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| author | Jason Merrill <jason@redhat.com> | 2020-01-15 09:31:11 -0500 |
|---|---|---|
| committer | Jason Merrill <jason@redhat.com> | 2020-01-15 15:02:28 -0500 |
| commit | 7192b1ec12484f5ca8b20930d8dc4d28ab4a533a (patch) | |
| tree | 5e48e9dc719ed39cfc30318de6ce5c84ecb9e716 /gcc | |
| parent | bc071d3a951a98284a3f46043afd44c03c123376 (diff) | |
| download | gcc-7192b1ec12484f5ca8b20930d8dc4d28ab4a533a.zip gcc-7192b1ec12484f5ca8b20930d8dc4d28ab4a533a.tar.gz gcc-7192b1ec12484f5ca8b20930d8dc4d28ab4a533a.tar.bz2 | |
PR c++/92871 - bad code with xvalue and GNU ?: extension.
I steered Jakub wrong on the desired behavior for temp-extend1.C in the
context of bug 92831; it doesn't make sense to try to extend the lifetime of
a temporary that we've already materialized to evaluate the test. So this
patch munges the stabilized expression so that it won't be subject to
lifetime extension.
* call.c (prevent_lifetime_extension): New.
(build_conditional_expr_1): Use it.
Diffstat (limited to 'gcc')
| -rw-r--r-- | gcc/cp/ChangeLog | 6 | ||||
| -rw-r--r-- | gcc/cp/call.c | 24 | ||||
| -rw-r--r-- | gcc/testsuite/g++.dg/ext/temp-extend1.C | 2 |
3 files changed, 30 insertions, 2 deletions
diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog index 969827e..78eb834 100644 --- a/gcc/cp/ChangeLog +++ b/gcc/cp/ChangeLog @@ -1,3 +1,9 @@ +2020-01-15 Jason Merrill <jason@redhat.com> + + PR c++/92871 - bad code with xvalue and GNU ?: extension. + * call.c (prevent_lifetime_extension): New. + (build_conditional_expr_1): Use it. + 2020-01-14 Nathan Sidwell <nathan@acm.org> PR c++/90916 diff --git a/gcc/cp/call.c b/gcc/cp/call.c index 9a22398..32ccfc9 100644 --- a/gcc/cp/call.c +++ b/gcc/cp/call.c @@ -217,6 +217,7 @@ static conversion *merge_conversion_sequences (conversion *, conversion *); static tree build_temp (tree, tree, int, diagnostic_t *, tsubst_flags_t); static conversion *build_identity_conv (tree, tree); static inline bool conv_binds_to_array_of_unknown_bound (conversion *); +static tree prevent_lifetime_extension (tree); /* Returns nonzero iff the destructor name specified in NAME matches BASETYPE. NAME can take many forms... */ @@ -5078,7 +5079,10 @@ build_conditional_expr_1 (const op_location_t &loc, /* Make sure that lvalues remain lvalues. See g++.oliva/ext1.C. */ if (glvalue_p (arg1)) - arg2 = arg1 = cp_stabilize_reference (arg1); + { + arg2 = arg1 = cp_stabilize_reference (arg1); + arg2 = arg1 = prevent_lifetime_extension (arg1); + } else arg2 = arg1 = cp_save_expr (arg1); } @@ -12168,6 +12172,24 @@ initialize_reference (tree type, tree expr, return expr; } +/* If *P is an xvalue expression, prevent temporary lifetime extension if it + gets used to initialize a reference. */ + +static tree +prevent_lifetime_extension (tree t) +{ + tree *p = &t; + while (TREE_CODE (*p) == COMPOUND_EXPR) + p = &TREE_OPERAND (*p, 1); + while (handled_component_p (*p)) + p = &TREE_OPERAND (*p, 0); + /* Change a TARGET_EXPR from prvalue to xvalue. */ + if (TREE_CODE (*p) == TARGET_EXPR) + *p = build2 (COMPOUND_EXPR, TREE_TYPE (*p), *p, + move (TARGET_EXPR_SLOT (*p))); + return t; +} + /* Subroutine of extend_ref_init_temps. Possibly extend one initializer, which is bound either to a reference or a std::initializer_list. */ diff --git a/gcc/testsuite/g++.dg/ext/temp-extend1.C b/gcc/testsuite/g++.dg/ext/temp-extend1.C index 7df9ca5..aaef115 100644 --- a/gcc/testsuite/g++.dg/ext/temp-extend1.C +++ b/gcc/testsuite/g++.dg/ext/temp-extend1.C @@ -21,7 +21,7 @@ baz (int i) { const bool&& a = id<S[3]>{false, true, false}[i].s ? : id<S[4]>{true, false, true, false}[i].s; - if (S::c != (i ? 3 : 4)) + if (S::c != (i ? 0 : 4)) __builtin_abort (); } |