[clang] [Clang][OpenMP] Validate prefer_type fr()/attr() arguments in append_args clause (PR #212307)

[Zahira Ammarguellat via cfe-commits]

================
@@ -0,0 +1,59 @@
+// RUN: %clang_cc1 -verify -fopenmp -fopenmp-version=60 -std=c++11 -o - %s
+
+typedef void *omp_interop_t;
+
+void foo_v1(float *A, float *B, omp_interop_t IOp);
+
+// expected-error at +2 {{prefer_list item must be a string literal or constant integral expression}}
+#pragma omp declare variant(foo_v1) match(construct={dispatch}) \
+  append_args(interop(prefer_type({fr(1.0)}), target))
+void foo_fr_float(float *A, float *B) {}
+
+void bar_v1(float *A, omp_interop_t IOp);
+
+// expected-error at +2 {{attr() argument must be a string literal}}
+#pragma omp declare variant(bar_v1) match(construct={dispatch}) \
+  append_args(interop(prefer_type({attr(1)}), target))
+void bar_attr_int(float *A) {}
+
+void baz_v1(float *A, omp_interop_t IOp);
+
+// expected-error at +2 {{attr() argument 'cuda_prop' must start with the 'ompx_' prefix}}
+#pragma omp declare variant(baz_v1) match(construct={dispatch}) \
+  append_args(interop(prefer_type({attr("cuda_prop")}), target))
+void baz_attr_no_prefix(float *A) {}
+
+void qux_v1(float *A, omp_interop_t IOp);
+
+// expected-error at +2 {{attr() argument 'ompx_a,b' must not contain a comma}}
+#pragma omp declare variant(qux_v1) match(construct={dispatch}) \
+  append_args(interop(prefer_type({attr("ompx_a,b")}), target))
+void qux_attr_comma(float *A) {}
+
+// Valid cases -- no diagnostics expected.
+void valid_v1(float *A, omp_interop_t IOp);
+
+#pragma omp declare variant(valid_v1) match(construct={dispatch}) \
+  append_args(interop(prefer_type({fr("cuda")}), target))
+void valid_fr_string(float *A) {}
+
+void valid_v2(float *A, omp_interop_t IOp);
+
+#pragma omp declare variant(valid_v2) match(construct={dispatch}) \
+  append_args(interop(prefer_type({fr(1)}), target))
+void valid_fr_int(float *A) {}
+
+void valid_v3(float *A, omp_interop_t IOp);
+
+#pragma omp declare variant(valid_v3) match(construct={dispatch}) \
+  append_args(interop(prefer_type({attr("ompx_myattr")}), target))
+void valid_attr(float *A) {}
+
+// Template case: fr() argument becomes invalid at instantiation.
+template <typename T>
+void tmpl_v1(T *A, omp_interop_t IOp);
+
+// expected-error at +2 {{prefer_list item must be a string literal or constant integral expression}}
+#pragma omp declare variant(tmpl_v1<int>) match(construct={dispatch}) \
+  append_args(interop(prefer_type({fr(1.5)}), target))
+void tmpl_fr_invalid(int *A) {}
----------------
zahiraam wrote:

Can you add:

 ```
void valid_v4(float *A, omp_interop_t IOp);                                                                                                                                            
  #pragma omp declare variant(valid_v4) match(construct={dispatch}) \                                                                                                                            
    append_args(interop(prefer_type({attr("ompx_prop")}), target))                                                                                                 
  void valid_attr_only(float *A) {}
```
```
void valid_v5(float *A, omp_interop_t IOp);                                                                                                                                                                  
  #pragma omp declare variant(valid_v5) match(construct={dispatch}) \                                                                                                                                          
    append_args(interop(prefer_type({fr(1), attr("ompx_prop")}), target))                                                                                                                                      
  void valid_combined(float *A) {}
```
Consider adding some edge cases:  empty string: attr("") or fr("") , or just prefix: attr("ompx_") or multiple commas: attr("ompx_a,b,c").

https://github.com/llvm/llvm-project/pull/212307