Enforce consistent capitalization in diagnostic messages

Author: aviralg

include/swift/AST/DiagnosticsSema.def

@@ -8962,7 +8962,7 @@ GROUPED_WARNING(perf_hint_var_uses_existential,ExistentialType,DefaultIgnore,
                 "and dynamic dispatch. Consider using generic constraints or concrete types instead.",
                 (const VarDecl *))
 GROUPED_WARNING(perf_hint_any_pattern_uses_existential,ExistentialType,DefaultIgnore,
-                "Performance: Declaration uses an existential, leading to heap allocation, reference counting, "
+                "Performance: declaration uses an existential, leading to heap allocation, reference counting, "
                 "and dynamic dispatch. Consider using generic constraints or concrete types instead.",
                 ())
 GROUPED_WARNING(perf_hint_typealias_uses_existential,ExistentialType,DefaultIgnore,

test/PerformanceHints/existential-any.swift

@@ -140,7 +140,7 @@ func testCompoundTypes() {
 // Tuple
 ////////////////////////////////////////////////////////////////////////////////
 func tupleTest() {
-  let _ = ([Tiger() as any Animal], [Panda() as any Animal])  // expected-error {{Performance: Declaration uses an existential, leading to heap allocation, reference counting, and dynamic dispatch. Consider using generic constraints or concrete types instead.}}
+  let _ = ([Tiger() as any Animal], [Panda() as any Animal])  // expected-error {{Performance: declaration uses an existential, leading to heap allocation, reference counting, and dynamic dispatch. Consider using generic constraints or concrete types instead.}}
 
   let (
     animalsA,  // expected-error {{Performance: 'animalsA' uses an existential, leading to heap allocation, reference counting, and dynamic dispatch. Consider using generic constraints or concrete types instead.}}
@@ -150,13 +150,13 @@ func tupleTest() {
   print(type(of: animalsB))
 
   let (
-    _,  // expected-error {{Performance: Declaration uses an existential, leading to heap allocation, reference counting, and dynamic dispatch. Consider using generic constraints or concrete types instead.}}
+    _,  // expected-error {{Performance: declaration uses an existential, leading to heap allocation, reference counting, and dynamic dispatch. Consider using generic constraints or concrete types instead.}}
     animalsC  // expected-error {{Performance: 'animalsC' uses an existential, leading to heap allocation, reference counting, and dynamic dispatch. Consider using generic constraints or concrete types instead.}}
   ) = ([Tiger() as any Animal], [Panda() as any Animal])
 
   print(type(of: animalsC))
 
-  let (_, _) = ([Tiger() as any Animal], [Panda() as any Animal])  // expected-error 2 {{Performance: Declaration uses an existential, leading to heap allocation, reference counting, and dynamic dispatch. Consider using generic constraints or concrete types instead.}}
+  let (_, _) = ([Tiger() as any Animal], [Panda() as any Animal])  // expected-error 2 {{Performance: declaration uses an existential, leading to heap allocation, reference counting, and dynamic dispatch. Consider using generic constraints or concrete types instead.}}
 
   let tuple: (animal1: any Animal, animal2: any Animal) = (Tiger(), Panda())  // expected-error {{Performance: 'tuple' uses an existential, leading to heap allocation, reference counting, and dynamic dispatch. Consider using generic constraints or concrete types instead.}}
   print(type(of: tuple))