[PATCH] D64991: [analyzer][WIP] Implement a primitive reaching definitions analysis

[Gábor Horváth via Phabricator via cfe-commits]

xazax.hun added inline comments.


================
Comment at: clang/include/clang/Analysis/Analyses/ReachingDefinitions.h:30
+  };
+  const VarDecl *Var;
+  CFGBlock::ConstCFGElementRef E;
----------------
In the future we might also want to reason about `FieldDecl`s.


================
Comment at: clang/include/clang/Analysis/Analyses/ReachingDefinitions.h:50
+  bool operator()(Definition Lhs, Definition Rhs) {
+    return Lhs.Var < Rhs.Var;
+  }
----------------
Is it safe to omit the Kind from the comparisons?


================
Comment at: clang/lib/Analysis/ReachingDefinitions.cpp:61
+    auto AssignmentM =
+        binaryOperator(isAssignmentOperator(),
+                       hasLHS(declRefExpr(to(varDecl().bind("var")))))
----------------
Will this work if the LHS is not directly a declrefexpr?

E.g.:
```
(a, b) = 5;
```
Or more fun cases:
```
(cond ? a : b) = 5;
```


================
Comment at: clang/lib/Analysis/ReachingDefinitions.cpp:102
+    }
+  }
+
----------------
What about the non-const arguments of calls, and indirect writes through pointers? Even if you plan not to handle some of these, I prefer to have a TODO for these the appropriate places as soon as possible.


================
Comment at: clang/lib/Analysis/ReachingDefinitions.cpp:104
+
+  return Ret;
+}
----------------
There are non-assignment operators too, like operator++. You might want to consider them as definitions too.


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  https://reviews.llvm.org/D64991/new/

https://reviews.llvm.org/D64991