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| author | Marek Polacek <polacek@redhat.com> | 2019-08-28 02:22:29 +0000 |
|---|---|---|
| committer | Marek Polacek <mpolacek@gcc.gnu.org> | 2019-08-28 02:22:29 +0000 |
| commit | 8692693732e89806058d3b9c91132fb83661b214 (patch) | |
| tree | 4d6fb359b2dfa84fd95432293af3448db1c32dd2 /gcc/cp/semantics.c | |
| parent | 14da3939da3adcef84816573caa9d93c7367507e (diff) | |
| download | gcc-8692693732e89806058d3b9c91132fb83661b214.zip gcc-8692693732e89806058d3b9c91132fb83661b214.tar.gz gcc-8692693732e89806058d3b9c91132fb83661b214.tar.bz2 | |
PR c++/81676 - bogus -Wunused warnings in constexpr if.
* semantics.c (maybe_mark_exp_read_r): New function.
(finish_if_stmt): Call it on THEN_CLAUSE and ELSE_CLAUSE.
* g++.dg/cpp1z/constexpr-if31.C: New test.
* g++.dg/cpp1z/constexpr-if32.C: New test.
From-SVN: r274982
Diffstat (limited to 'gcc/cp/semantics.c')
| -rw-r--r-- | gcc/cp/semantics.c | 22 |
1 files changed, 22 insertions, 0 deletions
diff --git a/gcc/cp/semantics.c b/gcc/cp/semantics.c index 8603e57..b61d86f 100644 --- a/gcc/cp/semantics.c +++ b/gcc/cp/semantics.c @@ -810,6 +810,18 @@ finish_else_clause (tree if_stmt) ELSE_CLAUSE (if_stmt) = pop_stmt_list (ELSE_CLAUSE (if_stmt)); } +/* Callback for cp_walk_tree to mark all {VAR,PARM}_DECLs in a tree as + read. */ + +static tree +maybe_mark_exp_read_r (tree *tp, int *, void *) +{ + tree t = *tp; + if (VAR_P (t) || TREE_CODE (t) == PARM_DECL) + mark_exp_read (t); + return NULL_TREE; +} + /* Finish an if-statement. */ void @@ -817,6 +829,16 @@ finish_if_stmt (tree if_stmt) { tree scope = IF_SCOPE (if_stmt); IF_SCOPE (if_stmt) = NULL; + if (IF_STMT_CONSTEXPR_P (if_stmt)) + { + /* Prevent various -Wunused warnings. We might not instantiate + either of these branches, so we would not mark the variables + used in that branch as read. */ + cp_walk_tree_without_duplicates (&THEN_CLAUSE (if_stmt), + maybe_mark_exp_read_r, NULL); + cp_walk_tree_without_duplicates (&ELSE_CLAUSE (if_stmt), + maybe_mark_exp_read_r, NULL); + } add_stmt (do_poplevel (scope)); } |