[clang][ExtractAPI] Fix appendSpace in DeclarationFragments

There is a bug in `DeclarationFragments::appendSpace` where the space
character is added to a local copy of the last fragment.

Differential Revision: https://reviews.llvm.org/D123259

clang/lib/ExtractAPI/DeclarationFragments.cpp

@@ -21,7 +21,7 @@ using namespace llvm;
 
 DeclarationFragments &DeclarationFragments::appendSpace() {
   if (!Fragments.empty()) {
-    Fragment Last = Fragments.back();
+    Fragment &Last = Fragments.back();
     if (Last.Kind == FragmentKind::Text) {
       // Merge the extra space into the last fragment if the last fragment is
       // also text.
@@ -390,7 +390,7 @@ DeclarationFragmentsBuilder::getFragmentsForParam(const ParmVarDecl *Param) {
   if (Param->isObjCMethodParameter())
     Fragments.append("(", DeclarationFragments::FragmentKind::Text)
         .append(std::move(TypeFragments))
-        .append(")", DeclarationFragments::FragmentKind::Text);
+        .append(") ", DeclarationFragments::FragmentKind::Text);
   else
     Fragments.append(std::move(TypeFragments)).appendSpace();
 

clang/test/ExtractAPI/global_record.c

@@ -175,7 +175,7 @@ char unavailable __attribute__((unavailable));
         },
         {
           "kind": "text",
-          "spelling": " *"
+          "spelling": " * "
         },
         {
           "kind": "internalParam",
@@ -331,7 +331,7 @@ char unavailable __attribute__((unavailable));
               },
               {
                 "kind": "text",
-                "spelling": " *"
+                "spelling": " * "
               },
               {
                 "kind": "internalParam",

clang/test/ExtractAPI/global_record_multifile.c

@@ -177,7 +177,7 @@ char unavailable __attribute__((unavailable));
         },
         {
           "kind": "text",
-          "spelling": " *"
+          "spelling": " * "
         },
         {
           "kind": "internalParam",
@@ -333,7 +333,7 @@ char unavailable __attribute__((unavailable));
               },
               {
                 "kind": "text",
-                "spelling": " *"
+                "spelling": " * "
               },
               {
                 "kind": "internalParam",

clang/test/ExtractAPI/macro_undefined.c

@@ -142,7 +142,7 @@ FUNC_GEN(bar, const int *, unsigned);
         },
         {
           "kind": "text",
-          "spelling": " *"
+          "spelling": " * "
         },
         {
           "kind": "internalParam",
@@ -189,7 +189,7 @@ FUNC_GEN(bar, const int *, unsigned);
               },
               {
                 "kind": "text",
-                "spelling": " *"
+                "spelling": " * "
               },
               {
                 "kind": "internalParam",

clang/test/ExtractAPI/objc_category.m

@@ -131,7 +131,7 @@
         },
         {
           "kind": "text",
-          "spelling": ")"
+          "spelling": ") "
         },
         {
           "kind": "identifier",
@@ -185,7 +185,7 @@
         },
         {
           "kind": "text",
-          "spelling": ")"
+          "spelling": ") "
         },
         {
           "kind": "identifier",
@@ -266,7 +266,7 @@
         },
         {
           "kind": "text",
-          "spelling": ")"
+          "spelling": ") "
         },
         {
           "kind": "typeIdentifier",

clang/test/ExtractAPI/objc_interface.m

@@ -142,7 +142,7 @@
         },
         {
           "kind": "text",
-          "spelling": ")"
+          "spelling": ") "
         },
         {
           "kind": "identifier",
@@ -163,7 +163,7 @@
         },
         {
           "kind": "text",
-          "spelling": ")"
+          "spelling": ") "
         },
         {
           "kind": "internalParam",
@@ -244,7 +244,7 @@
         },
         {
           "kind": "text",
-          "spelling": ")"
+          "spelling": ") "
         },
         {
           "kind": "typeIdentifier",
@@ -398,7 +398,7 @@
         },
         {
           "kind": "text",
-          "spelling": ")"
+          "spelling": ") "
         },
         {
           "kind": "identifier",