On 11/29/2012 05:09 PM, Rafael Espindola wrote:
Author: rafael
Date: Thu Nov 29 10:09:03 2012
New Revision: 168895
URL: http://llvm.org/viewvc/llvm-project?rev=168895&view=rev
Log:
Merge function types in C.
After this commit, for the following code
$ cat merge.c
typedef int A;
A f();
typedef int B;
B f();
we obtain the following AST dump, where typedef B gets replaced by A in
the second declaration of f():
$ clang -cc1 -ast-dump merge.c
[...]
(TypedefDecl 0x4e1f220 <merge.c:1:1, col:13> A 'int')
(FunctionDecl 0x4e1f310 <line:2:1, col:5> f 'A ()')
(TypedefDecl 0x4e1f3c0 <line:3:1, col:13> B 'int')
(FunctionDecl 0x4e1f480 <line:4:1, col:5> f 'A ()'))
The chunk responsible for this problem seems to be the following:
Modified: cfe/trunk/lib/Sema/SemaDecl.cpp
URL:
http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaDecl.cpp?rev=168895&r1=168894&r2=168895&view=diff
==============================================================================
--- cfe/trunk/lib/Sema/SemaDecl.cpp (original)
+++ cfe/trunk/lib/Sema/SemaDecl.cpp Thu Nov 29 10:09:03 2012
@@ -2402,6 +2402,12 @@
if (getLangOpts().CPlusPlus)
return MergeCXXFunctionDecl(New, Old, S);
+ // Merge the function types so the we get the composite types for the return
+ // and argument types.
+ QualType Merged = Context.mergeTypes(Old->getType(), New->getType());
+ if (!Merged.isNull())
+ New->setType(Merged);
+
return false;
}
As a bare minimum, I'd suggest to exchange the order of arguments in the
call to mergeTypes():
- QualType Merged = Context.mergeTypes(Old->getType(), New->getType());
+ QualType Merged = Context.mergeTypes(New->getType(), Old->getType());
This will fix (just) the test case above ...
however, in general, what happens to the *syntactic* type after merging?
Is it going to be simply discarded (i.e., replaced by the merged one)?
If so, what about source code fidelity?
Enea.
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