Endless operator-> chain causing infinite loop

[Rahul Jain]

Hi,

This is with reference to the below discussion thread:

http://clang-developers.42468.n3.nabble.com/Endless-operator-gt-chain-causing-infinite-loop-td4035258.html

I have tried to implement a command line argument to handle the issue.

The patch for the same is below:

Index: lib/Driver/Tools.cpp
===================================================================
--- lib/Driver/Tools.cpp    (revision 193400)
+++ lib/Driver/Tools.cpp    (working copy)
@@ -2802,6 +2802,12 @@
     CmdArgs.push_back(A->getValue());
   }
 
+  if (Arg *A = Args.getLastArg(options::OPT_foperatorarrow_depth_,
+                               options::OPT_foperatorarrow_depth_EQ)) {
+    CmdArgs.push_back("-foperatorarrow-depth");
+    CmdArgs.push_back(A->getValue());
+  }
+
   if (Arg *A = Args.getLastArg(options::OPT_fconstexpr_depth_EQ)) {
     CmdArgs.push_back("-fconstexpr-depth");
     CmdArgs.push_back(A->getValue());
Index: lib/Frontend/CompilerInvocation.cpp
===================================================================
--- lib/Frontend/CompilerInvocation.cpp    (revision 193400)
+++ lib/Frontend/CompilerInvocation.cpp    (working copy)
@@ -1313,6 +1313,8 @@
   Opts.MathErrno = !Opts.OpenCL && Args.hasArg(OPT_fmath_errno);
   Opts.InstantiationDepth =
       getLastArgIntValue(Args, OPT_ftemplate_depth, 256, Diags);
+  Opts.ArrowDepth = 
+      getLastArgIntValue(Args, OPT_foperatorarrow_depth, 256, Diags);
   Opts.ConstexprCallDepth =
       getLastArgIntValue(Args, OPT_fconstexpr_depth, 512, Diags);
   Opts.ConstexprStepLimit =
Index: lib/Sema/SemaExprCXX.cpp
===================================================================
--- lib/Sema/SemaExprCXX.cpp    (revision 193400)
+++ lib/Sema/SemaExprCXX.cpp    (working copy)
@@ -5188,8 +5188,19 @@
     llvm::SmallPtrSet<CanQualType,8> CTypes;
     SmallVector<SourceLocation, 8> Locations;
     CTypes.insert(Context.getCanonicalType(BaseType));
+      
+    static unsigned int arrow_instantiation_count = 0;
+    while (BaseType->isRecordType()) {
+      arrow_instantiation_count++;
+      if (arrow_instantiation_count >= getLangOpts().ArrowDepth) {
+        Diag(OpLoc,diag::err_arrow_instantiation_depth_exceeded)
+        << getLangOpts().ArrowDepth
+        << Base->getSourceRange();
+        Diag(OpLoc, diag::note_arrow_instantiation_depth)
+        << getLangOpts().ArrowDepth;
+    return ExprError();
+      }
 
-    while (BaseType->isRecordType()) {
       Result = BuildOverloadedArrowExpr(
           S, Base, OpLoc,
           // When in a template specialization and on the first loop iteration,
Index: include/clang/Basic/DiagnosticSemaKinds.td
===================================================================
--- include/clang/Basic/DiagnosticSemaKinds.td    (revision 193400)
+++ include/clang/Basic/DiagnosticSemaKinds.td    (working copy)
@@ -2561,6 +2561,11 @@
 // can handle that case properly.
 def note_ovl_candidate_non_deduced_mismatch_qualified : Note<
     "candidate template ignored: could not match %q0 against %q1">;
+def err_arrow_instantiation_depth_exceeded : Error<
+  "arrow operator instantiation exceeded maximum depth of %0">,
+  DefaultFatal, NoSFINAE;
+def note_arrow_instantiation_depth : Note<
+  "use -foperatorarrow-depth=N to increase arrow operator instantiation depth">;
     
 // Note that we don't treat templates differently for this diagnostic.
 def note_ovl_candidate_arity : Note<"candidate "
Index: include/clang/Basic/LangOptions.def
===================================================================
--- include/clang/Basic/LangOptions.def    (revision 193400)
+++ include/clang/Basic/LangOptions.def    (working copy)
@@ -160,6 +160,8 @@
 ENUM_LANGOPT(SignedOverflowBehavior, SignedOverflowBehaviorTy, 2, SOB_Undefined,
              "signed integer overflow handling")
 
+BENIGN_LANGOPT(ArrowDepth, 32, 256,
+               "maximum arrow instantiation depth")
 BENIGN_LANGOPT(InstantiationDepth, 32, 256,
                "maximum template instantiation depth")
 BENIGN_LANGOPT(ConstexprCallDepth, 32, 512,
Index: include/clang/Driver/CC1Options.td
===================================================================
--- include/clang/Driver/CC1Options.td    (revision 193400)
+++ include/clang/Driver/CC1Options.td    (working copy)
@@ -442,6 +442,8 @@
   HelpText<"Default type visibility">;
 def ftemplate_depth : Separate<["-"], "ftemplate-depth">,
   HelpText<"Maximum depth of recursive template instantiation">;
+def foperatorarrow_depth : Separate<["-"], "foperatorarrow-depth">,
+  HelpText<"Maximum depth of arrow operator instantiation">;
 def fconstexpr_depth : Separate<["-"], "fconstexpr-depth">,
   HelpText<"Maximum depth of recursive constexpr function calls">;
 def fconstexpr_steps : Separate<["-"], "fconstexpr-steps">,
Index: include/clang/Driver/Options.td
===================================================================
--- include/clang/Driver/Options.td    (revision 193400)
+++ include/clang/Driver/Options.td    (working copy)
@@ -775,6 +775,8 @@
 def ftemplate_depth_ : Joined<["-"], "ftemplate-depth-">, Group<f_Group>;
 def ftemplate_backtrace_limit_EQ : Joined<["-"], "ftemplate-backtrace-limit=">,
                                    Group<f_Group>;
+def foperatorarrow_depth_EQ : Joined<["-"], "foperatorarrow-depth=">, Group<f_Group>;
+def foperatorarrow_depth_ : Joined<["-"], "foperatorarrow-depth-">, Group<f_Group>;
 def ftest_coverage : Flag<["-"], "ftest-coverage">, Group<f_Group>;
 def fvectorize : Flag<["-"], "fvectorize">, Group<f_Group>,
   HelpText<"Enable the loop vectorization passes">;



Please if someone could help me by reviewing it and suggesting improvements?

Thanks,
Rahul
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