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- /* Compile-time valid expression checker for GDB, the GNU debugger.
- Copyright (C) 2017-2022 Free Software Foundation, Inc.
- This file is part of GDB.
- This program is free software; you can redistribute it and/or modify
- it under the terms of the GNU General Public License as published by
- the Free Software Foundation; either version 3 of the License, or
- (at your option) any later version.
- This program is distributed in the hope that it will be useful,
- but WITHOUT ANY WARRANTY; without even the implied warranty of
- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- GNU General Public License for more details.
- You should have received a copy of the GNU General Public License
- along with this program. If not, see <http://www.gnu.org/licenses/>. */
- /* Helper macros used to build compile-time unit tests that make sure
- that invalid expressions that should not compile would not compile,
- and that expressions that should compile do compile, and have the
- right type. This is mainly used to verify that some utility's API
- is really as safe as intended. */
- #ifndef COMMON_VALID_EXPR_H
- #define COMMON_VALID_EXPR_H
- #include "gdbsupport/preprocessor.h"
- #include "gdbsupport/traits.h"
- /* Macro that uses SFINAE magic to detect whether the EXPR expression
- is either valid or ill-formed, at compile time, without actually
- producing compile-time errors. I.e., check that bad uses of the
- types (e.g., involving mismatching types) would be caught at
- compile time. If the expression is valid, also check whether the
- expression has the right type.
- EXPR must be defined in terms of some of the template parameters,
- so that template substitution failure discards the overload instead
- of causing a real compile error. TYPES is thus the list of types
- involved in the expression, and TYPENAMES is the same list, but
- with each element prefixed by "typename". These are passed as
- template parameter types to the templates within the macro.
- VALID is a boolean that indicates whether the expression is
- supposed to be valid or invalid.
- EXPR_TYPE is the expected type of EXPR. Only meaningful iff VALID
- is true. If VALID is false, then you must pass "void" as expected
- type.
- Each invocation of the macro is wrapped in its own namespace to
- avoid ODR violations. The generated namespace only includes the
- line number, so client code should wrap sets of calls in a
- test-specific namespace too, to fully guarantee uniqueness between
- the multiple clients in the codebase. */
- #define CHECK_VALID_EXPR_INT(TYPENAMES, TYPES, VALID, EXPR_TYPE, EXPR) \
- namespace CONCAT (check_valid_expr, __LINE__) { \
- \
- template <TYPENAMES, typename = decltype (EXPR)> \
- struct archetype \
- { \
- }; \
- \
- static_assert (gdb::is_detected_exact<archetype<TYPES, EXPR_TYPE>, \
- archetype, TYPES>::value == VALID, \
- ""); \
- } /* namespace */
- /* A few convenience macros that support expressions involving a
- varying numbers of types. If you need more types, feel free to add
- another variant. */
- #define CHECK_VALID_EXPR_1(T1, VALID, EXPR_TYPE, EXPR) \
- CHECK_VALID_EXPR_INT (ESC_PARENS (typename T1), \
- ESC_PARENS (T1), \
- VALID, EXPR_TYPE, EXPR)
- #define CHECK_VALID_EXPR_2(T1, T2, VALID, EXPR_TYPE, EXPR) \
- CHECK_VALID_EXPR_INT (ESC_PARENS(typename T1, typename T2), \
- ESC_PARENS (T1, T2), \
- VALID, EXPR_TYPE, EXPR)
- #define CHECK_VALID_EXPR_3(T1, T2, T3, VALID, EXPR_TYPE, EXPR) \
- CHECK_VALID_EXPR_INT (ESC_PARENS (typename T1, typename T2, typename T3), \
- ESC_PARENS (T1, T2, T3), \
- VALID, EXPR_TYPE, EXPR)
- #define CHECK_VALID_EXPR_4(T1, T2, T3, T4, VALID, EXPR_TYPE, EXPR) \
- CHECK_VALID_EXPR_INT (ESC_PARENS (typename T1, typename T2, \
- typename T3, typename T4), \
- ESC_PARENS (T1, T2, T3, T4), \
- VALID, EXPR_TYPE, EXPR)
- #define CHECK_VALID_EXPR_5(T1, T2, T3, T4, T5, VALID, EXPR_TYPE, EXPR) \
- CHECK_VALID_EXPR_INT (ESC_PARENS (typename T1, typename T2, \
- typename T3, typename T4, \
- typename T5), \
- ESC_PARENS (T1, T2, T3, T4, T5), \
- VALID, EXPR_TYPE, EXPR)
- #define CHECK_VALID_EXPR_6(T1, T2, T3, T4, T5, T6, \
- VALID, EXPR_TYPE, EXPR) \
- CHECK_VALID_EXPR_INT (ESC_PARENS (typename T1, typename T2, \
- typename T3, typename T4, \
- typename T5, typename T6), \
- ESC_PARENS (T1, T2, T3, T4, T5, T6), \
- VALID, EXPR_TYPE, EXPR)
- #endif /* COMMON_VALID_EXPR_H */
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