[clang] Fix a crash on CheckArgAlignment.

We might encounter an undeduced type before calling getTypeAlignInChars.

NOTE: this retrieves the fix from
8f80c66, which was removed in Adam's
followup fix fbfcfdb. We originally
thought the crash was caused by recovery-ast, but it turns out it can
occur for other cases, e.g. typo-correction.

Differential Revision: https://reviews.llvm.org/D102750

Author: hokein

clang/lib/Sema/SemaChecking.cpp

@@ -4571,7 +4571,8 @@ void Sema::CheckArgAlignment(SourceLocation Loc, NamedDecl *FDecl,
 
   // Find expected alignment, and the actual alignment of the passed object.
   // getTypeAlignInChars requires complete types
-  if (ParamTy->isIncompleteType() || ArgTy->isIncompleteType())
+  if (ParamTy->isIncompleteType() || ArgTy->isIncompleteType() ||
+      ParamTy->isUndeducedType() || ArgTy->isUndeducedType())
     return;
 
   CharUnits ParamAlign = Context.getTypeAlignInChars(ParamTy);

clang/test/SemaCXX/typo-correction-crash.cpp

@@ -42,3 +42,12 @@ class S {
   }
 };
 }
+
+namespace NoCrashOnCheckArgAlignment {
+template <typename a> void b(a &);
+void test() {
+  for (auto file_data :b(files_db_data)); // expected-error {{use of undeclared identifier 'files_db_data'; did you mean 'file_data'?}} \
+                                          // expected-note {{'file_data' declared here}} \
+                                          // expected-error {{cannot use type 'void' as a range}}
+}
+}