Index: flang/docs/Extensions.md
===================================================================
--- flang/docs/Extensions.md
+++ flang/docs/Extensions.md
@@ -283,6 +283,8 @@
 * When a name is brought into a scope by multiple ways,
   such as USE-association as well as an `IMPORT` from its host,
   it's an error only if the resolution is ambiguous.
+* An entity may appear in a `DATA` statement before its explicit
+  type declaration under `IMPLICIT NONE(TYPE)`.
 
 ### Extensions supported when enabled by options
 
Index: flang/include/flang/Common/Fortran-features.h
===================================================================
--- flang/include/flang/Common/Fortran-features.h
+++ flang/include/flang/Common/Fortran-features.h
@@ -36,7 +36,8 @@
     ForwardRefImplicitNone, OpenAccessAppend, BOZAsDefaultInteger,
     DistinguishableSpecifics, DefaultSave, PointerInSeqType, NonCharacterFormat,
     SaveMainProgram, SaveBigMainProgramVariables,
-    DistinctArrayConstructorLengths, PPCVector, RelaxedIntentInChecking)
+    DistinctArrayConstructorLengths, PPCVector, RelaxedIntentInChecking,
+    ForwardRefImplicitNoneData)
 
 // Portability and suspicious usage warnings for conforming code
 ENUM_CLASS(UsageWarning, Portability, PointerToUndefinable,
Index: flang/lib/Semantics/resolve-names.cpp
===================================================================
--- flang/lib/Semantics/resolve-names.cpp
+++ flang/lib/Semantics/resolve-names.cpp
@@ -697,6 +697,7 @@
   bool CheckPossibleBadForwardRef(const Symbol &);
 
   bool inSpecificationPart_{false};
+  bool inDataStmtObject_{false};
   bool inEquivalenceStmt_{false};
 
   // Some information is collected from a specification part for deferred
@@ -2480,6 +2481,9 @@
     // or object, it'll be caught later.
     return;
   }
+  if (inDataStmtObject_) {
+    return;
+  }
   if (!context().HasError(symbol)) {
     Say(symbol.name(), "No explicit type declared for '%s'"_err_en_US);
     context().SetError(symbol);
@@ -2653,7 +2657,7 @@
 }
 
 void ScopeHandler::NotePossibleBadForwardRef(const parser::Name &name) {
-  if (inSpecificationPart_ && name.symbol) {
+  if (inSpecificationPart_ && !inDataStmtObject_ && name.symbol) {
     auto kind{currScope().kind()};
     if ((kind == Scope::Kind::Subprogram && !currScope().IsStmtFunction()) ||
         kind == Scope::Kind::BlockConstruct) {
@@ -6271,6 +6275,12 @@
   }
   auto *prevType{symbol.GetType()};
   if (!prevType) {
+    if (symbol.test(Symbol::Flag::InDataStmt) && isImplicitNoneType() &&
+        context().ShouldWarn(
+            common::LanguageFeature::ForwardRefImplicitNoneData)) {
+      Say(name,
+          "'%s' appeared in a DATA statement before its type was declared under IMPLICIT NONE(TYPE)"_port_en_US);
+    }
     symbol.SetType(type);
   } else if (symbol.has<UseDetails>()) {
     // error recovery case, redeclaration of use-associated name
@@ -6632,6 +6642,7 @@
   auto flagRestorer{common::ScopedSet(inSpecificationPart_, false)};
   common::visit(common::visitors{
                     [&](const Indirection<parser::Variable> &y) {
+                      auto restorer{common::ScopedSet(inDataStmtObject_, true)};
                       Walk(y.value());
                       const parser::Name &first{
                           parser::GetFirstName(y.value())};
@@ -7189,7 +7200,7 @@
     }
     return &name;
   }
-  if (isImplicitNoneType()) {
+  if (isImplicitNoneType() && !inDataStmtObject_) {
     Say(name, "No explicit type declared for '%s'"_err_en_US);
     return nullptr;
   }
Index: flang/test/Semantics/resolve30.f90
===================================================================
--- flang/test/Semantics/resolve30.f90
+++ flang/test/Semantics/resolve30.f90
@@ -1,4 +1,4 @@
-! RUN: %python %S/test_errors.py %s %flang_fc1
+! RUN: %python %S/test_errors.py %s %flang_fc1 -pedantic
 subroutine s1
   integer x
   block
@@ -37,3 +37,10 @@
   !ERROR: Must have INTEGER type, but is REAL(4)
   data(b(j), j=1, 16) / 16 * 0.0 /
 end
+
+subroutine s5
+  implicit none
+  data x/1./
+  !PORTABILITY: 'x' appeared in a DATA statement before its type was declared under IMPLICIT NONE(TYPE)
+  real x
+end