[PATCH] D47341: [Sema] Disable creating new delayed typos while correcting existing.

[Volodymyr Sapsai via Phabricator via cfe-commits]

vsapsai updated this revision to Diff 148841.
vsapsai added a comment.

- Fix only infinite loop and don't touch the assertion failure.

New commit message should be:

[Sema] Fix infinite typo correction loop.

NumTypos guard value ~0U doesn't prevent from creating new delayed typos. When
you create new delayed typos during typo correction, value ~0U wraps around to
0. When NumTypos is 0 we can miss some typos and treat an expression as it can
be typo-corrected. But if the expression is still invalid after correction, we
can get stuck in infinite loop trying to correct it.

Fix by not using value ~0U so that NumTypos correctly reflects the number of
typos.

rdar://problem/38642201


https://reviews.llvm.org/D47341

Files:
  clang/lib/Sema/SemaExprCXX.cpp
  clang/test/Sema/typo-correction.c


Index: clang/test/Sema/typo-correction.c
===================================================================
--- clang/test/Sema/typo-correction.c
+++ clang/test/Sema/typo-correction.c
@@ -87,3 +87,16 @@
 void overloadable_callexpr(int arg) {
 	func_overloadable(ar); //expected-error{{use of undeclared identifier}}
 }
+
+// rdar://problem/38642201
+struct rdar38642201 {
+  int fieldName;
+};
+
+void rdar38642201_callee(int x, int y);
+void rdar38642201_caller() {
+  struct rdar38642201 structVar;
+  rdar38642201_callee(
+      structVar1.fieldName1.member1, //expected-error{{use of undeclared identifier 'structVar1'}}
+      structVar2.fieldName2.member2); //expected-error{{use of undeclared identifier 'structVar2'}}
+}
Index: clang/lib/Sema/SemaExprCXX.cpp
===================================================================
--- clang/lib/Sema/SemaExprCXX.cpp
+++ clang/lib/Sema/SemaExprCXX.cpp
@@ -7668,12 +7668,8 @@
   if (E && !ExprEvalContexts.empty() && ExprEvalContexts.back().NumTypos &&
       (E->isTypeDependent() || E->isValueDependent() ||
        E->isInstantiationDependent())) {
-    auto TyposInContext = ExprEvalContexts.back().NumTypos;
-    assert(TyposInContext < ~0U && "Recursive call of CorrectDelayedTyposInExpr");
-    ExprEvalContexts.back().NumTypos = ~0U;
     auto TyposResolved = DelayedTypos.size();
     auto Result = TransformTypos(*this, InitDecl, Filter).Transform(E);
-    ExprEvalContexts.back().NumTypos = TyposInContext;
     TyposResolved -= DelayedTypos.size();
     if (Result.isInvalid() || Result.get() != E) {
       ExprEvalContexts.back().NumTypos -= TyposResolved;


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