[PATCH] D81101: [flang] Fix crash on erroneous expressions

[Pete Steinfeld via Phabricator via llvm-commits]

PeteSteinfeld created this revision.
PeteSteinfeld added reviewers: klausler, tskeith.
Herald added a reviewer: DavidTruby.
Herald added a project: LLVM.
Herald added a subscriber: llvm-commits.
PeteSteinfeld added a project: Flang.
Herald added a reviewer: jdoerfert.

If you create an expression with parse errors, the `parser::Expr.typedExpr`
will be empty, which causes a compiler crash.  The crash is caused by the
check in check-do-forall.cpp that scans all expresssions to see if `DO`
variables are being modified.  I fixed it by testing to see if `typedExpr`
actually exists before checking to see if it modifies a `DO` variable.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D81101

Files:
  flang/lib/Semantics/check-do-forall.cpp
  flang/test/Semantics/resolve91.f90


Index: flang/test/Semantics/resolve91.f90
===================================================================
--- flang/test/Semantics/resolve91.f90
+++ flang/test/Semantics/resolve91.f90
@@ -44,3 +44,15 @@
     real, dimension(:), pointer :: realArray => localArray
   end type
 end module m4
+
+module m6
+  integer, dimension(3) :: iarray
+  !ERROR: Derived type 'ubound' not found
+  character(len=ubound(iarray)(1)) :: first
+end module m6
+
+module m7
+  integer, dimension(2) :: iarray
+  !ERROR: Derived type 'ubound' not found
+  integer :: ivar = ubound(iarray)(1)
+end module m7
Index: flang/lib/Semantics/check-do-forall.cpp
===================================================================
--- flang/lib/Semantics/check-do-forall.cpp
+++ flang/lib/Semantics/check-do-forall.cpp
@@ -1045,10 +1045,12 @@
 template ActualArgumentSet CollectActualArguments(const SomeExpr &);
 
 void DoForallChecker::Leave(const parser::Expr &parsedExpr) {
-  if (const SomeExpr * expr{GetExpr(parsedExpr)}) {
-    ActualArgumentSet argSet{CollectActualArguments(*expr)};
-    for (const evaluate::ActualArgumentRef &argRef : argSet) {
-      CheckIfArgIsDoVar(*argRef, parsedExpr.source, context_);
+  if (parsedExpr.typedExpr) { // typedExpr is empty on expressions with errors
+    if (const SomeExpr * expr{GetExpr(parsedExpr)}) {
+      ActualArgumentSet argSet{CollectActualArguments(*expr)};
+      for (const evaluate::ActualArgumentRef &argRef : argSet) {
+        CheckIfArgIsDoVar(*argRef, parsedExpr.source, context_);
+      }
     }
   }
 }


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