[clang] nonblocking/nonallocating attributes: 2nd pass caller/callee analysis (PR #99656)

[Doug Wyatt via cfe-commits]

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@@ -0,0 +1,256 @@
+// RUN: %clang_cc1 -fsyntax-only -fblocks -fcxx-exceptions -std=c++20 -verify %s
+// These are in a separate file because errors (e.g. incompatible attributes) currently prevent
+// the FXAnalysis pass from running at all.
+
+// This diagnostic is re-enabled and exercised in isolation later in this file.
+#pragma clang diagnostic ignored "-Wperf-constraint-implies-noexcept"
+
+// --- CONSTRAINTS ---
+
+void nb1() [[clang::nonblocking]]
+{
+	int *pInt = new int; // expected-warning {{'nonblocking' function must not allocate or deallocate memory}}
+	delete pInt; // expected-warning {{'nonblocking' function must not allocate or deallocate memory}}
+}
+
+void nb2() [[clang::nonblocking]]
+{
+	static int global; // expected-warning {{'nonblocking' function must not have static locals}}
+}
+
+void nb3() [[clang::nonblocking]]
+{
+	try {
+		throw 42; // expected-warning {{'nonblocking' function must not throw or catch exceptions}}
+	}
+	catch (...) { // expected-warning {{'nonblocking' function must not throw or catch exceptions}}
+	}
+}
+
----------------
dougsonos wrote:

OK, in the interest of not over-complicating things, I have not tried to detangle the way that default arguments are effectively visited twice, once at the function definition, and again at every call site.

There is however logic so that a warning pointing to a default argument is followed by a note at the call site which invoked it.

https://github.com/llvm/llvm-project/pull/99656