[PATCH] D59776: [Sema] Don't check for array bounds when the types in the base expression are dependent.

[Bruno Ricci via Phabricator via cfe-commits]

riccibruno created this revision.
riccibruno added reviewers: efriedma, aaron.ballman.
riccibruno added a project: clang.
Herald added a subscriber: cfe-commits.

Bail-out of `CheckArrayAccess` when the types of the base expression before and 
after eventual casts are dependent. We will get another chance to check for 
array bounds during instantiation. Fixes PR41087.


Repository:
  rC Clang

https://reviews.llvm.org/D59776

Files:
  lib/Sema/SemaChecking.cpp
  test/SemaCXX/array-bounds.cpp


Index: test/SemaCXX/array-bounds.cpp
===================================================================
--- test/SemaCXX/array-bounds.cpp
+++ test/SemaCXX/array-bounds.cpp
@@ -296,3 +296,16 @@
   // We can still diagnose this.
   C &h() { return reinterpret_cast<C *>(xxx)[-1]; } // expected-warning 
{{array index -1 is before the beginning of the array}}
 }
+
+namespace PR41087 {
+  template <typename Ty> void foo() {
+    Ty buffer[2]; // expected-note 3{{array 'buffer' declared here}}
+    ((char *)buffer)[2] = 'A'; // expected-warning 1{{array index 2 is past 
the end of the array (which contains 2 elements)}}
+    ((char *)buffer)[-1] = 'A'; // expected-warning 2{{array index -1 is 
before the beginning of the array}}
+  }
+
+  void f() {
+    foo<char>(); // expected-note 1{{in instantiation of function template 
specialization}}
+    foo<int>(); // expected-note 1{{in instantiation of function template 
specialization}}
+  };
+}
Index: lib/Sema/SemaChecking.cpp
===================================================================
--- lib/Sema/SemaChecking.cpp
+++ lib/Sema/SemaChecking.cpp
@@ -12949,6 +12949,8 @@
     return;
 
   const Type *BaseType = ArrayTy->getElementType().getTypePtr();
+  if (EffectiveType->isDependentType() || BaseType->isDependentType())
+    return;
 
   Expr::EvalResult Result;
   if (!IndexExpr->EvaluateAsInt(Result, Context, Expr::SE_AllowSideEffects))



Index: test/SemaCXX/array-bounds.cpp
===================================================================
--- test/SemaCXX/array-bounds.cpp
+++ test/SemaCXX/array-bounds.cpp
@@ -296,3 +296,16 @@
   // We can still diagnose this.
   C &h() { return reinterpret_cast<C *>(xxx)[-1]; } // expected-warning {{array index -1 is before the beginning of the array}}
 }
+
+namespace PR41087 {
+  template <typename Ty> void foo() {
+    Ty buffer[2]; // expected-note 3{{array 'buffer' declared here}}
+    ((char *)buffer)[2] = 'A'; // expected-warning 1{{array index 2 is past the end of the array (which contains 2 elements)}}
+    ((char *)buffer)[-1] = 'A'; // expected-warning 2{{array index -1 is before the beginning of the array}}
+  }
+
+  void f() {
+    foo<char>(); // expected-note 1{{in instantiation of function template specialization}}
+    foo<int>(); // expected-note 1{{in instantiation of function template specialization}}
+  };
+}
Index: lib/Sema/SemaChecking.cpp
===================================================================
--- lib/Sema/SemaChecking.cpp
+++ lib/Sema/SemaChecking.cpp
@@ -12949,6 +12949,8 @@
     return;
 
   const Type *BaseType = ArrayTy->getElementType().getTypePtr();
+  if (EffectiveType->isDependentType() || BaseType->isDependentType())
+    return;
 
   Expr::EvalResult Result;
   if (!IndexExpr->EvaluateAsInt(Result, Context, Expr::SE_AllowSideEffects))

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