[PATCH] D27478: Make ASTContext::getDeclAlign return the correct alignment for FunctionDecls

[Akira Hatanaka via Phabricator via cfe-commits]

ahatanak created this revision.
ahatanak added reviewers: rsmith, doug.gregor.
ahatanak added a subscriber: cfe-commits.

This patch silences an incorrect warning that is issued when a function pointer is cast to another function pointer type. The warning gets issued because alignments of the source and destination do not match in Sema::CheckCastAlign, which happens because ASTContext::getTypeInfoImpl and ASTContext::getDeclAlign return different values for functions (the former returns 4 while the latter returns 1).


https://reviews.llvm.org/D27478

Files:
  lib/AST/ASTContext.cpp
  test/Sema/warn-cast-align.c


Index: test/Sema/warn-cast-align.c
===================================================================
--- test/Sema/warn-cast-align.c
+++ test/Sema/warn-cast-align.c
@@ -59,3 +59,11 @@
   i = (int *)&s.s0;
   i = (int *)a;
 }
+
+// No warnings.
+typedef int (*FnTy)(void);
+unsigned int func5(void);
+
+FnTy test5(void) {
+  return (FnTy)&func5;
+}
Index: lib/AST/ASTContext.cpp
===================================================================
--- lib/AST/ASTContext.cpp
+++ lib/AST/ASTContext.cpp
@@ -1501,7 +1501,9 @@
 
         Align = std::min(Align, FieldAlign);
       }
-    }
+    } else if (isa<FunctionDecl>(VD))
+      // GCC extension: alignment of functions is 32 bits
+      Align = 32;
   }
 
   return toCharUnitsFromBits(Align);


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