[PATCH] D72434: Support offset of member designator with the arrow for __builtin_offsetof

[Jim Lin via Phabricator via cfe-commits]

Jim created this revision.
Jim added a reviewer: eli.friedman.
Herald added a project: clang.
Herald added a subscriber: cfe-commits.

Push array index 0 into offsets to support offset of member designator x->b.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D72434

Files:
  clang/lib/Parse/ParseExpr.cpp
  clang/test/Parser/offsetof.c


Index: clang/test/Parser/offsetof.c
===================================================================
--- clang/test/Parser/offsetof.c
+++ clang/test/Parser/offsetof.c
@@ -3,5 +3,3 @@
 struct a { struct { int b; } x[2]; };
 
 int a = __builtin_offsetof(struct a, x; // expected-error{{expected ')'}} expected-note{{to match this '('}}
-// FIXME: This actually shouldn't give an error
-int b = __builtin_offsetof(struct a, x->b); // expected-error{{expected ')'}} expected-note{{to match this '('}}
Index: clang/lib/Parse/ParseExpr.cpp
===================================================================
--- clang/lib/Parse/ParseExpr.cpp
+++ clang/lib/Parse/ParseExpr.cpp
@@ -2165,7 +2165,6 @@
     Comps.back().U.IdentInfo = Tok.getIdentifierInfo();
     Comps.back().LocStart = Comps.back().LocEnd = ConsumeToken();
 
-    // FIXME: This loop leaks the index expressions on error.
     while (1) {
       if (Tok.is(tok::period)) {
         // offsetof-member-designator: offsetof-member-designator '.' identifier
@@ -2200,6 +2199,28 @@
 
         ST.consumeClose();
         Comps.back().LocEnd = ST.getCloseLocation();
+      } else if (Tok.is(tok::arrow)) {
+        // offsetof-member-designator: offsetof-member-design '->' identifier
+        // Push array index 0 into offsets.
+        Comps.push_back(Sema::OffsetOfComponent());
+        Comps.back().isBrackets = true;
+        SourceLocation SavedLoc = ConsumeToken();
+        Comps.back().LocStart = Comps.back().LocEnd = SavedLoc;
+        Res = Actions.ActOnIntegerConstant(SourceLocation(), 0);
+        Comps.back().U.E = Res.get();
+
+        Comps.push_back(Sema::OffsetOfComponent());
+        Comps.back().isBrackets = false;
+        Comps.back().LocStart = SavedLoc;
+
+        if (Tok.isNot(tok::identifier)) {
+          Diag(Tok, diag::err_expected) << tok::identifier;
+          SkipUntil(tok::r_paren, StopAtSemi);
+          return ExprError();
+        }
+        Comps.back().U.IdentInfo = Tok.getIdentifierInfo();
+        Comps.back().LocEnd = ConsumeToken();
+
       } else {
         if (Tok.isNot(tok::r_paren)) {
           PT.consumeClose();


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