
This commit is contained in:
gingerBill
2025-09-27 14:11:57 +01:00
committed by GitHub
parent a7af6055b0 15fe0bfe59
commit 27d9ab5dd8
1 changed files with 66 additions and 55 deletions
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src/check_stmt.cpp
+66 -55
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@@ -2541,6 +2541,71 @@ gb_internal void check_if_stmt(CheckerContext *ctx, Ast *node, u32 mod_flags) {
check_close_scope(ctx);
}
// NOTE(bill): This is very basic escape analysis
// This needs to be improved tremendously, and a lot of it done during the
// middle-end (or LLVM side) to improve checks and error messages
void check_unsafe_return(Operand const &o, Type *type, Ast *expr) {
auto unsafe_return_error = [](Operand const &o, char const *msg, Type *extra_type=nullptr) {
gbString s = expr_to_string(o.expr);
if (extra_type) {
gbString t = type_to_string(extra_type);
error(o.expr, "It is unsafe to return %s ('%s') of type ('%s') from a procedure, as it uses the current stack frame's memory", msg, s, t);
gb_string_free(t);
} else {
error(o.expr, "It is unsafe to return %s ('%s') from a procedure, as it uses the current stack frame's memory", msg, s);
}
gb_string_free(s);
};
if (expr->kind == Ast_CompoundLit && is_type_slice(type)) {
ast_node(cl, CompoundLit, expr);
if (cl->elems.count == 0) {
return;
}
unsafe_return_error(o, "a compound literal of a slice");
} else if (expr->kind == Ast_UnaryExpr && expr->UnaryExpr.op.kind == Token_And) {
Ast *x = unparen_expr(expr->UnaryExpr.expr);
Entity *e = entity_of_node(x);
if (is_entity_local_variable(e)) {
unsafe_return_error(o, "the address of a local variable");
} else if (x->kind == Ast_CompoundLit) {
unsafe_return_error(o, "the address of a compound literal");
} else if (x->kind == Ast_IndexExpr) {
Entity *f = entity_of_node(x->IndexExpr.expr);
if (f && (is_type_array_like(f->type) || is_type_matrix(f->type))) {
if (is_entity_local_variable(f)) {
unsafe_return_error(o, "the address of an indexed variable", f->type);
}
}
} else if (x->kind == Ast_MatrixIndexExpr) {
Entity *f = entity_of_node(x->MatrixIndexExpr.expr);
if (f && (is_type_matrix(f->type) && is_entity_local_variable(f))) {
unsafe_return_error(o, "the address of an indexed variable", f->type);
}
}
} else if (expr->kind == Ast_SliceExpr) {
Ast *x = unparen_expr(expr->SliceExpr.expr);
Entity *e = entity_of_node(x);
if (is_entity_local_variable(e) && is_type_array(e->type)) {
unsafe_return_error(o, "a slice of a local variable");
} else if (x->kind == Ast_CompoundLit) {
unsafe_return_error(o, "a slice of a compound literal");
}
} else if (o.mode == Addressing_Constant && is_type_slice(type)) {
ERROR_BLOCK();
unsafe_return_error(o, "a compound literal of a slice");
error_line("\tNote: A constant slice value will use the memory of the current stack frame\n");
} else if (expr->kind == Ast_CompoundLit) {
ast_node(cl, CompoundLit, expr);
for (Ast *elem : cl->elems) {
if (elem->kind == Ast_FieldValue) {
ast_node(fv, FieldValue, elem);
check_unsafe_return(o, entity_of_node(fv->field)->type, fv->value);
}
}
}
}
gb_internal void check_return_stmt(CheckerContext *ctx, Ast *node) {
ast_node(rs, ReturnStmt, node);
@@ -2617,61 +2682,7 @@ gb_internal void check_return_stmt(CheckerContext *ctx, Ast *node) {
expr = unparen_expr(arg);
}
auto unsafe_return_error = [](Operand const &o, char const *msg, Type *extra_type=nullptr) {
gbString s = expr_to_string(o.expr);
if (extra_type) {
gbString t = type_to_string(extra_type);
error(o.expr, "It is unsafe to return %s ('%s') of type ('%s') from a procedure, as it uses the current stack frame's memory", msg, s, t);
gb_string_free(t);
} else {
error(o.expr, "It is unsafe to return %s ('%s') from a procedure, as it uses the current stack frame's memory", msg, s);
}
gb_string_free(s);
};
// NOTE(bill): This is very basic escape analysis
// This needs to be improved tremendously, and a lot of it done during the
// middle-end (or LLVM side) to improve checks and error messages
if (expr->kind == Ast_CompoundLit && is_type_slice(o.type)) {
ast_node(cl, CompoundLit, expr);
if (cl->elems.count == 0) {
continue;
}
unsafe_return_error(o, "a compound literal of a slice");
} else if (expr->kind == Ast_UnaryExpr && expr->UnaryExpr.op.kind == Token_And) {
Ast *x = unparen_expr(expr->UnaryExpr.expr);
Entity *e = entity_of_node(x);
if (is_entity_local_variable(e)) {
unsafe_return_error(o, "the address of a local variable");
} else if (x->kind == Ast_CompoundLit) {
unsafe_return_error(o, "the address of a compound literal");
} else if (x->kind == Ast_IndexExpr) {
Entity *f = entity_of_node(x->IndexExpr.expr);
if (f && (is_type_array_like(f->type) || is_type_matrix(f->type))) {
if (is_entity_local_variable(f)) {
unsafe_return_error(o, "the address of an indexed variable", f->type);
}
}
} else if (x->kind == Ast_MatrixIndexExpr) {
Entity *f = entity_of_node(x->MatrixIndexExpr.expr);
if (f && (is_type_matrix(f->type) && is_entity_local_variable(f))) {
unsafe_return_error(o, "the address of an indexed variable", f->type);
}
}
} else if (expr->kind == Ast_SliceExpr) {
Ast *x = unparen_expr(expr->SliceExpr.expr);
Entity *e = entity_of_node(x);
if (is_entity_local_variable(e) && is_type_array(e->type)) {
unsafe_return_error(o, "a slice of a local variable");
} else if (x->kind == Ast_CompoundLit) {
unsafe_return_error(o, "a slice of a compound literal");
}
} else if (o.mode == Addressing_Constant && is_type_slice(o.type)) {
ERROR_BLOCK();
unsafe_return_error(o, "a compound literal of a slice");
error_line("\tNote: A constant slice value will use the memory of the current stack frame\n");
}
check_unsafe_return(o, o.type, expr);
}
}