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| author | Jason Merrill <jason@redhat.com> | 2017-05-23 21:46:16 -0400 |
|---|---|---|
| committer | Jason Merrill <jason@gcc.gnu.org> | 2017-05-23 21:46:16 -0400 |
| commit | 5726acd7d7f84a27e17719f185e3e4c5e67aeb2d (patch) | |
| tree | b840b09fa0605e400acc0557650e104335dfb670 /gcc | |
| parent | c15394ee0dd5f7bcc4ee8d1ce91d2ce98d04f2d9 (diff) | |
| download | gcc-5726acd7d7f84a27e17719f185e3e4c5e67aeb2d.zip gcc-5726acd7d7f84a27e17719f185e3e4c5e67aeb2d.tar.gz gcc-5726acd7d7f84a27e17719f185e3e4c5e67aeb2d.tar.bz2 | |
-Wunused and C++17 structured bindings
* decl.c (poplevel): Don't warn about unused structured bindings,
only real variables.
* error.c (dump_simple_decl): Handle structured bindings.
* expr.c (mark_exp_read): Look through DECL_VALUE_EXPR.
From-SVN: r248399
Diffstat (limited to 'gcc')
| -rw-r--r-- | gcc/cp/ChangeLog | 8 | ||||
| -rw-r--r-- | gcc/cp/decl.c | 5 | ||||
| -rw-r--r-- | gcc/cp/error.c | 2 | ||||
| -rw-r--r-- | gcc/cp/expr.c | 3 | ||||
| -rw-r--r-- | gcc/testsuite/g++.dg/cpp1z/decomp29.C | 26 |
5 files changed, 43 insertions, 1 deletions
diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog index 4a72b65..785dfc5 100644 --- a/gcc/cp/ChangeLog +++ b/gcc/cp/ChangeLog @@ -1,3 +1,11 @@ +2017-05-23 Jason Merrill <jason@redhat.com> + + -Wunused and C++17 structured bindings + * decl.c (poplevel): Don't warn about unused structured bindings, + only real variables. + * error.c (dump_simple_decl): Handle structured bindings. + * expr.c (mark_exp_read): Look through DECL_VALUE_EXPR. + 2017-05-23 Nathan Sidwell <nathan@acm.org> * cp-tree.h (PUSH_GLOBAL, PUSH_LOCAL, PUSH_USING): Delete. diff --git a/gcc/cp/decl.c b/gcc/cp/decl.c index 5877f37..afd47bb 100644 --- a/gcc/cp/decl.c +++ b/gcc/cp/decl.c @@ -656,7 +656,10 @@ poplevel (int keep, int reverse, int functionbody) if (VAR_P (decl) && (! TREE_USED (decl) || !DECL_READ_P (decl)) && ! DECL_IN_SYSTEM_HEADER (decl) - && DECL_NAME (decl) && ! DECL_ARTIFICIAL (decl) + /* For structured bindings, consider only real variables, not + subobjects. */ + && (DECL_DECOMPOSITION_P (decl) ? !DECL_VALUE_EXPR (decl) + : (DECL_NAME (decl) && !DECL_ARTIFICIAL (decl))) && type != error_mark_node && (!CLASS_TYPE_P (type) || !TYPE_HAS_NONTRIVIAL_DESTRUCTOR (type) diff --git a/gcc/cp/error.c b/gcc/cp/error.c index 1ae25bb..624a0e9 100644 --- a/gcc/cp/error.c +++ b/gcc/cp/error.c @@ -992,6 +992,8 @@ dump_simple_decl (cxx_pretty_printer *pp, tree t, tree type, int flags) else dump_decl (pp, DECL_NAME (t), flags); } + else if (DECL_DECOMPOSITION_P (t)) + pp_string (pp, M_("<structured bindings>")); else pp_string (pp, M_("<anonymous>")); if (flags & TFF_DECL_SPECIFIERS) diff --git a/gcc/cp/expr.c b/gcc/cp/expr.c index 77af54e..75e99e5 100644 --- a/gcc/cp/expr.c +++ b/gcc/cp/expr.c @@ -133,6 +133,9 @@ mark_exp_read (tree exp) switch (TREE_CODE (exp)) { case VAR_DECL: + if (DECL_VALUE_EXPR (exp)) + mark_exp_read (DECL_VALUE_EXPR (exp)); + gcc_fallthrough (); case PARM_DECL: DECL_READ_P (exp) = 1; break; diff --git a/gcc/testsuite/g++.dg/cpp1z/decomp29.C b/gcc/testsuite/g++.dg/cpp1z/decomp29.C new file mode 100644 index 0000000..daf07a0 --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp1z/decomp29.C @@ -0,0 +1,26 @@ +// { dg-options "-std=c++17 -Wunused" } + +#include <tuple> + +struct A { int i,j,k; }; + +A f(); + +int z; + +int main() +{ + { + auto [i,j,k] = f(); // { dg-warning "unused" } + } + { + auto [i,j,k] = f(); + z = i; + } + { + auto [i,j] = std::tuple{1,2}; // { dg-warning "unused" } + } + // No parallel second test, because in this case i and j are variables rather + // than mere bindings, so there isn't a link between them and using i will + // not prevent a warning about unused j. +} |