[clang] Fix CallExpr dependence bit may not respect all its arguments.

Before this patch, the dependence of CallExpr was only computed in the
constructor, the dependence bits might not reflect truth -- some arguments might
be not set (nullptr) during this time, e.g. CXXDefaultArgExpr will be set via
the setArg method in the later parsing stage, so we need to recompute the
dependence bits.

diff --git a/clang/include/clang/AST/Expr.h b/clang/include/clang/AST/Expr.h
index ddef256..0616441 100644 (file)
--- a/clang/include/clang/AST/Expr.h
+++ b/clang/include/clang/AST/Expr.h
@@ -2987,11 +2987,22 @@ public:
   }
 
   /// setArg - Set the specified argument.
+  /// ! the dependence bits might be stale after calling this setter, it is
+  /// *caller*'s responsibility to recompute them by calling
+  /// computeDependence().
   void setArg(unsigned Arg, Expr *ArgExpr) {
     assert(Arg < getNumArgs() && "Arg access out of range!");
     getArgs()[Arg] = ArgExpr;
   }
 
+  /// Compute and set dependence bits.
+  void computeDependence() {
+    setDependence(clang::computeDependence(
+        this, llvm::makeArrayRef(
+                  reinterpret_cast<Expr **>(getTrailingStmts() + PREARGS_START),
+                  getNumPreArgs())));
+  }
+
   /// Reduce the number of arguments in this call expression. This is used for
   /// example during error recovery to drop extra arguments. There is no way
   /// to perform the opposite because: 1.) We don't track how much storage

diff --git a/clang/lib/AST/Expr.cpp b/clang/lib/AST/Expr.cpp
index 613abb7..03dc65e 100644 (file)
--- a/clang/lib/AST/Expr.cpp
+++ b/clang/lib/AST/Expr.cpp
@@ -1398,7 +1398,7 @@ CallExpr::CallExpr(StmtClass SC, Expr *Fn, ArrayRef<Expr *> PreArgs,
   for (unsigned I = Args.size(); I != NumArgs; ++I)
     setArg(I, nullptr);
 
-  setDependence(computeDependence(this, PreArgs));
+  this->computeDependence();
 
   CallExprBits.HasFPFeatures = FPFeatures.requiresTrailingStorage();
   if (hasStoredFPFeatures())

diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp
index 3df74b5..a3a26d2 100644 (file)
--- a/clang/lib/Sema/SemaExpr.cpp
+++ b/clang/lib/Sema/SemaExpr.cpp
@@ -5928,6 +5928,7 @@ Sema::ConvertArgumentsForCall(CallExpr *Call, Expr *Fn,
   for (unsigned i = 0; i < TotalNumArgs; ++i)
     Call->setArg(i, AllArgs[i]);
 
+  Call->computeDependence();
   return false;
 }
 
@@ -6863,6 +6864,7 @@ ExprResult Sema::BuildResolvedCallExpr(Expr *Fn, NamedDecl *NDecl,
 
       TheCall->setArg(i, Arg);
     }
+    TheCall->computeDependence();
   }
 
   if (CXXMethodDecl *Method = dyn_cast_or_null<CXXMethodDecl>(FDecl))

diff --git a/clang/test/SemaCXX/recovery-expr-type.cpp b/clang/test/SemaCXX/recovery-expr-type.cpp
index d3ac772..509cd17 100644 (file)
--- a/clang/test/SemaCXX/recovery-expr-type.cpp
+++ b/clang/test/SemaCXX/recovery-expr-type.cpp
@@ -139,6 +139,7 @@ void baz() {
 
 namespace test12 {
 // Verify we do not crash.
-void fun(int *foo = no_such_function()); // expected-error {{undeclared identifier}}
-void baz() { fun(); }
+int fun(int *foo = no_such_function()); // expected-error {{undeclared identifier}}
+void crash1() { fun(); }
+void crash2() { constexpr int s = fun(); }
 } // namespace test12