[ASTPrinter] Fix issue where printing if-let variables shows their type as optional

lib/AST/ASTPrinter.cpp

@@ -2612,9 +2612,17 @@ void PrintAST::visitVarDecl(VarDecl *decl) {
   auto type = decl->getInterfaceType();
   Printer << ": ";
   TypeLoc tyLoc;
-  if (auto *repr = decl->getTypeReprOrParentPatternTypeRepr())
+  if (auto *repr = decl->getTypeReprOrParentPatternTypeRepr()) {
+    // Workaround for if-let statements. The parser creates a `OptionalTypeRepr`
+    // even though the user-written declared type for the if-let variable
+    // is non-optional. Get the non-optional type so we can print it correctly.
+    if (auto *optRepr = dyn_cast<OptionalTypeRepr>(repr)) {
+      if (type && !isa<OptionalType>(type.getPointer())) {
+        repr = optRepr->getBase();
+      }
+    }
     tyLoc = TypeLoc(repr, type);
-  else
+  } else
     tyLoc = TypeLoc::withoutLoc(type);
 
   Printer.printDeclResultTypePre(decl, tyLoc);

lib/Parse/ParsePattern.cpp

@@ -1154,6 +1154,10 @@ parseOptionalPatternTypeAnnotation(ParserResult<Pattern> result,
 
   // In an if-let, the actual type of the expression is Optional of whatever
   // was written.
+  // FIXME: This is not good, `TypeRepr`s are supposed to represent what the
+  // user actually wrote in source (that's why they don't have any `isImplicit`
+  // bit). This synthesized `OptionalTypeRepr` leads to workarounds in other
+  // parts where we want to reason about the types as perceived by the user.
   if (isOptional)
     repr = new (Context) OptionalTypeRepr(repr, SourceLoc());
 

test/SourceKit/CursorInfo/sr-12631-if-let-type.swift

@@ -0,0 +1,14 @@
+let foo: Int? = 123
+if let bar: Int = foo {
+  _ = bar
+}
+
+// RUN: %sourcekitd-test -req=cursor -pos=2:8 %s -- %s | %FileCheck --check-prefix=CHECK-BAR %s
+// RUN: %sourcekitd-test -req=cursor -pos=3:7 %s -- %s | %FileCheck --check-prefix=CHECK-BAR %s
+// RUN: %sourcekitd-test -req=cursor -pos=1:5 %s -- %s | %FileCheck --check-prefix=CHECK-FOO %s
+
+// CHECK-BAR:      <Declaration>let bar: <Type usr="s:Si">Int</Type></Declaration>
+// CHECK-BAR-NEXT: <decl.var.local><syntaxtype.keyword>let</syntaxtype.keyword> <decl.name>bar</decl.name>: <decl.var.type><ref.struct usr="s:Si">Int</ref.struct></decl.var.type></decl.var.local>
+
+// CHECK-FOO:      <Declaration>let foo: <Type usr="s:Si">Int</Type>?</Declaration>
+// CHECK-FOO-NEXT: <decl.var.global><syntaxtype.keyword>let</syntaxtype.keyword> <decl.name>foo</decl.name>: <decl.var.type><ref.struct usr="s:Si">Int</ref.struct>?</decl.var.type></decl.var.global>