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Merged
hsutter merged 1 commit into from
Apr 20, 2023
Merged

Add diagnostics for returning a temporary, closes #381 #384

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53 changes: 53 additions & 0 deletions regression-tests/pure2-forward-return-diagnostics-error.cpp2
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Original file line number Diff line number Diff line change
@@ -0,0 +1,53 @@
fun1: () -> forward _ = { return global / 1; } // error: a 'forward' return type cannot return a temporary variable
fun4: () -> forward _ = { return global << 1; } // error: a 'forward' return type cannot return a temporary variable
fun5: () -> forward _ = { return global <=> 1; } // error: a 'forward' return type cannot return a temporary variable
fun6: () -> forward _ = { return global < 1; } // error: a 'forward' return type cannot return a temporary variable
fun7: () -> forward _ = { return global <= 1; } // error: a 'forward' return type cannot return a temporary variable
fun9: () -> forward _ = { return global >> 1; } // error: a 'forward' return type cannot return a temporary variable
fun10: () -> forward _ = { return global >= 1; } // error: a 'forward' return type cannot return a temporary variable
fun11: () -> forward _ = { return global > 1; } // error: a 'forward' return type cannot return a temporary variable
fun14: () -> forward _ = { return global + 1; } // error: a 'forward' return type cannot return a temporary variable
fun15: () -> forward _ = { return global - 1; } // error: a 'forward' return type cannot return a temporary variable
fun20: () -> forward _ = { return global || 1; } // error: a 'forward' return type cannot return a temporary variable
fun22: () -> forward _ = { return global | 1; } // error: a 'forward' return type cannot return a temporary variable
fun24: () -> forward _ = { return global && 1; } // error: a 'forward' return type cannot return a temporary variable
fun26: () -> forward _ = { return global * 1; } // error: a 'forward' return type cannot return a temporary variable
fun28: () -> forward _ = { return global % 1; } // error: a 'forward' return type cannot return a temporary variable
fun30: () -> forward _ = { return global & 1; } // error: a 'forward' return type cannot return a temporary variable
fun32: () -> forward _ = { return global ^ 1; } // error: a 'forward' return type cannot return a temporary variable
fun35: () -> forward _ = { return global == 1; } // error: a 'forward' return type cannot return a temporary variable
fun37: () -> forward _ = { return global != 1; } // error: a 'forward' return type cannot return a temporary variable
fun38: () -> forward _ = { return !ptr_g; } // error: a 'forward' return type cannot return a temporary variable
fun42: () -> forward _ = { return global&; } // error: a 'forward' return type cannot return a temporary variable
fun43: () -> forward _ = { return ptr_g~; } // error: a 'forward' return type cannot return a temporary variable

fun2: () -> forward _ = { return global /= 1; }
fun3: () -> forward _ = { return global <<= 1; }
fun8: () -> forward _ = { return global >>= 1; }
fun12: () -> forward _ = { return global++; }
fun13: () -> forward _ = { return global += 1; }
fun16: () -> forward _ = { return global -= 1; }
fun17: () -> forward _ = { return ptr_g*.x; }
fun18: () -> forward _ = { return global--; }
fun21: () -> forward _ = { return global |= 1; }
fun25: () -> forward _ = { return global *= 1; }
fun27: () -> forward _ = { return global %= 1; }
fun29: () -> forward _ = { return global &= 1; }
fun31: () -> forward _ = { return global ^= 1; }
fun36: () -> forward _ = { return global = 1; }
fun39: () -> forward _ = { return g.x; }
fun41: () -> forward _ = { return ptr_g*; }

// fun19: () -> forward _ = { return global ||= 1; } // not supported
// fun23: () -> forward _ = { return global &&= 1; } // not supported
// fun33: () -> forward _ = { return global ~= 1; } // not supported
// fun34: () -> forward _ = { return global ~ 1; } // not supported
// fun40: () -> forward _ = { return ptr_g ? ptr_g* : g; } // not supported

global: i32 = 42;
t: type = {
public x : int = 42;
}

g: t = ();
ptr_g: *t = g&;
24 changes: 24 additions & 0 deletions regression-tests/test-results/pure2-forward-return-diagnostics-error.cpp2.output
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Original file line number Diff line number Diff line change
@@ -0,0 +1,24 @@
pure2-forward-return-diagnostics-error.cpp2...
pure2-forward-return-diagnostics-error.cpp2(1,28): error: a 'forward' return type cannot return a temporary variable
pure2-forward-return-diagnostics-error.cpp2(2,28): error: a 'forward' return type cannot return a temporary variable
pure2-forward-return-diagnostics-error.cpp2(3,28): error: a 'forward' return type cannot return a temporary variable
pure2-forward-return-diagnostics-error.cpp2(4,28): error: a 'forward' return type cannot return a temporary variable
pure2-forward-return-diagnostics-error.cpp2(5,28): error: a 'forward' return type cannot return a temporary variable
pure2-forward-return-diagnostics-error.cpp2(6,28): error: a 'forward' return type cannot return a temporary variable
pure2-forward-return-diagnostics-error.cpp2(7,28): error: a 'forward' return type cannot return a temporary variable
pure2-forward-return-diagnostics-error.cpp2(8,28): error: a 'forward' return type cannot return a temporary variable
pure2-forward-return-diagnostics-error.cpp2(9,28): error: a 'forward' return type cannot return a temporary variable
pure2-forward-return-diagnostics-error.cpp2(10,28): error: a 'forward' return type cannot return a temporary variable
pure2-forward-return-diagnostics-error.cpp2(11,28): error: a 'forward' return type cannot return a temporary variable
pure2-forward-return-diagnostics-error.cpp2(12,28): error: a 'forward' return type cannot return a temporary variable
pure2-forward-return-diagnostics-error.cpp2(13,28): error: a 'forward' return type cannot return a temporary variable
pure2-forward-return-diagnostics-error.cpp2(14,28): error: a 'forward' return type cannot return a temporary variable
pure2-forward-return-diagnostics-error.cpp2(15,28): error: a 'forward' return type cannot return a temporary variable
pure2-forward-return-diagnostics-error.cpp2(16,28): error: a 'forward' return type cannot return a temporary variable
pure2-forward-return-diagnostics-error.cpp2(17,28): error: a 'forward' return type cannot return a temporary variable
pure2-forward-return-diagnostics-error.cpp2(18,28): error: a 'forward' return type cannot return a temporary variable
pure2-forward-return-diagnostics-error.cpp2(19,28): error: a 'forward' return type cannot return a temporary variable
pure2-forward-return-diagnostics-error.cpp2(20,28): error: a 'forward' return type cannot return a temporary variable
pure2-forward-return-diagnostics-error.cpp2(21,28): error: a 'forward' return type cannot return a temporary variable
pure2-forward-return-diagnostics-error.cpp2(22,28): error: a 'forward' return type cannot return a temporary variable

9 changes: 9 additions & 0 deletions source/cppfront.cpp
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Expand Up @@ -2206,6 +2206,15 @@ class cppfront
"a 'forward' return type cannot return a local variable"
);
return;
} else if (
is_literal(tok->type()) || n.expression->expr->is_result_a_temporary_variable()
)
{
errors.emplace_back(
n.position(),
"a 'forward' return type cannot return a temporary variable"
);
return;
}
}

Expand Down
42 changes: 42 additions & 0 deletions source/parse.h
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Original file line number Diff line number Diff line change
Expand Up @@ -195,6 +195,8 @@ struct prefix_expression_node
return expr.get();
}

auto is_result_a_temporary_variable() const -> bool;

auto position() const -> source_position;
auto visit(auto& v, int depth) -> void;
};
Expand Down Expand Up @@ -257,6 +259,20 @@ struct binary_expression_node
return { nullptr, nullptr };
}

auto is_result_a_temporary_variable() const -> bool {
if constexpr (std::string_view(Name.value) == "assignment") {
assert(expr);
return expr->is_result_a_temporary_variable();
} else {
if (terms.empty()) {
assert(expr);
return expr->is_result_a_temporary_variable();
} else {
return true;
}
}
}

auto position() const
-> source_position
{
Expand Down Expand Up @@ -470,6 +486,15 @@ struct postfix_expression_node
auto get_first_token_ignoring_this() const
-> token const*;

auto is_result_a_temporary_variable() const -> bool {
if (ops.empty()) {
return false;
} else {
return (ops.front().op->type() == lexeme::Ampersand
|| ops.front().op->type() == lexeme::Tilde);
}
}

// Internals
//
auto position() const -> source_position
Expand All @@ -481,6 +506,14 @@ struct postfix_expression_node
auto visit(auto& v, int depth) -> void;
};

auto prefix_expression_node::is_result_a_temporary_variable() const -> bool {
if (ops.empty()) {
return expr->is_result_a_temporary_variable();
} else {
return true;
}
}


auto expression_node::get_lhs_rhs_if_simple_assignment() const
-> assignment_expression_lhs_rhs
Expand Down Expand Up @@ -807,6 +840,15 @@ struct is_as_expression_node
return expr->get_postfix_expression_node();
}

auto is_result_a_temporary_variable() const -> bool {
if (ops.empty()) {
assert(expr);
return expr->is_result_a_temporary_variable();
} else {
return true;
}
}

auto position() const
-> source_position
{
Expand Down