From 686e4a600cd1c076b2a6b698adbdd54247ce6617 Mon Sep 17 00:00:00 2001
From: Owen Voorhees <owen@squibner.com>
Date: Sun, 4 Aug 2019 17:57:54 -0700
Subject: [PATCH] Assign a SourceLoc to implicit appendInterpolation calls for
 diagnostics

This helps ensure that if, for example, a deprecated appendInterpolation is used, the resulting diag points to the opening paren of the corresponding string interpolation segment
---
 lib/Parse/ParseExpr.cpp                       | 10 ++++----
 ...diag_deprecated_string_interpolation.swift | 24 +++++++++++++++++++
 2 files changed, 29 insertions(+), 5 deletions(-)
 create mode 100644 test/Sema/diag_deprecated_string_interpolation.swift

diff --git a/lib/Parse/ParseExpr.cpp b/lib/Parse/ParseExpr.cpp
index b04f7e9185280..a7fc42efce400 100644
--- a/lib/Parse/ParseExpr.cpp
+++ b/lib/Parse/ParseExpr.cpp
@@ -1855,11 +1855,11 @@ parseStringSegments(SmallVectorImpl<Lexer::StringSegment> &Segments,
       TokReceiver->registerTokenKindChange(Tok.getLoc(),
                                            tok::string_interpolation_anchor);
 
-      auto callee = new (Context) UnresolvedDotExpr(InterpolationVarRef,
-                                                    /*dotloc=*/BackSlashLoc,
-                                                    appendInterpolation,
-                                                    /*nameloc=*/DeclNameLoc(),
-                                                    /*Implicit=*/true);
+      auto callee = new (Context)
+          UnresolvedDotExpr(InterpolationVarRef,
+                            /*dotloc=*/BackSlashLoc, appendInterpolation,
+                            /*nameloc=*/DeclNameLoc(Segment.Loc),
+                            /*Implicit=*/true);
       auto S = parseExprCallSuffix(makeParserResult(callee), true);
 
       // If we stopped parsing the expression before the expression segment is
diff --git a/test/Sema/diag_deprecated_string_interpolation.swift b/test/Sema/diag_deprecated_string_interpolation.swift
new file mode 100644
index 0000000000000..61aa2944d3b6d
--- /dev/null
+++ b/test/Sema/diag_deprecated_string_interpolation.swift
@@ -0,0 +1,24 @@
+// RUN: %target-swift-frontend -swift-version 5 -typecheck %s 2>&1 | %FileCheck %s
+
+extension DefaultStringInterpolation {
+    @available(*, deprecated) func appendInterpolation(deprecated: Int) {}
+}
+
+// Make sure diagnostics emitted via string interpolations have a reasonable source location
+
+_ = "\(deprecated: 42)"
+// CHECK: [[@LINE-1]]:7: warning: 'appendInterpolation(deprecated:)' is deprecated
+
+_ = "hello, world\(deprecated: 42)!!!"
+// CHECK: [[@LINE-1]]:19: warning: 'appendInterpolation(deprecated:)' is deprecated
+
+_ = "\(42)\(deprecated: 42)test\(deprecated: 42)"
+// CHECK: [[@LINE-1]]:12: warning: 'appendInterpolation(deprecated:)' is deprecated
+// CHECK: [[@LINE-2]]:33: warning: 'appendInterpolation(deprecated:)' is deprecated
+
+_ = """
+This is a multiline literal with a deprecated interpolation:
+
+\(deprecated: 42)
+"""
+// CHECK: [[@LINE-2]]:2: warning: 'appendInterpolation(deprecated:)' is deprecated