[Sema] Lambdas are not part of immediate context for deduction

This commit implements [temp.deduct]p9.
Test updates include:
- New notes in `cxx1y-init-captures.cpp`, `lambda-expressions.cpp`
  and 'warn-unused-lambda-capture.cpp'.
  This seems to be caused by diagnosing errors earlier (during
  deduction) that were previously surfaced later (during
  instantiation).
- New error `lambda-unevaluated.cpp` is in line with [temp.deduct]p9.

Reviewed By: erichkeane, #clang-language-wg

Differential Revision: https://reviews.llvm.org/D148802

1 files changed, 2 insertions, 0 deletions

diff --git a/clang/lib/Frontend/FrontendActions.cpp b/clang/lib/Frontend/FrontendActions.cpp
index c947772..f62a29c 100644
--- a/clang/lib/Frontend/FrontendActions.cpp
+++ b/clang/lib/Frontend/FrontendActions.cpp
@@ -372,6 +372,8 @@ private:
       return "ExplicitTemplateArgumentSubstitution";
     case CodeSynthesisContext::DeducedTemplateArgumentSubstitution:
       return "DeducedTemplateArgumentSubstitution";
+    case CodeSynthesisContext::LambdaExpressionSubstitution:
+      return "LambdaExpressionSubstitution";
     case CodeSynthesisContext::PriorTemplateArgumentSubstitution:
       return "PriorTemplateArgumentSubstitution";
     case CodeSynthesisContext::DefaultTemplateArgumentChecking: