[Sema][Diagnostics] Add fixit for warning when inferring an undesirable type

Author: jder

lib/Sema/TypeCheckPattern.cpp

@@ -1018,8 +1018,8 @@ bool TypeChecker::coercePatternToType(Pattern *&P, TypeResolution resolution,
         !(options & TypeResolutionFlags::FromNonInferredPattern)) {
       diags.diagnose(NP->getLoc(), diag, NP->getDecl()->getName(), type,
                      NP->getDecl()->isLet());
-      diags.diagnose(NP->getLoc(),
-                     diag::add_explicit_type_annotation_to_silence);
+      diags.diagnose(NP->getLoc(), diag::add_explicit_type_annotation_to_silence)
+          .fixItInsertAfter(var->getNameLoc(), ": " + type->getString());
     }
 
     return false;

test/decl/var/lazy_properties.swift

@@ -112,7 +112,7 @@ struct Outer {
 
     lazy var y = {_ = 3}()
     // expected-warning@-1 {{variable 'y' inferred to have type '()', which may be unexpected}}
-    // expected-note@-2 {{add an explicit type annotation to silence this warning}}
+    // expected-note@-2 {{add an explicit type annotation to silence this warning}} {{15-15=: ()}}
   }
 }
 

test/decl/var/properties.swift

@@ -1272,11 +1272,11 @@ class WeakFixItTest {
 
 // SR-8811 (Warning)
 
-let sr8811a = fatalError() // expected-warning {{constant 'sr8811a' inferred to have type 'Never', which is an enum with no cases}} expected-note {{add an explicit type annotation to silence this warning}}
+let sr8811a = fatalError() // expected-warning {{constant 'sr8811a' inferred to have type 'Never', which is an enum with no cases}} expected-note {{add an explicit type annotation to silence this warning}} {{12-12=: Never}}
 
 let sr8811b: Never = fatalError() // Ok
 
-let sr8811c = (16, fatalError()) // expected-warning {{constant 'sr8811c' inferred to have type '(Int, Never)', which contains an enum with no cases}} expected-note {{add an explicit type annotation to silence this warning}}
+let sr8811c = (16, fatalError()) // expected-warning {{constant 'sr8811c' inferred to have type '(Int, Never)', which contains an enum with no cases}} expected-note {{add an explicit type annotation to silence this warning}} {{12-12=: (Int, Never)}}
 
 let sr8811d: (Int, Never) = (16, fatalError()) // Ok
 
@@ -1292,11 +1292,11 @@ class SR_10995 {
   }
 
   func sr_10995_foo() {
-    let doubleOptionalNever = makeDoubleOptionalNever() // expected-warning {{constant 'doubleOptionalNever' inferred to have type 'Never??', which may be unexpected}} 
-    // expected-note@-1 {{add an explicit type annotation to silence this warning}} 
+    let doubleOptionalNever = makeDoubleOptionalNever() // expected-warning {{constant 'doubleOptionalNever' inferred to have type 'Never??', which may be unexpected}}
+    // expected-note@-1 {{add an explicit type annotation to silence this warning}} {{28-28=: Never??}}
     // expected-warning@-2 {{initialization of immutable value 'doubleOptionalNever' was never used; consider replacing with assignment to '_' or removing it}}
     let singleOptionalNever = makeSingleOptionalNever() // expected-warning {{constant 'singleOptionalNever' inferred to have type 'Never?', which may be unexpected}} 
-    // expected-note@-1 {{add an explicit type annotation to silence this warning}} 
+    // expected-note@-1 {{add an explicit type annotation to silence this warning}} {{28-28=: Never?}}
     // expected-warning@-2 {{initialization of immutable value 'singleOptionalNever' was never used; consider replacing with assignment to '_' or removing it}}
   }
 }

test/decl/var/variables.swift

@@ -36,15 +36,15 @@ struct Broken {
 
 // rdar://16252090 - Warning when inferring empty tuple type for declarations
 var emptyTuple = testShadowing()  // expected-warning {{variable 'emptyTuple' inferred to have type '()'}} \
-                                  // expected-note {{add an explicit type annotation to silence this warning}}
+                                  // expected-note {{add an explicit type annotation to silence this warning}} {{15-15=: ()}}
 
 // rdar://15263687 - Diagnose variables inferenced to 'AnyObject'
 var ao1 : AnyObject
 var ao2 = ao1
 
 var aot1 : AnyObject.Type
 var aot2 = aot1          // expected-warning {{variable 'aot2' inferred to have type 'AnyObject.Type', which may be unexpected}} \
-                       // expected-note {{add an explicit type annotation to silence this warning}}
+                       // expected-note {{add an explicit type annotation to silence this warning}} {{9-9=: AnyObject.Type}}
 
 
 for item in [AnyObject]() {  // No warning in for-each loop.

test/expr/expressions.swift

@@ -588,9 +588,9 @@ func conversionTest(_ a: inout Double, b: inout Int) {
   var pi_f3 = float.init(getPi()) // expected-error {{ambiguous use of 'init(_:)'}}
   var pi_f4 = float.init(pi_f)
 
-  var e = Empty(f) // expected-warning {{variable 'e' inferred to have type 'Empty', which is an enum with no cases}} expected-note {{add an explicit type annotation to silence this warning}}
+  var e = Empty(f) // expected-warning {{variable 'e' inferred to have type 'Empty', which is an enum with no cases}} expected-note {{add an explicit type annotation to silence this warning}}  {{8-8=: Empty}}
   var e2 = Empty(d) // expected-error{{cannot convert value of type 'Double' to expected argument type 'Float'}}
-  var e3 = Empty(Float(d)) // expected-warning {{variable 'e3' inferred to have type 'Empty', which is an enum with no cases}} expected-note {{add an explicit type annotation to silence this warning}}
+  var e3 = Empty(Float(d)) // expected-warning {{variable 'e3' inferred to have type 'Empty', which is an enum with no cases}} expected-note {{add an explicit type annotation to silence this warning}}  {{9-9=: Empty}}
 }
 
 struct Rule {