Various clang tidy warning fixes (#448)

* Fixed clang-tidy bugprone-reserved-identifier warnings

* Fixed clang-tidy bugprone-assert-side-effect warnings

* Fixed clang-tidy bugprone-copy-constructor-init warning

* Fixed clang-tidy readability-redundant-preprocessor warning

For error_test.c the removed code was already dead, because it was in the else of an `#if H5_USE_16_API` block.

Based on H5Location.h, I think p_get_ref_obj_type was meant to be in `#ifndef DOXYGEN_SHOULD_SKIP_THIS` and an `#endif` was missing.  Similarly, in the header, getObjTypeByIdx is only in H5_NO_DEPRECATED_SYMBOLS, not DOXYGEN_SHOULD_SKIP_THIS.

* Fixed clang-tidy readability-redundant-string-init warnings

* Fixed some clang-tidy performance-type-promotion-in-math-fn warnings

* Fixed clang-tidy performance-unnecessary-value-param warnings

* Reformat source with clang v10.0.1.

Co-authored-by: Larry Knox <lrknox@hdfgroup.org>

1 files changed, 1 insertions, 1 deletions

diff --git a/c++/src/H5DxferProp.cpp b/c++/src/H5DxferProp.cpp
index d9d7884..98e6214 100644
--- a/c++/src/H5DxferProp.cpp
+++ b/c++/src/H5DxferProp.cpp
@@ -306,7 +306,7 @@ DSetMemXferPropList::getDataTransform() const
 {
     // Initialize string to "", so that if there is no expression, the returned
     // string will be empty
-    H5std_string expression("");
+    H5std_string expression;
 
     // Preliminary call to get the expression's length
     ssize_t exp_len = H5Pget_data_transform(id, NULL, (size_t)0);