From 6c6fba8808e6e576ee8259b7699e3e4fd545d0bb Mon Sep 17 00:00:00 2001
From: Sterling Augustine <saugustine@google.com>
Date: Wed, 25 Mar 2020 18:09:25 -0700
Subject: [PATCH] Correctly handle using foo = std::foo inside namespaces.

Summary:
The gdb pretty printer misprints variables declared via
using declarations of the form:

namespace foo {
using string_view = std::string_view;

string_view bar;
}

This change fixes that, by deferring the decision to ignore
types not inside std until after desugaring.

Reviewers: #libc!

Subscribers: broadwaylamb, libcxx-commits

Tags: #libc

Differential Revision: https://reviews.llvm.org/D76816
---
 .../pretty_printers/gdb_pretty_printer_test.sh.cpp     | 18 +++++++++++++++++-
 libcxx/utils/gdb/libcxx/printers.py                    |  8 ++++----
 2 files changed, 21 insertions(+), 5 deletions(-)

diff --git a/libcxx/test/pretty_printers/gdb_pretty_printer_test.sh.cpp b/libcxx/test/pretty_printers/gdb_pretty_printer_test.sh.cpp
index 3050cf1..093fa4f 100644
--- a/libcxx/test/pretty_printers/gdb_pretty_printer_test.sh.cpp
+++ b/libcxx/test/pretty_printers/gdb_pretty_printer_test.sh.cpp
@@ -153,6 +153,16 @@ void string_test() {
                             "\"mehmet bizim dostumuz agzi kirik testimiz\"");
 }
 
+namespace a_namespace {
+// To test name-lookup in the presence of using inside a namespace. Inside this
+// namespace, unqualified string_view variables will appear in the debug info as
+// "a_namespace::string_view, rather than "std::string_view".
+//
+// There is nothing special here about string_view; it's just the data structure
+// where lookup with using inside a namespace wasn't always working.
+
+using string_view = std::string_view;
+
 void string_view_test() {
   std::string_view i_am_empty;
   ComparePrettyPrintToChars(i_am_empty, "std::string_view of length 0: \"\"");
@@ -166,6 +176,12 @@ void string_view_test() {
   std::string_view wonderful(&char_arr[7], 9);
   ComparePrettyPrintToChars(
       wonderful, "std::string_view of length 9: \"wonderful\"");
+
+  const char char_arr1[] = "namespace_stringview";
+  string_view namespace_stringview(&char_arr1[10], 10);
+  ComparePrettyPrintToChars(
+      namespace_stringview, "std::string_view of length 10: \"stringview\"");
+}
 }
 
 void u16string_test() {
@@ -628,7 +644,7 @@ int main(int argc, char* argv[]) {
   framework_self_test();
 
   string_test();
-  string_view_test();
+  a_namespace::string_view_test();
 
   u32string_test();
   tuple_test();
diff --git a/libcxx/utils/gdb/libcxx/printers.py b/libcxx/utils/gdb/libcxx/printers.py
index 4b724c9..7cccc079 100644
--- a/libcxx/utils/gdb/libcxx/printers.py
+++ b/libcxx/utils/gdb/libcxx/printers.py
@@ -982,10 +982,10 @@ class LibcxxPrettyPrinter(object):
         # Don't attempt types known to be inside libstdcxx.
         typename = val.type.name or val.type.tag or str(val.type)
         match = re.match("^std::(__.*?)::", typename)
-        if match is None or match.group(1) in ["__cxx1998",
-                                               "__debug",
-                                               "__7",
-                                               "__g"]:
+        if match is not None and match.group(1) in ["__cxx1998",
+                                                    "__debug",
+                                                    "__7",
+                                                    "__g"]:
             return None
 
         # Handle any using declarations or other typedefs.
-- 
2.7.4