Don't try to get the layout of an invalid decl in getDeclAlign.

When the decl that we're getting alignment for is a FieldDecl, and the field's
parent record is invalid, skip the actual field alignment calculation (and
return 1-byte alignment in the general case).

Also, assert in in getASTRecordLayout that the decl is valid. This was
inspired by PR16292; see also r184581 and r184751.

llvm-svn: 184883

1 files changed, 20 insertions, 17 deletions

diff --git a/clang/lib/AST/ASTContext.cpp b/clang/lib/AST/ASTContext.cpp
index 91059400761..b5ef5fa2adc 100644
--- a/clang/lib/AST/ASTContext.cpp
+++ b/clang/lib/AST/ASTContext.cpp
@@ -1321,24 +1321,27 @@ CharUnits ASTContext::getDeclAlign(const Decl *D, bool RefAsPointee) const {
     // a max-field-alignment constraint (#pragma pack).  So calculate
     // the actual alignment of the field within the struct, and then
     // (as we're expected to) constrain that by the alignment of the type.
-    if (const FieldDecl *field = dyn_cast<FieldDecl>(VD)) {
-      // So calculate the alignment of the field.
-      const ASTRecordLayout &layout = getASTRecordLayout(field->getParent());
-
-      // Start with the record's overall alignment.
-      unsigned fieldAlign = toBits(layout.getAlignment());
-
-      // Use the GCD of that and the offset within the record.
-      uint64_t offset = layout.getFieldOffset(field->getFieldIndex());
-      if (offset > 0) {
-        // Alignment is always a power of 2, so the GCD will be a power of 2,
-        // which means we get to do this crazy thing instead of Euclid's.
-        uint64_t lowBitOfOffset = offset & (~offset + 1);
-        if (lowBitOfOffset < fieldAlign)
-          fieldAlign = static_cast<unsigned>(lowBitOfOffset);
-      }
+    if (const FieldDecl *Field = dyn_cast<FieldDecl>(VD)) {
+      const RecordDecl *Parent = Field->getParent();
+      // We can only produce a sensible answer if the record is valid.
+      if (!Parent->isInvalidDecl()) {
+        const ASTRecordLayout &Layout = getASTRecordLayout(Parent);
+
+        // Start with the record's overall alignment.
+        unsigned FieldAlign = toBits(Layout.getAlignment());
+
+        // Use the GCD of that and the offset within the record.
+        uint64_t Offset = Layout.getFieldOffset(Field->getFieldIndex());
+        if (Offset > 0) {
+          // Alignment is always a power of 2, so the GCD will be a power of 2,
+          // which means we get to do this crazy thing instead of Euclid's.
+          uint64_t LowBitOfOffset = Offset & (~Offset + 1);
+          if (LowBitOfOffset < FieldAlign)
+            FieldAlign = static_cast<unsigned>(LowBitOfOffset);
+        }
 
-      Align = std::min(Align, fieldAlign);
+        Align = std::min(Align, FieldAlign);
+      }
     }
   }