From 572f0544a22a0526736ef043245268cd7da2d163 Mon Sep 17 00:00:00 2001
From: Anthony Latsis <aqamoss3fan2010@gmail.com>
Date: Mon, 23 Mar 2020 08:27:55 +0300
Subject: [PATCH] [DiagQoI] Improve fallback fixits for static member on
 instance error

---
 lib/Sema/CSDiagnostics.cpp              | 22 +++++++++++++---------
 test/NameBinding/name_lookup.swift      | 13 +++++++++++++
 test/Parse/enum.swift                   |  2 +-
 test/TypeCoercion/overload_member.swift |  4 ++--
 4 files changed, 29 insertions(+), 12 deletions(-)

diff --git a/lib/Sema/CSDiagnostics.cpp b/lib/Sema/CSDiagnostics.cpp
index 63b80ffeb5e..f8a10fa98a9 100644
--- a/lib/Sema/CSDiagnostics.cpp
+++ b/lib/Sema/CSDiagnostics.cpp
@@ -3708,15 +3708,19 @@ bool AllowTypeOrInstanceMemberFailure::diagnoseAsError() {
     }
 
     // Fall back to a fix-it with a full type qualifier
-    if (auto *NTD = Member->getDeclContext()->getSelfNominalTypeDecl()) {
-      auto type = NTD->getSelfInterfaceType();
-      if (auto *SE = dyn_cast<SubscriptExpr>(getRawAnchor())) {
-        auto *baseExpr = SE->getBase();
-        Diag->fixItReplace(baseExpr->getSourceRange(), diag::replace_with_type,
-                           type);
-      } else {
-        Diag->fixItInsert(loc, diag::insert_type_qualification, type);
-      }
+    const Expr *baseExpr = nullptr;
+    if (const auto SE = dyn_cast<SubscriptExpr>(getRawAnchor()))
+      baseExpr = SE->getBase();
+    else if (const auto UDE = dyn_cast<UnresolvedDotExpr>(getRawAnchor()))
+      baseExpr = UDE->getBase();
+
+    // An implicit 'self' reference base expression means we should
+    // prepend with qualification.
+    if (baseExpr && !baseExpr->isImplicit()) {
+      Diag->fixItReplace(baseExpr->getSourceRange(),
+                         diag::replace_with_type, baseTy);
+    } else {
+      Diag->fixItInsert(loc, diag::insert_type_qualification, baseTy);
     }
 
     return true;
diff --git a/test/NameBinding/name_lookup.swift b/test/NameBinding/name_lookup.swift
index fb5f62cf994..82881dfbaad 100644
--- a/test/NameBinding/name_lookup.swift
+++ b/test/NameBinding/name_lookup.swift
@@ -344,6 +344,19 @@ class ThisDerived1 : ThisBase1 {
   }
 }
 
+protocol Crawlable {}
+extension Crawlable {
+   static func crawl() {}
+}
+struct GenericChameleon<U>: Crawlable {
+  static func chameleon() {}
+
+  func testStaticOnInstance(arg: GenericChameleon<Never>) {
+    arg.chameleon() // expected-error {{static member 'chameleon' cannot be used on instance of type 'GenericChameleon<Never>'}} {{5-8=GenericChameleon<Never>}}
+    arg.crawl() // expected-error {{static member 'crawl' cannot be used on instance of type 'GenericChameleon<Never>'}} {{5-8=GenericChameleon<Never>}}
+  }
+}
+
 extension ThisBase1 {
   var baseExtProp : Int {
     get {
diff --git a/test/Parse/enum.swift b/test/Parse/enum.swift
index 3a51bfaa379..1d982946652 100644
--- a/test/Parse/enum.swift
+++ b/test/Parse/enum.swift
@@ -473,7 +473,7 @@ enum SE0036 {
 
   func staticReferenceInInstanceMethod() {
     _ = A // expected-error {{enum case 'A' cannot be used as an instance member}} {{9-9=SE0036.}}
-    _ = self.A // expected-error {{enum case 'A' cannot be used as an instance member}} {{9-9=SE0036.}}
+    _ = self.A // expected-error {{enum case 'A' cannot be used as an instance member}} {{9-13=SE0036}}
     _ = SE0036.A
   }
 
diff --git a/test/TypeCoercion/overload_member.swift b/test/TypeCoercion/overload_member.swift
index 4ebd3131fd7..84dc1482c18 100644
--- a/test/TypeCoercion/overload_member.swift
+++ b/test/TypeCoercion/overload_member.swift
@@ -69,7 +69,7 @@ func test_static_method_value_coerce(_ a: A) {
 func test_mixed_overload(_ a: A, x: X, y: Y) {
   var x1 = a.mixed(x: x)
   x1 = x
-  var y1 = a.mixed(y: y) // expected-error {{static member 'mixed' cannot be used on instance of type 'A'}} {{12-12=A.}}
+  var y1 = a.mixed(y: y) // expected-error {{static member 'mixed' cannot be used on instance of type 'A'}} {{12-13=A}}
   
   A.mixed(x) // expected-error{{cannot convert value of type 'X' to expected argument type 'A'}}
   var x2 = A.mixed(a)(x: x)
@@ -89,7 +89,7 @@ func test_mixed_overload_coerce(_ a: A, x: inout X, y: Y, z: Z) {
 func test_mixed_method_value_coerce(_ a: A) {
   var _ : (X) -> X = a.mixed
   var _ : (Y) -> Y = A.mixed
-  var _ : (Y) -> Y = a.mixed; // expected-error {{static member 'mixed' cannot be used on instance of type 'A'}} {{22-22=A.}}
+  var _ : (Y) -> Y = a.mixed; // expected-error {{static member 'mixed' cannot be used on instance of type 'A'}} {{22-23=A}}
   var _ : (A) -> (X) -> X = A.mixed
 }