[flang-commits] [flang] 3061334 - [flang] Don't crash on some bogus expressions

[peter klausler via flang-commits]

Author: peter klausler
Date: 2021-06-16T12:26:39-07:00
New Revision: 3061334e0d887b260b023ca5613359a84b7da8e7

URL: https://github.com/llvm/llvm-project/commit/3061334e0d887b260b023ca5613359a84b7da8e7
DIFF: https://github.com/llvm/llvm-project/commit/3061334e0d887b260b023ca5613359a84b7da8e7.diff

LOG: [flang] Don't crash on some bogus expressions

Recover more gracefully from user errors in expressions.

Differential Revision: https://reviews.llvm.org/D104326

Added: 
    

Modified: 
    flang/lib/Semantics/expression.cpp
    flang/lib/Semantics/resolve-names.cpp
    flang/test/Semantics/select-rank.f90

Removed: 
    


################################################################################
diff  --git a/flang/lib/Semantics/expression.cpp b/flang/lib/Semantics/expression.cpp
index 62cb0f1b87f3e..2b3f6fb57d633 100644
--- a/flang/lib/Semantics/expression.cpp
+++ b/flang/lib/Semantics/expression.cpp
@@ -174,7 +174,8 @@ class ArgumentAnalyzer {
 // Wraps a data reference in a typed Designator<>, and a procedure
 // or procedure pointer reference in a ProcedureDesignator.
 MaybeExpr ExpressionAnalyzer::Designate(DataRef &&ref) {
-  const Symbol &symbol{ref.GetLastSymbol().GetUltimate()};
+  const Symbol &last{ref.GetLastSymbol()};
+  const Symbol &symbol{last.GetUltimate()};
   if (semantics::IsProcedure(symbol)) {
     if (auto *component{std::get_if<Component>(&ref.u)}) {
       return Expr<SomeType>{ProcedureDesignator{std::move(*component)}};
@@ -193,8 +194,17 @@ MaybeExpr ExpressionAnalyzer::Designate(DataRef &&ref) {
           symbol.name());
     }
     return std::nullopt;
+  } else if (MaybeExpr result{AsGenericExpr(std::move(ref))}) {
+    return result;
   } else {
-    return AsGenericExpr(std::move(ref));
+    if (!context_.HasError(last) && !context_.HasError(symbol)) {
+      AttachDeclaration(
+          Say("'%s' is not an object that can appear in an expression"_err_en_US,
+              last.name()),
+          symbol);
+      context_.SetError(last);
+    }
+    return std::nullopt;
   }
 }
 

diff  --git a/flang/lib/Semantics/resolve-names.cpp b/flang/lib/Semantics/resolve-names.cpp
index e01b796366fda..110114597d1fd 100644
--- a/flang/lib/Semantics/resolve-names.cpp
+++ b/flang/lib/Semantics/resolve-names.cpp
@@ -3361,7 +3361,8 @@ void DeclarationVisitor::EndDecl() {
 }
 
 bool DeclarationVisitor::CheckUseError(const parser::Name &name) {
-  const auto *details{name.symbol->detailsIf<UseErrorDetails>()};
+  const auto *details{
+      name.symbol ? name.symbol->detailsIf<UseErrorDetails>() : nullptr};
   if (!details) {
     return false;
   }
@@ -3370,6 +3371,7 @@ bool DeclarationVisitor::CheckUseError(const parser::Name &name) {
     msg.Attach(location, "'%s' was use-associated from module '%s'"_en_US,
         name.source, module->GetName().value());
   }
+  context().SetError(*name.symbol);
   return true;
 }
 
@@ -5247,6 +5249,7 @@ void ConstructVisitor::ResolveIndexName(
         !prevRoot.has<EntityDetails>()) {
       Say2(name, "Index name '%s' conflicts with existing identifier"_err_en_US,
           *prev, "Previous declaration of '%s'"_en_US);
+      context().SetError(symbol);
       return;
     } else {
       if (const auto *type{prevRoot.GetType()}) {

diff  --git a/flang/test/Semantics/select-rank.f90 b/flang/test/Semantics/select-rank.f90
index e8571b81762c1..60582876e5ab5 100644
--- a/flang/test/Semantics/select-rank.f90
+++ b/flang/test/Semantics/select-rank.f90
@@ -220,9 +220,11 @@ subroutine CALL_ME10(x)
     SELECT RANK(ptr=>x)
     RANK (3)
       PRINT *, "PRINT RANK 3"
+      !ERROR: 'ptr' is not an object that can appear in an expression
       j = INT(0, KIND=MERGE(KIND(0), -1, RANK(ptr) == 0))
     RANK (1)
       PRINT *, "PRINT RANK 1"
+      !ERROR: 'ptr' is not an object that can appear in an expression
       j = INT(0, KIND=MERGE(KIND(0), -1, RANK(ptr) == 1))
     END SELECT
    end subroutine