address comments

Author: Chen Zheng

llvm/lib/Object/XCOFFObjectFile.cpp

@@ -1288,7 +1288,11 @@ Expected<bool> XCOFFSymbolRef::isFunction() const {
   if (CsectAuxRef.getSymbolType() == XCOFF::XTY_LD)
     return true;
 
-  return createError("csect symbol has no valid symbol type.");
+  return createError(
+      "Symbol csect aux entry with index " +
+      Twine(getObject()->getSymbolIndex(CsectAuxRef.getEntryAddress())) +
+      " has invalid symbol type " +
+      Twine::utohexstr(CsectAuxRef.getSymbolType()));
 }
 
 bool XCOFFSymbolRef::isCsectSymbol() const {

llvm/test/tools/llvm-objdump/XCOFF/aux-entry-invalid-type.test

@@ -0,0 +1,56 @@
+## Check that llvm-objdump --syms reports an error when
+## the symbol type in the csect aux entry of a symbol is not valid.
+
+## Check XCOFF32
+# RUN: yaml2obj --docnum=1 %s -o %t1
+# RUN: not llvm-objdump --syms %t1 2>&1 | FileCheck %s -DOBJ=%t1 --check-prefix=XCOFF32
+
+# XCOFF32: error: '[[OBJ]]': Symbol csect aux entry with index 2 has invalid symbol type 5
+
+--- !XCOFF
+FileHeader:
+  MagicNumber:       0x1DF
+Sections:
+  - Name:                    .text
+    Flags:           [ STYP_TEXT ]
+Symbols:
+  - Name:            .file
+    Section:         N_DEBUG
+    NumberOfAuxEntries: 0
+    Type:            0x0
+    StorageClass:       C_FILE
+  - Name:             test
+    Section:         .text
+    NumberOfAuxEntries: 1
+    StorageClass:       C_EXT
+    AuxEntries:
+      - Type:                   AUX_CSECT
+        SymbolAlignmentAndType: 5
+        StorageMappingClass:    XMC_PR
+
+## Check XCOFF64
+# RUN: yaml2obj --docnum=2 %s -o %t2
+# RUN: not llvm-objdump --syms %t2 2>&1 | FileCheck %s -DOBJ=%t2 --check-prefix=XCOFF64
+
+# XCOFF64: error: '[[OBJ]]': Symbol csect aux entry with index 2 has invalid symbol type 5
+
+--- !XCOFF
+FileHeader:
+  MagicNumber:       0x1F7
+Sections:
+  - Name:                    .text
+    Flags:           [ STYP_TEXT ]
+Symbols:
+  - Name:            .file
+    Section:         N_DEBUG
+    NumberOfAuxEntries: 0
+    Type:            0x0
+    StorageClass:       C_FILE
+  - Name:             test
+    Section:         .text
+    NumberOfAuxEntries: 1
+    StorageClass:       C_EXT
+    AuxEntries:
+      - Type:                   AUX_CSECT
+        SymbolAlignmentAndType: 5
+        StorageMappingClass:    XMC_PR