[clangd] Add more incomplete_type diagnostics that could be fixed by include-fixer.

[kadircet]

Tests seem to be failing on premerge bots:

• https://reviews.llvm.org/harbormaster/unit/view/177841/
• https://reviews.llvm.org/harbormaster/unit/view/177842/

[hokein]

Fix the test.

[hokein]

In D89036#2319320, @kadircet wrote:

Tests seem to be failing on premerge bots:

• https://reviews.llvm.org/harbormaster/unit/view/177841/
• https://reviews.llvm.org/harbormaster/unit/view/177842/

opps, sorry -- I made a few minor changes without rerunning the test, it should be fixed now.

clang-tools-extra/clangd/IncludeFixer.cpp

 
 std::vector<Fix> IncludeFixer::fix(DiagnosticsEngine::Level DiagLevel,
                                    const clang::Diagnostic &Info) const {
   switch (Info.getID()) {
   case diag::err_incomplete_nested_name_spec:
   case diag::err_incomplete_base_class:
   case diag::err_incomplete_member_access:
   case diag::err_incomplete_type:
+  case diag::err_typecheck_decl_incomplete_type:
+  case diag::err_typecheck_incomplete_tag:
+  case diag::err_invalid_incomplete_type_use:
+  case diag::err_sizeof_alignof_incomplete_or_sizeless_type:
+  case diag::err_for_range_incomplete_type:
+  case diag::err_func_def_incomplete_result:
     // Incomplete type diagnostics should have a QualType argument for the
     // incomplete type.
     for (unsigned Idx = 0; Idx < Info.getNumArgs(); ++Idx) {
       if (Info.getArgKind(Idx) == DiagnosticsEngine::ak_qualtype) {
         auto QT = QualType::getFromOpaquePtr((void *)Info.getRawArg(Idx));
         if (const Type *T = QT.getTypePtrOrNull())
           if (T->isIncompleteType())
             return fixIncompleteType(*T);

clang-tools-extra/clangd/unittests/DiagnosticsTests.cpp

TEST(IncludeFixerTest, IncompleteType) {
   Annotations Test(R"cpp(// error-ok
 $insert[[]]namespace ns {
   class X;
   $nested[[X::]]Nested n;
 }
 class Y : $base[[public ns::X]] {};
 int main() {
   ns::X *x;
+  ns::X& ref_x;
   x$access[[->]]f();
   auto& $type[[[]]a] = *x;
+
+  ns::X $incomplete[[var]];
+  $tag[[ref_x]]->f();
+  $use[[ns::X()]];
+  $sizeof[[sizeof]](ns::X);
+  for (auto it : $for[[ref_x]]);
 }
+
+ns::X $return[[func]]() {}
   )cpp");
   auto TU = TestTU::withCode(Test.code());
   TU.ExtraArgs.push_back("-std=c++17");
   auto Index = buildIndexWithSymbol(
       {SymbolWithHeader{"ns::X", "unittest:///x.h", "\"x.h\""}});
   TU.ExternalIndex = Index.get();
 
   EXPECT_THAT(
EXPECT_THAT(
                 DiagName("incomplete_member_access"),
                 WithFix(Fix(Test.range("insert"), "#include \"x.h\"\n",
                             "Add include \"x.h\" for symbol ns::X"))),
           AllOf(
               Diag(Test.range("type"),
                    "incomplete type 'ns::X' where a complete type is required"),
               DiagName("incomplete_type"),
               WithFix(Fix(Test.range("insert"), "#include \"x.h\"\n",
+                          "Add include \"x.h\" for symbol ns::X"))),
+          AllOf(Diag(Test.range("incomplete"),
+                     "variable has incomplete type 'ns::X'"),
+                DiagName("typecheck_decl_incomplete_type"),
+                WithFix(Fix(Test.range("insert"), "#include \"x.h\"\n",
+                            "Add include \"x.h\" for symbol ns::X"))),
+          AllOf(
+              Diag(Test.range("tag"), "incomplete definition of type 'ns::X'"),
+              DiagName("typecheck_incomplete_tag"),
+              WithFix(Fix(Test.range("insert"), "#include \"x.h\"\n",
+                          "Add include \"x.h\" for symbol ns::X"))),
+          AllOf(
+              Diag(Test.range("use"), "invalid use of incomplete type 'ns::X'"),
+              DiagName("invalid_incomplete_type_use"),
+              WithFix(Fix(Test.range("insert"), "#include \"x.h\"\n",
+                          "Add include \"x.h\" for symbol ns::X"))),
+          AllOf(Diag(Test.range("sizeof"), "invalid application of 'sizeof' to "
+                                           "an incomplete type 'ns::X'"),
+                DiagName("sizeof_alignof_incomplete_or_sizeless_type"),
+                WithFix(Fix(Test.range("insert"), "#include \"x.h\"\n",
+                            "Add include \"x.h\" for symbol ns::X"))),
+          AllOf(Diag(Test.range("for"),
+                     "cannot use incomplete type 'ns::X' as a range"),
+                DiagName("for_range_incomplete_type"),
+                WithFix(Fix(Test.range("insert"), "#include \"x.h\"\n",
+                            "Add include \"x.h\" for symbol ns::X"))),
+          AllOf(Diag(Test.range("return"),
+                     "incomplete result type 'ns::X' in function definition"),
+                DiagName("func_def_incomplete_result"),
+                WithFix(Fix(Test.range("insert"), "#include \"x.h\"\n",
                             "Add include \"x.h\" for symbol ns::X")))));
 }
 
 TEST(IncludeFixerTest, NoSuggestIncludeWhenNoDefinitionInHeader) {
   Annotations Test(R"cpp(// error-ok
 $insert[[]]namespace ns {
   class X;
 }
 class Y : $base[[public ns::X]] {};