Migrate from SmallVector.set_size to resize_for_overwrite

In the "next" branch, set_size has been made protected. Instead, users
can use resize_for_overwrite, optionally followed by truncate, to
handle the same use cases more safely.

Author: benlangmuir

include/swift/Basic/DiverseStack.h

@@ -395,8 +395,7 @@ class DiverseValueBuffer {
 public:
   DiverseValueBuffer(const T &value) {
     size_t size = value.allocated_size();
-    data.reserve(size);
-    data.set_size(size);
+    data.resize_for_overwrite(size);
     memcpy(data.data(), reinterpret_cast<const void *>(&value), size);
   }
 

lib/IRGen/Explosion.h

@@ -45,8 +45,7 @@ class Explosion {
   Explosion &operator=(const Explosion &) = delete;
   Explosion(Explosion &&other) : NextValue(0) {
     // Do an uninitialized copy of the non-consumed elements.
-    Values.reserve(other.size());
-    Values.set_size(other.size());
+    Values.resize_for_overwrite(other.size());
     std::uninitialized_copy(other.begin(), other.end(), Values.begin());
 
     // Remove everything from the other explosion.

lib/IRGen/GenCall.cpp

@@ -3257,8 +3257,7 @@ void CallEmission::setFromCallee() {
 
   // Set up the args array.
   assert(Args.empty());
-  Args.reserve(numArgs);
-  Args.set_size(numArgs);
+  Args.resize_for_overwrite(numArgs);
   LastArgWritten = numArgs;
 }
 

lib/SIL/Utils/MemoryLocations.cpp

@@ -200,7 +200,7 @@ void MemoryLocations::analyzeLocation(SILValue loc) {
   SubLocationMap subLocationMap;
   if (!analyzeLocationUsesRecursively(loc, currentLocIdx, collectedVals,
                                       subLocationMap)) {
-    locations.set_size(currentLocIdx);
+    locations.truncate(currentLocIdx);
     for (SILValue V : collectedVals) {
       addr2LocIdx.erase(V);
     }

tools/SourceKit/tools/sourcekitd-repl/sourcekitd-repl.cpp

@@ -91,29 +91,29 @@ using Convert = ConvertForWcharSize<sizeof(wchar_t)>;
 static void convertFromUTF8(llvm::StringRef utf8,
                             llvm::SmallVectorImpl<wchar_t> &out) {
   size_t reserve = out.size() + utf8.size();
-  out.reserve(reserve);
+  out.resize_for_overwrite(reserve);
   const char *utf8_begin = utf8.begin();
   wchar_t *wide_begin = out.end();
   auto res = Convert::ConvertFromUTF8(&utf8_begin, utf8.end(),
                                       &wide_begin, out.data() + reserve,
                                       lenientConversion);
   assert(res == conversionOK && "utf8-to-wide conversion failed!");
   (void)res;
-  out.set_size(wide_begin - out.begin());
+  out.truncate(wide_begin - out.begin());
 }
 
 static void convertToUTF8(llvm::ArrayRef<wchar_t> wide,
                           llvm::SmallVectorImpl<char> &out) {
   size_t reserve = out.size() + wide.size()*4;
-  out.reserve(reserve);
+  out.resize_for_overwrite(reserve);
   const wchar_t *wide_begin = wide.begin();
   char *utf8_begin = out.end();
   auto res = Convert::ConvertToUTF8(&wide_begin, wide.end(),
                                     &utf8_begin, out.data() + reserve,
                                     lenientConversion);
   assert(res == conversionOK && "wide-to-utf8 conversion failed!");
   (void)res;
-  out.set_size(utf8_begin - out.begin());
+  out.truncate(utf8_begin - out.begin());
 }
 } // end anonymous namespace