[clang] Add tests for CWG issues 6, 212, 232, 2823. (PR #165633)

[Richard Smith via cfe-commits]

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@@ -0,0 +1,31 @@
+// RUN: %clang_cc1 -std=c++98 %s -triple x86_64-linux-gnu -emit-llvm -o - -fexceptions -fcxx-exceptions -pedantic-errors | FileCheck %s --check-prefixes CHECK
+// RUN: %clang_cc1 -std=c++11 %s -triple x86_64-linux-gnu -emit-llvm -o - -fexceptions -fcxx-exceptions -pedantic-errors | FileCheck %s --check-prefixes CHECK
+// RUN: %clang_cc1 -std=c++14 %s -triple x86_64-linux-gnu -emit-llvm -o - -fexceptions -fcxx-exceptions -pedantic-errors | FileCheck %s --check-prefixes CHECK
+// RUN: %clang_cc1 -std=c++17 %s -triple x86_64-linux-gnu -emit-llvm -o - -fexceptions -fcxx-exceptions -pedantic-errors | FileCheck %s --check-prefixes CHECK
+// RUN: %clang_cc1 -std=c++20 %s -triple x86_64-linux-gnu -emit-llvm -o - -fexceptions -fcxx-exceptions -pedantic-errors | FileCheck %s --check-prefixes CHECK
+// RUN: %clang_cc1 -std=c++23 %s -triple x86_64-linux-gnu -emit-llvm -o - -fexceptions -fcxx-exceptions -pedantic-errors | FileCheck %s --check-prefixes CHECK
+// RUN: %clang_cc1 -std=c++2c %s -triple x86_64-linux-gnu -emit-llvm -o - -fexceptions -fcxx-exceptions -pedantic-errors | FileCheck %s --check-prefixes CHECK
+
+namespace cwg6 { // cwg6: yes
+
+struct A {
+  A();
+  A(const A&);
+  ~A();
+};
+
+inline void f(A a) {}
+
+// CHECK-LABEL: define {{.*}} @_ZN4cwg64callEv
+void call() {
+  A a;
+  // We copy the parameter here, even though object is not mutated by f and
+  // otherwise satisfies the criteria for the proposed CWG6 optimization.
+  // CHECK: {{call|invoke}} {{.*}} @_ZN4cwg61AC1ERKS0_
+  // CHECK: {{call|invoke}} {{.*}} @_ZN4cwg61fE
+  f(a);
+  // CHECK: {{call|invoke}} {{.*}} @_ZN4cwg61AD1Ev
+  // CHECK: {{call|invoke}} {{.*}} @_ZN4cwg61AD1Ev
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zygoloid wrote:

Unfortunately that doesn't work directly. Because destructors aren't non-throwing in C++98, the first call is actually a `call` not an `invoke` in C++98. I've marked all these functions as non-throwing instead, to avoid the test noise from exception handling.

https://github.com/llvm/llvm-project/pull/165633