Replace push_back(Constructor(foo)) with emplace_back(foo) for non-trivial types

If the type isn't trivially moveable emplace can skip a potentially
expensive move. It also saves a couple of characters.


Call sites were found with the ASTMatcher + some semi-automated cleanup.

memberCallExpr(
    argumentCountIs(1), callee(methodDecl(hasName("push_back"))),
    on(hasType(recordDecl(has(namedDecl(hasName("emplace_back")))))),
    hasArgument(0, bindTemporaryExpr(
                       hasType(recordDecl(hasNonTrivialDestructor())),
                       has(constructExpr()))),
    unless(isInTemplateInstantiation()))

No functional change intended.

llvm-svn: 238601
diff --git a/clang/lib/Driver/Driver.cpp b/clang/lib/Driver/Driver.cpp
index 65d0049..88c76ea 100644
--- a/clang/lib/Driver/Driver.cpp
+++ b/clang/lib/Driver/Driver.cpp
@@ -1878,8 +1878,8 @@
 Driver::generatePrefixedToolNames(const char *Tool, const ToolChain &TC,
                                   SmallVectorImpl<std::string> &Names) const {
   // FIXME: Needs a better variable than DefaultTargetTriple
-  Names.push_back(DefaultTargetTriple + "-" + Tool);
-  Names.push_back(Tool);
+  Names.emplace_back(DefaultTargetTriple + "-" + Tool);
+  Names.emplace_back(Tool);
 }
 
 static bool ScanDirForExecutable(SmallString<128> &Dir,