[PATCH] D91560: [flang] Duplicate names for ac-implied-do variables erroneously cause errors

[Pete Steinfeld via Phabricator via llvm-commits]

PeteSteinfeld created this revision.
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According to section 19.4, paragraph 5, the scope of an ac-implied-do variable
is the enclosing ac-implied-do.  But we were not creating new scopes upon
entry to an ac-implied-do.  This was causing error messages to be erroneously
emitted.

I fixed, the code, added a test to array-constr-values.f90, and corrected the
test symbol05.f90.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D91560

Files:
  flang/lib/Semantics/resolve-names.cpp
  flang/test/Semantics/array-constr-values.f90
  flang/test/Semantics/symbol05.f90


Index: flang/test/Semantics/symbol05.f90
===================================================================
--- flang/test/Semantics/symbol05.f90
+++ flang/test/Semantics/symbol05.f90
@@ -48,10 +48,10 @@
   !DEF: /s3/Block1/t DerivedType
   type :: t
    !DEF: /s3/Block1/t/x ObjectEntity REAL(4)
-   !DEF: /s3/Block1/t/ImpliedDos1/i (Implicit) ObjectEntity INTEGER(4)
+   !DEF: /s3/Block1/t/ImpliedDos1/ImpliedDos1/i (Implicit) ObjectEntity INTEGER(4)
    real :: x(10) = [(i, i=1,10)]
    !DEF: /s3/Block1/t/y ObjectEntity REAL(4)
-   !DEF: /s3/Block1/t/ImpliedDos2/j ObjectEntity INTEGER(8)
+   !DEF: /s3/Block1/t/ImpliedDos2/ImpliedDos1/j ObjectEntity INTEGER(8)
    real :: y(10) = [(j, j=1,10)]
   end type
  end block
Index: flang/test/Semantics/array-constr-values.f90
===================================================================
--- flang/test/Semantics/array-constr-values.f90
+++ flang/test/Semantics/array-constr-values.f90
@@ -55,9 +55,14 @@
   real, dimension(10), parameter :: good1 = [(99.9, i = 1, 10)]
   real, dimension(100), parameter :: good2 = [((88.8, i = 1, 10), j = 1, 10)]
   !ERROR: Implied DO index is active in surrounding implied DO loop and may not have the same name
-  !ERROR: 'i' is already declared in this scoping unit
   real, dimension(100), parameter :: bad = [((88.8, i = 1, 10), i = 1, 10)]
 
   !ERROR: The stride of an implied DO loop must not be zero
   integer, parameter :: bad2(*) = [(j, j=1,1,0)]
 end subroutine checkC7115
+subroutine checkOkDuplicates
+  real :: realArray(21) = &
+    [ ((1.0, iDuplicate = 1,j), &
+       (0.0, iDuplicate = j,3 ), &
+        j = 1,5 ) ]
+end subroutine
Index: flang/lib/Semantics/resolve-names.cpp
===================================================================
--- flang/lib/Semantics/resolve-names.cpp
+++ flang/lib/Semantics/resolve-names.cpp
@@ -4995,14 +4995,18 @@
   return false;
 }
 
+// Section 19.4, paragraph 5 says that each ac-do-variable has the scope of the
+// enclocing ac-impled-do
 bool ConstructVisitor::Pre(const parser::AcImpliedDo &x) {
   auto &values{std::get<std::list<parser::AcValue>>(x.t)};
   auto &control{std::get<parser::AcImpliedDoControl>(x.t)};
   auto &type{std::get<std::optional<parser::IntegerTypeSpec>>(control.t)};
   auto &bounds{std::get<parser::AcImpliedDoControl::Bounds>(control.t)};
+  PushScope(Scope::Kind::ImpliedDos, nullptr);
   DeclareStatementEntity(bounds.name.thing.thing, type);
   Walk(bounds);
   Walk(values);
+  PopScope();
   return false;
 }
 


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