https://gcc.gnu.org/g:5ca5e1d54f237770ef5f32ff20c69711f720551c
commit r16-2077-g5ca5e1d54f237770ef5f32ff20c69711f720551c
Author: Jonathan Wakely <jwak...@redhat.com>
Date: Tue Jul 1 12:44:04 2025 +0100
libstdc++: Make VERIFY a variadic macro
This defines the testsuite assertion macro VERIFY so that it allows
un-parenthesized expressions containing commas. This matches how assert
is defined in C++26, following the approval of P2264R7.
The primary motivation is to allow expressions that the preprocessor
splits into multiple arguments, e.g.
VERIFY( vec == std::vector<int>{1,2,3,4} );
To achieve this, VERIFY is redefined as a variadic macro and then the
arguments are grouped together again through the use of __VA_ARGS__.
The implementation is complex due to the following points:
- The arguments __VA_ARGS__ are contextually-converted to bool, so that
scoped enums and types that are not contextually convertible to bool
cannot be used with VERIFY.
- bool(__VA_ARGS__) is used so that multiple arguments (i.e. those which
are separated by top-level commas) are ill-formed. Nested commas are
allowed, but likely mistakes such as VERIFY( cond, "some string" ) are
ill-formed.
- The bool(__VA_ARGS__) expression needs to be unevaluated, so that we
don't evaluate __VA_ARGS__ more than once. The simplest way to do that
would be just sizeof bool(__VA_ARGS__), without parentheses to avoid a
vexing parse for VERIFY(bool(i)). However that wouldn't work for e.g.
VERIFY( []{ return true; }() ), because lambda expressions are not
allowed in unevaluated contexts until C++20. So we use another
conditional expression with bool(__VA_ARGS__) as the unevaluated
operand.
libstdc++-v3/ChangeLog:
* testsuite/util/testsuite_hooks.h (VERIFY): Define as variadic
macro.
* testsuite/ext/verify_neg.cc: New test.
Reviewed-by: Tomasz Kamiński <tkami...@redhat.com>
Diff:
---
libstdc++-v3/testsuite/ext/verify_neg.cc | 28 +++++++++++++++++++++++++++
libstdc++-v3/testsuite/util/testsuite_hooks.h | 17 +++++++---------
2 files changed, 35 insertions(+), 10 deletions(-)
diff --git a/libstdc++-v3/testsuite/ext/verify_neg.cc
b/libstdc++-v3/testsuite/ext/verify_neg.cc
new file mode 100644
index 000000000000..ce033741beeb
--- /dev/null
+++ b/libstdc++-v3/testsuite/ext/verify_neg.cc
@@ -0,0 +1,28 @@
+// { dg-do compile { target c++11 } }
+
+#include <testsuite_hooks.h>
+
+struct X { explicit operator void*() const { return nullptr; } };
+
+void
+test_VERIFY(int i)
+{
+ // This should not be parsed as a function type bool(bool(i)):
+ VERIFY( bool(i) );
+
+ // This should not produce warnings about lambda in unevaluated context:
+ VERIFY( []{ return 1; }() );
+
+ // Only one expression allowed:
+ VERIFY(1, 2); // { dg-error "in expansion of macro" }
+ // { dg-error "compound expression in functional cast" "" { target *-*-* } 0
}
+
+ // A scoped enum is not contextually convertible to bool:
+ enum class E { E0 };
+ VERIFY( E::E0 ); // { dg-error "could not convert" }
+
+ // explicit conversion to void* is not contextually convertible to bool:
+ X x;
+ VERIFY( x ); // { dg-error "in expansion of macro" }
+ // { dg-error "invalid cast .* to type 'bool'" "" { target *-*-* } 0 }
+}
diff --git a/libstdc++-v3/testsuite/util/testsuite_hooks.h
b/libstdc++-v3/testsuite/util/testsuite_hooks.h
index faa01ba6abd8..bf34fd121c1b 100644
--- a/libstdc++-v3/testsuite/util/testsuite_hooks.h
+++ b/libstdc++-v3/testsuite/util/testsuite_hooks.h
@@ -58,16 +58,13 @@
# define _VERIFY_PRINT(S, F, L, P, C) __builtin_printf(S, F, L, P, C)
#endif
-#define VERIFY(fn) \
- do \
- { \
- if (! (fn))
\
- {
\
- _VERIFY_PRINT("%s:%d: %s: Assertion '%s' failed.\n", \
- __FILE__, __LINE__, __PRETTY_FUNCTION__, #fn); \
- __builtin_abort(); \
- }
\
- } while (false)
+#define VERIFY(...) \
+ ((void)((__VA_ARGS__) \
+ ? (void)(true ? true : bool(__VA_ARGS__)) \
+ : (_VERIFY_PRINT("%s:%d: %s: Assertion '%s' failed.\n", \
+ __FILE__, __LINE__, __PRETTY_FUNCTION__, \
+ #__VA_ARGS__), \
+ __builtin_abort())))
#ifdef _GLIBCXX_HAVE_UNISTD_H
# include <unistd.h>
