[Diagnostics] Improve -Wsizeof-pointer-div

Emit diag note with a location of pointer declaration.
Revisited/added tests.

llvm-svn: 369206

3 files changed, 26 insertions, 10 deletions

diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td b/clang/include/clang/Basic/DiagnosticSemaKinds.td
index 2abb43c4584..0522f2a2ed2 100644
--- a/clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -3346,6 +3346,8 @@ def warn_address_of_reference_null_compare : Warning<
   InGroup<TautologicalUndefinedCompare>;
 def note_reference_is_return_value : Note<"%0 returns a reference">;
 
+def note_pointer_declared_here : Note<
+  "pointer %0 declared here">;
 def warn_division_sizeof_ptr : Warning<
   "'%0' will return the size of the pointer, not the array itself">,
   InGroup<DiagGroup<"sizeof-pointer-div">>;
diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp
index de06cc8363f..b218ad1f66c 100644
--- a/clang/lib/Sema/SemaExpr.cpp
+++ b/clang/lib/Sema/SemaExpr.cpp
@@ -9075,7 +9075,8 @@ static void DiagnoseDivisionSizeofPointer(Sema &S, Expr *LHS, Expr *RHS,
       RUE->getKind() != UETT_SizeOf)
     return;
 
-  QualType LHSTy = LUE->getArgumentExpr()->IgnoreParens()->getType();
+  const Expr *LHSArg = LUE->getArgumentExpr()->IgnoreParens();
+  QualType LHSTy = LHSArg->getType();
   QualType RHSTy;
 
   if (RUE->isArgumentType())
@@ -9085,10 +9086,15 @@ static void DiagnoseDivisionSizeofPointer(Sema &S, Expr *LHS, Expr *RHS,
 
   if (!LHSTy->isPointerType() || RHSTy->isPointerType())
     return;
-  if (LHSTy->getPointeeType() != RHSTy)
+  if (LHSTy->getPointeeType().getCanonicalType() != RHSTy.getCanonicalType())
     return;
 
   S.Diag(Loc, diag::warn_division_sizeof_ptr) << LHS << LHS->getSourceRange();
+  if (const auto *DRE = dyn_cast<DeclRefExpr>(LHSArg)) {
+    if (const ValueDecl *LHSArgDecl = DRE->getDecl())
+      S.Diag(LHSArgDecl->getLocation(), diag::note_pointer_declared_here)
+          << LHSArgDecl;
+  }
 }
 
 static void DiagnoseBadDivideOrRemainderValues(Sema& S, ExprResult &LHS,
diff --git a/clang/test/Sema/div-sizeof-ptr.cpp b/clang/test/Sema/div-sizeof-ptr.cpp
index 4a411ff6bb0..835c858e592 100644
--- a/clang/test/Sema/div-sizeof-ptr.cpp
+++ b/clang/test/Sema/div-sizeof-ptr.cpp
@@ -5,12 +5,20 @@ int f(Ty (&Array)[N]) {
   return sizeof(Array) / sizeof(Ty); // Should not warn
 }
 
-void test(int *p, int **q) {
+typedef int int32;
+
+void test(int *p, int **q) {         // expected-note 5 {{pointer 'p' declared here}}
   int a1 = sizeof(p) / sizeof(*p);   // expected-warning {{'sizeof (p)' will return the size of the pointer, not the array itself}}
   int a2 = sizeof p / sizeof *p;     // expected-warning {{'sizeof p' will return the size of the pointer, not the array itself}}
-  int a3 = sizeof(*q) / sizeof(**q); // expected-warning {{'sizeof (*q)' will return the size of the pointer, not the array itself}}
-  int a4 = sizeof(p) / sizeof(int);  // expected-warning {{'sizeof (p)' will return the size of the pointer, not the array itself}}
-  int a5 = sizeof(p) / sizeof(p[0]); // expected-warning {{'sizeof (p)' will return the size of the pointer, not the array itself}}
+  int a3 = sizeof(p) / sizeof(int);  // expected-warning {{'sizeof (p)' will return the size of the pointer, not the array itself}}
+  int a4 = sizeof(p) / sizeof(p[0]); // expected-warning {{'sizeof (p)' will return the size of the pointer, not the array itself}}
+  int a5 = sizeof(p) / sizeof(int32); // expected-warning {{'sizeof (p)' will return the size of the pointer, not the array itself}}
+
+  int32 *d;                           // expected-note 2 {{pointer 'd' declared here}}
+  int a6 = sizeof(d) / sizeof(int32); // expected-warning {{'sizeof (d)' will return the size of the pointer, not the array itself}}
+  int a7 = sizeof(d) / sizeof(int);  // expected-warning {{'sizeof (d)' will return the size of the pointer, not the array itself}}
+
+  int a8 = sizeof(*q) / sizeof(**q); // expected-warning {{'sizeof (*q)' will return the size of the pointer, not the array itself}}
 
   // Should not warn
   int b1 = sizeof(int *) / sizeof(int);
@@ -19,10 +27,10 @@ void test(int *p, int **q) {
   int b4 = sizeof(p) / sizeof(char);
 
   int arr[10];
-  int b5 = sizeof(arr) / sizeof(*arr);
-  int b6 = sizeof(arr) / sizeof(arr[0]);
-  int b7 = sizeof(arr) / sizeof(int);
+  int c1 = sizeof(arr) / sizeof(*arr);
+  int c2 = sizeof(arr) / sizeof(arr[0]);
+  int c3 = sizeof(arr) / sizeof(int);
 
   int arr2[10][12];
-  int b8 = sizeof(arr2) / sizeof(*arr2);
+  int d1 = sizeof(arr2) / sizeof(*arr2);
 }