[Debug] Annotate compiler generated range-for loop variables.

Summary:
This change aims to simplify debugging by annotating the range-for loop artificial variables (range, begin, end) with the scope depth. 


Reviewers: rsmith, dblaikie

Reviewed By: dblaikie

Subscribers: dblaikie, cfe-commits

Tags: #debug-info

Differential Revision: https://reviews.llvm.org/D42813

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@325175 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 8 insertions, 4 deletions

diff --git a/lib/Sema/SemaStmt.cpp b/lib/Sema/SemaStmt.cpp
index 93907038e0..b77018503a 100644
--- a/lib/Sema/SemaStmt.cpp
+++ b/lib/Sema/SemaStmt.cpp
@@ -2025,7 +2025,7 @@ void NoteForRangeBeginEndFunction(Sema &SemaRef, Expr *E,
 
 /// Build a variable declaration for a for-range statement.
 VarDecl *BuildForRangeVarDecl(Sema &SemaRef, SourceLocation Loc,
-                              QualType Type, const char *Name) {
+                              QualType Type, StringRef Name) {
   DeclContext *DC = SemaRef.CurContext;
   IdentifierInfo *II = &SemaRef.PP.getIdentifierTable().get(Name);
   TypeSourceInfo *TInfo = SemaRef.Context.getTrivialTypeSourceInfo(Type, Loc);
@@ -2094,10 +2094,12 @@ StmtResult Sema::ActOnCXXForRangeStmt(Scope *S, SourceLocation ForLoc,
   }
 
   // Build  auto && __range = range-init
+  // Divide by 2, since the variables are in the inner scope (loop body).
+  const auto DepthStr = std::to_string(S->getDepth() / 2);
   SourceLocation RangeLoc = Range->getLocStart();
   VarDecl *RangeVar = BuildForRangeVarDecl(*this, RangeLoc,
                                            Context.getAutoRRefDeductType(),
-                                           "__range");
+                                           std::string("__range") + DepthStr);
   if (FinishForRangeVarDecl(*this, RangeVar, Range, RangeLoc,
                             diag::err_for_range_deduction_failure)) {
     LoopVar->setInvalidDecl();
@@ -2340,10 +2342,12 @@ Sema::BuildCXXForRangeStmt(SourceLocation ForLoc, SourceLocation CoawaitLoc,
       return StmtError();
 
     // Build auto __begin = begin-expr, __end = end-expr.
+    // Divide by 2, since the variables are in the inner scope (loop body).
+    const auto DepthStr = std::to_string(S->getDepth() / 2);
     VarDecl *BeginVar = BuildForRangeVarDecl(*this, ColonLoc, AutoType,
-                                             "__begin");
+                                             std::string("__begin") + DepthStr);
     VarDecl *EndVar = BuildForRangeVarDecl(*this, ColonLoc, AutoType,
-                                           "__end");
+                                           std::string("__end") + DepthStr);
 
     // Build begin-expr and end-expr and attach to __begin and __end variables.
     ExprResult BeginExpr, EndExpr;