[clang] support `SubstNonTypeTemplateParmExpr`

Summary:
These just point to expressions that we know how to translate.

Fixes #950

Reviewed By: mbouaziz

Differential Revision: D8713784

fbshipit-source-id: 9eafa39

infer/src/clang/cTrans.ml

@@ -3417,10 +3417,11 @@ module CTrans_funct (F : CModule_type.CFrontend) : CModule_type.CTranslation = s
        sub-expressions *)
     | ObjCAvailabilityCheckExpr (_, _, expr_info, _) ->
         undefined_expr trans_state expr_info
+    | SubstNonTypeTemplateParmExpr (_, stmts, _) | SubstNonTypeTemplateParmPackExpr (_, stmts, _) ->
+        let[@warning "-8"] [expr] = stmts in
+        instruction trans_state expr
     (* Infer somehow ended up in templated non instantiated code - right now
        it's not supported and failure in those cases is expected. *)
-    | SubstNonTypeTemplateParmExpr ({Clang_ast_t.si_source_range}, _, _)
-    | SubstNonTypeTemplateParmPackExpr ({Clang_ast_t.si_source_range}, _, _)
     | CXXDependentScopeMemberExpr ({Clang_ast_t.si_source_range}, _, _) ->
         CFrontend_config.unimplemented __POS__ si_source_range
           ~ast_node:(Clang_ast_proj.get_stmt_kind_string instr)

infer/tests/codetoanalyze/cpp/liveness/issues.exp

@@ -17,3 +17,5 @@ codetoanalyze/cpp/liveness/dead_stores.cpp, dead_stores::plus_plus2_bad, 2, DEAD
 codetoanalyze/cpp/liveness/dead_stores.cpp, dead_stores::plus_plus3_bad, 2, DEAD_STORE, no_bucket, ERROR, [Write of unused value]
 codetoanalyze/cpp/liveness/dead_stores.cpp, dead_stores::reassign_param_bad, 0, DEAD_STORE, no_bucket, ERROR, [Write of unused value]
 codetoanalyze/cpp/liveness/dead_stores.cpp, dead_stores::use_then_dead_bad, 3, DEAD_STORE, no_bucket, ERROR, [Write of unused value]
+codetoanalyze/cpp/liveness/non_type_template_param.cpp, X<3>_isZeroBad, 1, DEAD_STORE, no_bucket, ERROR, [Write of unused value]
+codetoanalyze/cpp/liveness/non_type_template_param.cpp, instanciateTemplateBad, 3, DEAD_STORE, no_bucket, ERROR, [Write of unused value]

infer/tests/codetoanalyze/cpp/liveness/non_type_template_param.cpp

@@ -0,0 +1,22 @@
+/*
+ * Copyright (c) 2018-present, Facebook, Inc.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+// see also https://github.com/facebook/infer/issues/950
+
+template <int T>
+struct X {
+  bool isZeroBad() {
+    int unused = 1;
+    return T == 0;
+  }
+};
+
+int instanciateTemplateBad() {
+  X<3> x;
+  x.isZeroBad();
+  int unused = 1;
+  return 0;
+}