[GNU ObjC] Fix a regression listing methods twice.

Methods synthesized from declared properties were being added to the
method lists twice.  This came from the change to list them in the
class's method list, which missed removing the place in CGObjCGNU that
added them again.

Reviewed By: lanza

Differential Revision: https://reviews.llvm.org/D91874

(cherry picked from commit d1ed67037de6f3f44dc446784f74f0e02adec9b5)

1 files changed, 23 insertions, 0 deletions

diff --git a/clang/test/CodeGenObjC/gnu-method-only-once.m b/clang/test/CodeGenObjC/gnu-method-only-once.m
new file mode 100644
index 000000000000..67d873ccc0aa
--- /dev/null
+++ b/clang/test/CodeGenObjC/gnu-method-only-once.m
@@ -0,0 +1,23 @@
+// RUN: %clang_cc1 -triple x86_64-unknown-freebsd -S -emit-llvm -fobjc-runtime=gnustep-2.0 -o - %s | FileCheck %s -check-prefix=CHECK-NEW
+// RUN: %clang_cc1 -triple x86_64-unknown-freebsd -S -emit-llvm -fobjc-runtime=gnustep-1.8 -o - %s | FileCheck %s -check-prefix=CHECK-OLD
+
+// Clang 9 or 10 changed the handling of method lists so that methods provided
+// from synthesised properties showed up in the method list, where previously
+// CGObjCGNU had to collect them and merge them.  One of the places where this
+// merging happened was missed in the move and so we ended up emitting two
+// copies of method metadata for declared properties.
+
+// This class has only instance properties and only one pair of synthesized
+// methods from the property and so we should synthesize only one method list,
+// with precisely two methods on it.
+@interface X
+@property (retain) id iProp;
+@end
+
+@implementation X
+@synthesize iProp;
+@end
+
+// Check that the method list has precisely 2 methods.
+// CHECK-NEW: @.objc_method_list = internal global { i8*, i32, i64, [2 x
+// CHECK-OLD: @.objc_method_list = internal global { i8*, i32, [2 x