[clang-tidy] add regression test to performance-unnecessary-value-param

This test shows the problem in https://bugs.llvm.org/show_bug.cgi?id=33734

Differential Revision: https://reviews.llvm.org/D35225

llvm-svn: 307810

clang-tools-extra/test/clang-tidy/Inputs/performance-unnecessary-value-param/header-fixed.h

@@ -0,0 +1,15 @@
+// struct ABC is expensive to copy and should be
+// passed as a const referece.
+struct ABC {
+  ABC(const ABC&);
+  int get(int) const;
+};
+
+
+int f1(int n,              const ABC& v1,   const ABC& v2); // line 9
+
+int f1(int n, ABC v1); // line 11
+
+
+
+int f2(        int n,       const ABC& v2); // line 15

clang-tools-extra/test/clang-tidy/Inputs/performance-unnecessary-value-param/header.h

@@ -0,0 +1,15 @@
+// struct ABC is expensive to copy and should be
+// passed as a const referece.
+struct ABC {
+  ABC(const ABC&);
+  int get(int) const;
+};
+
+
+int f1(int n,              ABC v1,   ABC v2); // line 9
+
+int f1(int n, ABC v1); // line 11
+
+
+
+int f2(        int n,       ABC v2); // line 15

clang-tools-extra/test/clang-tidy/performance-unnecessary-value-param-header.cpp

@@ -0,0 +1,18 @@
+// RUN: cp %S/Inputs/performance-unnecessary-value-param/header.h %T/header.h
+// RUN: %check_clang_tidy %s performance-unnecessary-value-param %t -- -- -std=c++11 -I %T
+// RUN: diff %T/header.h %S/Inputs/performance-unnecessary-value-param/header-fixed.h
+
+#include "header.h"
+
+
+
+int f1(int n, ABC v1, ABC v2) {
+  // CHECK-MESSAGES: [[@LINE-1]]:19: warning: the parameter 'v1' is copied for each invocation but only used as a const reference; consider making it a const reference [performance-unnecessary-value-param]
+  // CHECK-MESSAGES: [[@LINE-2]]:27: warning: the parameter 'v2' is copied for each invocation but only used as a const reference; consider making it a const reference [performance-unnecessary-value-param]
+  // CHECK-FIXES: int f1(int n, const ABC& v1, const ABC& v2) {
+  return v1.get(n) + v2.get(n);
+}
+int f2(int n, ABC v2) {
+  // CHECK-MESSAGES: [[@LINE-1]]:19: warning: the parameter 'v2' is copied for each invocation but only used as a const reference; consider making it a const reference [performance-unnecessary-value-param]
+  // CHECK-FIXES: int f2(int n, const ABC& v2) {
+}