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/Frontend/ASTUnit.cpp b/clang/lib/Frontend/ASTUnit.cpp
index 7226344..4fd330d 100644
--- a/clang/lib/Frontend/ASTUnit.cpp
+++ b/clang/lib/Frontend/ASTUnit.cpp
@@ -613,7 +613,7 @@
   // about. This effectively drops diagnostics from modules we're building.
   // FIXME: In the long run, ee don't want to drop source managers from modules.
   if (!Info.hasSourceManager() || &Info.getSourceManager() == SourceMgr)
-    StoredDiags.push_back(StoredDiagnostic(Level, Info));
+    StoredDiags.emplace_back(Level, Info);
 }
 
 ASTMutationListener *ASTUnit::getASTMutationListener() {