[clang][dataflow] Don't crash when caller args are missing storage locations

This patch modifies `Environment`'s `pushCall` method to pass over arguments that are missing storage locations, instead of crashing.

Reviewed By: gribozavr2

Differential Revision: https://reviews.llvm.org/D131600

clang/include/clang/Analysis/FlowSensitive/DataflowEnvironment.h

@@ -140,8 +140,6 @@ public:
   ///  The body of the callee must not reference globals.
   ///
   ///  The arguments of `Call` must map 1:1 to the callee's parameters.
-  ///
-  ///  Each argument of `Call` must already have a `StorageLocation`.
   Environment pushCall(const CallExpr *Call) const;
   Environment pushCall(const CXXConstructExpr *Call) const;
 

clang/lib/Analysis/FlowSensitive/DataflowEnvironment.cpp

@@ -253,7 +253,8 @@ void Environment::pushCallInternal(const FunctionDecl *FuncDecl,
 
     const Expr *Arg = Args[ArgIndex];
     auto *ArgLoc = getStorageLocation(*Arg, SkipPast::Reference);
-    assert(ArgLoc != nullptr);
+    if (ArgLoc == nullptr)
+      continue;
 
     const VarDecl *Param = *ParamIt;
     auto &Loc = createStorageLocation(*Param);

clang/unittests/Analysis/FlowSensitive/TransferTest.cpp

@@ -4229,6 +4229,27 @@ TEST(TransferTest, ContextSensitiveReturnArg) {
                /*.BuiltinTransferOptions=*/{/*.ContextSensitive=*/true}});
 }
 
+TEST(TransferTest, ContextSensitiveReturnInt) {
+  std::string Code = R"(
+    int identity(int x) { return x; }
+
+    void target() {
+      int y = identity(42);
+      // [[p]]
+    }
+  )";
+  runDataflow(Code,
+              [](llvm::ArrayRef<
+                     std::pair<std::string, DataflowAnalysisState<NoopLattice>>>
+                     Results,
+                 ASTContext &ASTCtx) {
+                ASSERT_THAT(Results, ElementsAre(Pair("p", _)));
+                // This just tests that the analysis doesn't crash.
+              },
+              {/*.ApplyBuiltinTransfer=*/true,
+               /*.BuiltinTransferOptions=*/{/*.ContextSensitive=*/true}});
+}
+
 TEST(TransferTest, ContextSensitiveMethodLiteral) {
   std::string Code = R"(
     class MyClass {