From 8123b6e7838216a53ba050f07e36fee28e1bbdaf Mon Sep 17 00:00:00 2001
From: Sam Panzer <espanz@gmail.com>
Date: Thu, 6 Sep 2012 21:50:08 +0000
Subject: [PATCH] Clarified diagnostics for range-based for loops with invalid
 ranges

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@163350 91177308-0d34-0410-b5e6-96231b3b80d8
---
 include/clang/Basic/DiagnosticSemaKinds.td    |  2 ++
 lib/Sema/SemaStmt.cpp                         |  6 ++++++
 .../stmt.stmt/stmt.iter/stmt.ranged/p1.cpp    | 19 ++++++++++++++++---
 3 files changed, 24 insertions(+), 3 deletions(-)

diff --git a/include/clang/Basic/DiagnosticSemaKinds.td b/include/clang/Basic/DiagnosticSemaKinds.td
index b10e8cb008..75c98b1159 100644
--- a/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/include/clang/Basic/DiagnosticSemaKinds.td
@@ -1430,6 +1430,8 @@ def err_for_range_invalid: Error<
 def err_for_range_dereference : Error<
   "invalid range expression of type %0; did you mean to dereference it "
   "with '*'?">;
+def note_for_range_invalid_iterator : Note <
+  "in implicit call to 'operator%select{!=|*|++}0' for iterator of type %1">;
 def note_for_range_begin_end : Note<
   "selected '%select{begin|end}0' %select{function|template }1%2 with iterator type %3">;
 
diff --git a/lib/Sema/SemaStmt.cpp b/lib/Sema/SemaStmt.cpp
index 76410e20ac..17d1de81e7 100644
--- a/lib/Sema/SemaStmt.cpp
+++ b/lib/Sema/SemaStmt.cpp
@@ -1966,6 +1966,8 @@ Sema::BuildCXXForRangeStmt(SourceLocation ForLoc, SourceLocation ColonLoc,
     NotEqExpr = ActOnBooleanCondition(S, ColonLoc, NotEqExpr.get());
     NotEqExpr = ActOnFinishFullExpr(NotEqExpr.get());
     if (NotEqExpr.isInvalid()) {
+      Diag(RangeLoc, diag::note_for_range_invalid_iterator)
+        << RangeLoc << 0 << BeginRangeRef.get()->getType();
       NoteForRangeBeginEndFunction(*this, BeginExpr.get(), BEF_begin);
       if (!Context.hasSameType(BeginType, EndType))
         NoteForRangeBeginEndFunction(*this, EndExpr.get(), BEF_end);
@@ -1981,6 +1983,8 @@ Sema::BuildCXXForRangeStmt(SourceLocation ForLoc, SourceLocation ColonLoc,
     IncrExpr = ActOnUnaryOp(S, ColonLoc, tok::plusplus, BeginRef.get());
     IncrExpr = ActOnFinishFullExpr(IncrExpr.get());
     if (IncrExpr.isInvalid()) {
+      Diag(RangeLoc, diag::note_for_range_invalid_iterator)
+        << RangeLoc << 2 << BeginRangeRef.get()->getType() ;
       NoteForRangeBeginEndFunction(*this, BeginExpr.get(), BEF_begin);
       return StmtError();
     }
@@ -1993,6 +1997,8 @@ Sema::BuildCXXForRangeStmt(SourceLocation ForLoc, SourceLocation ColonLoc,
 
     ExprResult DerefExpr = ActOnUnaryOp(S, ColonLoc, tok::star, BeginRef.get());
     if (DerefExpr.isInvalid()) {
+      Diag(RangeLoc, diag::note_for_range_invalid_iterator)
+        << RangeLoc << 1 << BeginRangeRef.get()->getType();
       NoteForRangeBeginEndFunction(*this, BeginExpr.get(), BEF_begin);
       return StmtError();
     }
diff --git a/test/CXX/stmt.stmt/stmt.iter/stmt.ranged/p1.cpp b/test/CXX/stmt.stmt/stmt.iter/stmt.ranged/p1.cpp
index 66e30f5dc6..6c6fe09165 100644
--- a/test/CXX/stmt.stmt/stmt.iter/stmt.ranged/p1.cpp
+++ b/test/CXX/stmt.stmt/stmt.iter/stmt.ranged/p1.cpp
@@ -129,14 +129,15 @@ void g() {
   };
   for (auto u : NoBegin()) { // expected-error {{range type 'NoBegin' has 'end' member but no 'begin' member}}
   }
-  for (auto u : NoEnd()) { // expected-error {{range type 'NoEnd' has 'begin' member but no 'end' member}}
+  for (auto u : NoEnd()) { // expected-error {{range type 'NoEnd' has 'begin' member but no 'end' member}} 
   }
 
   struct NoIncr {
     void *begin(); // expected-note {{selected 'begin' function with iterator type 'void *'}}
     void *end();
   };
-  for (auto u : NoIncr()) { // expected-error {{arithmetic on a pointer to void}}
+  for (auto u : NoIncr()) { // expected-error {{arithmetic on a pointer to void}}\
+    expected-note {{in implicit call to 'operator++' for iterator of type 'NoIncr'}}
   }
 
   struct NoNotEq {
@@ -144,7 +145,19 @@ void g() {
     NoNotEq end();
     void operator++();
   };
-  for (auto u : NoNotEq()) { // expected-error {{invalid operands to binary expression}}
+  for (auto u : NoNotEq()) { // expected-error {{invalid operands to binary expression}}\
+    expected-note {{in implicit call to 'operator!=' for iterator of type 'NoNotEq'}}
+  }
+
+  struct NoDeref {
+    NoDeref begin(); // expected-note {{selected 'begin' function}}
+    NoDeref end();
+    void operator++();
+    bool operator!=(NoDeref &);
+  };
+
+  for (auto u : NoDeref()) { // expected-error {{indirection requires pointer operand}} \
+    expected-note {{in implicit call to 'operator*' for iterator of type 'NoDeref'}}
   }
 
   struct NoCopy {
-- 
2.40.0