diff options
| -rw-r--r-- | gcc/cp/ChangeLog | 6 | ||||
| -rw-r--r-- | gcc/cp/constexpr.c | 8 | ||||
| -rw-r--r-- | gcc/testsuite/g++.dg/cpp0x/lambda/lambda-constexpr2.C | 13 |
3 files changed, 26 insertions, 1 deletions
diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog index 17e24d2..71ca21f 100644 --- a/gcc/cp/ChangeLog +++ b/gcc/cp/ChangeLog @@ -1,3 +1,9 @@ +2020-05-05 Jason Merrill <jason@redhat.com> + + PR c++/90212 + * constexpr.c (potential_constant_expression_1): In a lambda + function, consider a captured variable directly. + 2020-05-05 Iain Sandoe <iain@sandoe.co.uk> * coroutines.cc (transform_await_wrapper): Check that we have diff --git a/gcc/cp/constexpr.c b/gcc/cp/constexpr.c index 637cb74..706d8a1 100644 --- a/gcc/cp/constexpr.c +++ b/gcc/cp/constexpr.c @@ -7520,12 +7520,18 @@ potential_constant_expression_1 (tree t, bool want_rval, bool strict, bool now, variable with automatic storage duration defined outside that lambda-expression, where the reference would be an odr-use. */ + + if (want_rval) + /* Since we're doing an lvalue-rvalue conversion, this might + not be an odr-use, so evaluate the variable directly. */ + return RECUR (DECL_CAPTURED_VARIABLE (t), rval); + if (flags & tf_error) { tree cap = DECL_CAPTURED_VARIABLE (t); error ("lambda capture of %qE is not a constant expression", cap); - if (!want_rval && decl_constant_var_p (cap)) + if (decl_constant_var_p (cap)) inform (input_location, "because it is used as a glvalue"); } return false; diff --git a/gcc/testsuite/g++.dg/cpp0x/lambda/lambda-constexpr2.C b/gcc/testsuite/g++.dg/cpp0x/lambda/lambda-constexpr2.C new file mode 100644 index 0000000..b1982ab --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp0x/lambda/lambda-constexpr2.C @@ -0,0 +1,13 @@ +// PR c++/90212 +// { dg-do compile { target c++11 } } + +template<typename T> struct tuple { + constexpr tuple(T&& t) : t(t) { } + int t; +}; + +void foo() { + constexpr tuple<int> v1{1}; + constexpr auto v2 = v1; + [&]{ constexpr auto v2 = v1; }; +} |