[clang-tidy] Fix an assert failure in `modernize-loop-convert`.

[hokein]

Summary

The test code will trigger following an assert failure:

assert.h assertion failed at LoopConvertUtils.cpp:560 in
bool clang::tidy::modernize::ForLoopIndexUseVisitor::TraverseMemberExpr(clang::MemberExpr*): ExprType->isPointerType() && "Operator-> returned non-pointer type"

[alexfh]

LG with one nit (see inline comments).

test/clang-tidy/modernize-loop-convert-assert-failure.cpp

3 ↗

(On Diff #48050)

I suppose, this is output of creduce? Can you run creduce again with --sanitize? Thanks!

[hokein]

Minize testcase.

[hokein]

test/clang-tidy/modernize-loop-convert-assert-failure.cpp

4 ↗

(On Diff #48056)

Done with --sanitize. This is the output of creduce.

clang-tools-extra/trunk/clang-tidy/modernize/LoopConvertUtils.cpp

if (Obj && exprReferencesVariable(IndexVar, Obj)) {
     if (!Member->isArrow()) {
       OnlyUsedAsIndex = false;
       return true;
     }
 
     if (ExprType.isNull())
       ExprType = Obj->getType();
 
-    assert(ExprType->isPointerType() && "Operator-> returned non-pointer type");
+    if (!ExprType->isPointerType())
+      return false;
+
     // FIXME: This works around not having the location of the arrow operator.
     // Consider adding OperatorLoc to MemberExpr?
     SourceLocation ArrowLoc = Lexer::getLocForEndOfToken(
         Base->getExprLoc(), 0, Context->getSourceManager(),
         Context->getLangOpts());
     // If something complicated is happening (i.e. the next token isn't an
     // arrow), give up on making this work.
     if (ArrowLoc.isValid()) {

clang-tools-extra/trunk/test/clang-tidy/modernize-loop-convert-assert-failure.cpp

+// RUN: clang-tidy %s -checks=-*,modernize-loop-convert --
+
+// Note: this test expects no assert failure happened in clang-tidy.
+
+class LinguisticItem {
+  LinguisticItem *x0;
+  class x1 {
+    bool operator!= ( const x1 &;
+    operator* ( ;
+    LinguisticItem * &operator-> ( ;
+    operator++ (
+  } begin() const;
+  x1 end() const {
+    LinguisticStream x2;
+    for (x1 x3 = x2.begin x3 != x2.end; ++x3)
+      x3->x0
+  }
+};