C++14 init-capture: error out instead of crashing.

When we have template arguments, we have a function and a pattern, the variable
in init-capture belongs to the pattern decl when checking if the lhs of
"max = current" is modifiable:
  auto find = [max = init](auto current) {
    max = current;
  };

In function isReferenceToNonConstCapture, we handle the case where the decl
context for the variable is not part of the current context.

Instead of crashing, we emit an error message:
cannot assign to a variable captured by copy in a non-mutable lambda

rdar://26997922

llvm-svn: 274392

1 files changed, 10 insertions, 0 deletions

diff --git a/clang/test/SemaCXX/cxx1y-init-captures.cpp b/clang/test/SemaCXX/cxx1y-init-captures.cpp
index d36882d8e5d..d681954707d 100644
--- a/clang/test/SemaCXX/cxx1y-init-captures.cpp
+++ b/clang/test/SemaCXX/cxx1y-init-captures.cpp
@@ -196,3 +196,13 @@ namespace N3922 {
   auto a = [x{X()}] { return x.n; }; // ok
   auto b = [x = {X()}] {}; // expected-error{{<initializer_list>}}
 }
+
+namespace init_capture_non_mutable {
+void test(double weight) {
+  double init;
+  auto find = [max = init](auto current) {
+    max = current; // expected-error{{cannot assign to a variable captured by copy in a non-mutable lambda}}
+  };
+  find(weight); // expected-note {{in instantiation of function template specialization}}
+}
+}