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C++ PATCH for c++/55357 (-Wshadow and lambdas)
- From: Jason Merrill <jason at redhat dot com>
- To: gcc-patches List <gcc-patches at gcc dot gnu dot org>
- Date: Sat, 16 Mar 2013 21:38:26 -0400
- Subject: C++ PATCH for c++/55357 (-Wshadow and lambdas)
The submitter of this PR suggested that we don't want to warn about
shadowing of a local variable by a lambda parameter; I think we do,
since local variables can be used in lambdas, but we don't want a
duplicate warning when we copy the parameter into the conversion thunk.
Tested x86_64-pc-linux-gnu, applying to trunk.
commit cd911b455722c1b88d21ac7dcb192aae53ef7f16
Author: Jason Merrill <jason@redhat.com>
Date: Tue Mar 5 14:25:04 2013 -0500
PR c++/55357
* semantics.c (maybe_add_lambda_conv_op): Clear DECL_NAME of copied
parms to avoid duplicate -Wshadow warnings.
diff --git a/gcc/cp/semantics.c b/gcc/cp/semantics.c
index 9d2f3f4..d39469d 100644
--- a/gcc/cp/semantics.c
+++ b/gcc/cp/semantics.c
@@ -9678,7 +9678,11 @@ maybe_add_lambda_conv_op (tree type)
DECL_STATIC_FUNCTION_P (fn) = 1;
DECL_ARGUMENTS (fn) = copy_list (DECL_CHAIN (DECL_ARGUMENTS (callop)));
for (arg = DECL_ARGUMENTS (fn); arg; arg = DECL_CHAIN (arg))
- DECL_CONTEXT (arg) = fn;
+ {
+ /* Avoid duplicate -Wshadow warnings. */
+ DECL_NAME (arg) = NULL_TREE;
+ DECL_CONTEXT (arg) = fn;
+ }
if (nested)
DECL_INTERFACE_KNOWN (fn) = 1;
diff --git a/gcc/testsuite/g++.dg/cpp0x/lambda/lambda-shadow1.C b/gcc/testsuite/g++.dg/cpp0x/lambda/lambda-shadow1.C
new file mode 100644
index 0000000..bb06bfe
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/lambda/lambda-shadow1.C
@@ -0,0 +1,9 @@
+// PR c++/55357
+// { dg-options "-std=c++11 -Wshadow" }
+
+int main() {
+ int x = 1; // { dg-warning "shadowed" }
+ auto const lambda = [](int x) { // { dg-warning "shadows" }
+ return x;
+ };
+}