[flang] Check definability for logical INQUIRE specifiers (#144797)

check-io.cpp was missing checks for the definability of logical-valued
specifiers in INQUIRE statements (e.g. EXIST=), and therefore also not
noting the definitions of those variables. This could lead to bogus
warnings about undefined function result variables, and also to missed
errors about immutable objects appearing in those specifiers.

Fixes https://github.com/llvm/llvm-project/issues/144453.

flang/lib/Semantics/check-io.cpp

@@ -478,6 +478,8 @@ void IoChecker::Enter(const parser::InquireSpec::LogVar &spec) {
     specKind = IoSpecKind::Pending;
     break;
   }
+  CheckForDefinableVariable(std::get<parser::ScalarLogicalVariable>(spec.t),
+      parser::ToUpperCaseLetters(common::EnumToString(specKind)));
   SetSpecifier(specKind);
 }
 

flang/test/Semantics/bug144453.f90

@@ -0,0 +1,10 @@
+!RUN: %python %S/test_errors.py %s %flang_fc1
+function func(immutable)
+  logical func
+  logical, intent(in) :: immutable
+  !No warning about an undefined function result should appear
+  INQUIRE(file="/usr/local/games/adventure", EXIST=func)
+  !ERROR: EXIST variable 'immutable' is not definable
+  !BECAUSE: 'immutable' is an INTENT(IN) dummy argument
+  INQUIRE(file="/usr/local/games/adventure", EXIST=immutable)
+end