Hello,
In the example of the patch, g++ fails to warn that the variable N::i
(introduced via a using declaration) is unused.
This is because as we want to emit the warning in poplevel, when we
walk the local bindings returned by getdecls, we forget that a
VAR_DECL introduced by a using declaration is represented by a
TREE_LIST which TREE_VALUE is the VAR_DECL, and we wrongly look for a
bare VAR_DECL.
Fixed thus and tested on x86_64-unknown-linux-gnu against trunk.
gcc/cp/
* decl.c (poplevel<warn_unused*>): Do not forget that some local
bindings are represented by a TREE_LIST.
gcc/testsuite/
* g++.dg/warn/Wunused-var-18.C: New test.
---
gcc/cp/decl.c | 46 ++++++++++++++++------------
gcc/testsuite/g++.dg/warn/Wunused-var-18.C | 14 ++++++++
2 files changed, 40 insertions(+), 20 deletions(-)
create mode 100644 gcc/testsuite/g++.dg/warn/Wunused-var-18.C
diff --git a/gcc/cp/decl.c b/gcc/cp/decl.c
index 6b5b986..dc54904 100644
--- a/gcc/cp/decl.c
+++ b/gcc/cp/decl.c
@@ -617,26 +617,32 @@ poplevel (int keep, int reverse, int functionbody)
/* Before we remove the declarations first check for unused variables. */
if ((warn_unused_variable || warn_unused_but_set_variable)
&& !processing_template_decl)
- for (decl = getdecls (); decl; decl = TREE_CHAIN (decl))
- if (TREE_CODE (decl) == VAR_DECL
- && (! TREE_USED (decl) || !DECL_READ_P (decl))
- && ! DECL_IN_SYSTEM_HEADER (decl)
- && DECL_NAME (decl) && ! DECL_ARTIFICIAL (decl)
- && TREE_TYPE (decl) != error_mark_node
- && (!CLASS_TYPE_P (TREE_TYPE (decl))
- || !TYPE_HAS_NONTRIVIAL_DESTRUCTOR (TREE_TYPE (decl))))
- {
- if (! TREE_USED (decl))
- warning (OPT_Wunused_variable, "unused variable %q+D", decl);
- else if (DECL_CONTEXT (decl) == current_function_decl
- && TREE_CODE (TREE_TYPE (decl)) != REFERENCE_TYPE
- && errorcount == unused_but_set_errorcount)
- {
- warning (OPT_Wunused_but_set_variable,
- "variable %q+D set but not used", decl);
- unused_but_set_errorcount = errorcount;
- }
- }
+ for (tree d = getdecls (); d; d = TREE_CHAIN (d))
+ {
+ /* There are cases where D itself is a TREE_LIST. See in
+ push_local_binding where the list of decls returned by
+ getdecls is built. */
+ decl = TREE_CODE (d) == TREE_LIST ? TREE_VALUE (d) : d;
+ if (TREE_CODE (decl) == VAR_DECL
+ && (! TREE_USED (decl) || !DECL_READ_P (decl))
+ && ! DECL_IN_SYSTEM_HEADER (decl)
+ && DECL_NAME (decl) && ! DECL_ARTIFICIAL (decl)
+ && TREE_TYPE (decl) != error_mark_node
+ && (!CLASS_TYPE_P (TREE_TYPE (decl))
+ || !TYPE_HAS_NONTRIVIAL_DESTRUCTOR (TREE_TYPE (decl))))
+ {
+ if (! TREE_USED (decl))
+ warning (OPT_Wunused_variable, "unused variable %q+D", decl);
+ else if (DECL_CONTEXT (decl) == current_function_decl
+ && TREE_CODE (TREE_TYPE (decl)) != REFERENCE_TYPE
+ && errorcount == unused_but_set_errorcount)
+ {
+ warning (OPT_Wunused_but_set_variable,
+ "variable %q+D set but not used", decl);
+ unused_but_set_errorcount = errorcount;
+ }
+ }
+ }
/* Remove declarations for all the DECLs in this level. */
for (link = decls; link; link = TREE_CHAIN (link))
diff --git a/gcc/testsuite/g++.dg/warn/Wunused-var-18.C
b/gcc/testsuite/g++.dg/warn/Wunused-var-18.C
new file mode 100644
index 0000000..0339663
--- /dev/null
+++ b/gcc/testsuite/g++.dg/warn/Wunused-var-18.C
@@ -0,0 +1,14 @@
+// Origin: PR c++/29028
+// { dg-options "-Wunused" }
+// { dg-do compile }
+
+namespace N
+{
+ int i; // { dg-warning "unused variable" }
+}
+
+void
+f ()
+{
+ using N::i;
+}
--
Dodji
