[PATCH] D130303: Handle template parameter-dependent bit field widths in libclang

[Collin Baker via Phabricator via cfe-commits]

collinbaker created this revision.
collinbaker added a reviewer: rnk.
Herald added a subscriber: arphaman.
Herald added a project: All.
collinbaker requested review of this revision.
Herald added a project: clang.
Herald added a subscriber: cfe-commits.

In a class template, a bit field's width may depend on a template
parameter. In this case the width expression cannot be evaluated.

Previously clang_getFieldDeclBitWidth() would assert, or cause memory
unsafety and return an invalid result if assertions are disabled.

This adds a check for this case which returns an error code. An
additional function clang_isFieldDeclBitWidthDependent() as added for
users to check for this case.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D130303

Files:
  clang/include/clang-c/Index.h
  clang/tools/libclang/CXType.cpp


Index: clang/tools/libclang/CXType.cpp
===================================================================
--- clang/tools/libclang/CXType.cpp
+++ clang/tools/libclang/CXType.cpp
@@ -15,6 +15,7 @@
 #include "CXString.h"
 #include "CXTranslationUnit.h"
 #include "CXType.h"
+#include "clang-c/Index.h"
 #include "clang/AST/Decl.h"
 #include "clang/AST/DeclObjC.h"
 #include "clang/AST/DeclTemplate.h"
@@ -377,6 +378,21 @@
   return ULLONG_MAX;
 }
 
+unsigned clang_isFieldDeclBitWidthDependent(CXCursor C) {
+  using namespace cxcursor;
+
+  if (clang_isDeclaration(C.kind)) {
+    const Decl *D = getCursorDecl(C);
+
+    if (const FieldDecl *FD = dyn_cast_or_null<FieldDecl>(D)) {
+      if (FD->isBitField() && FD->getBitWidth()->isValueDependent())
+        return 1;
+    }
+  }
+
+  return 0;
+}
+
 int clang_getFieldDeclBitWidth(CXCursor C) {
   using namespace cxcursor;
 
@@ -384,7 +400,7 @@
     const Decl *D = getCursorDecl(C);
 
     if (const FieldDecl *FD = dyn_cast_or_null<FieldDecl>(D)) {
-      if (FD->isBitField())
+      if (FD->isBitField() && !FD->getBitWidth()->isValueDependent())
         return FD->getBitWidthValue(getCursorContext(C));
     }
   }
Index: clang/include/clang-c/Index.h
===================================================================
--- clang/include/clang-c/Index.h
+++ clang/include/clang-c/Index.h
@@ -3545,10 +3545,19 @@
 CINDEX_LINKAGE unsigned long long
 clang_getEnumConstantDeclUnsignedValue(CXCursor C);
 
+/**
+ * Returns non-zero if a bit field's width depends on template parameters.
+ *
+ * If the cursor does not reference a bit field declaration or if the bit
+ * field's width does not depend on template parameters, 0 is returned.
+ */
+CINDEX_LINKAGE unsigned clang_isFieldDeclBitWidthDependent(CXCursor C);
+
 /**
  * Retrieve the bit width of a bit field declaration as an integer.
  *
- * If a cursor that is not a bit field declaration is passed in, -1 is returned.
+ * If a cursor that is not a bit field declaration is passed in, or if the bit
+ * field's width expression cannot be evaluated, -1 is returned.
  */
 CINDEX_LINKAGE int clang_getFieldDeclBitWidth(CXCursor C);
 


-------------- next part --------------
A non-text attachment was scrubbed...
Name: D130303.446631.patch
Type: text/x-patch
Size: 2150 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/cfe-commits/attachments/20220721/6c2822ed/attachment.bin>