From 9afbd500cf6a4f0b20b5a81c37028d27b567ba52 Mon Sep 17 00:00:00 2001
From: Reid Kleckner <rnk@google.com>
Date: Wed, 11 May 2016 17:43:13 +0000
Subject: [PATCH] Relax -Wcalling-convention-cast when casting to the default
convention (cdecl)
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@269214 91177308-0d34-0410-b5e6-96231b3b80d8
---
lib/Sema/SemaCast.cpp | 10 +++++++++-
test/Sema/callingconv-cast.c | 9 +++++++++
2 files changed, 18 insertions(+), 1 deletion(-)
diff --git a/lib/Sema/SemaCast.cpp b/lib/Sema/SemaCast.cpp
index 646b884ce1a..1d95b1f9f18 100644
--- a/lib/Sema/SemaCast.cpp
+++ b/lib/Sema/SemaCast.cpp
@@ -1760,7 +1760,15 @@ static void DiagnoseCallingConvCast(Sema &Self, const ExprResult &SrcExpr,
if (!FD || !FD->hasBody(Definition))
return;
- // The source expression is a pointer to a known function defined in this TU.
+ // Only warn if we are casting from the default convention to a non-default
+ // convention. This can happen when the programmer forgot to apply the calling
+ // convention to the function definition and then inserted this cast to
+ // satisfy the type system.
+ CallingConv DefaultCC = Self.getASTContext().getDefaultCallingConvention(
+ FD->isVariadic(), FD->isCXXInstanceMember());
+ if (DstCC == DefaultCC || SrcCC != DefaultCC)
+ return;
+
// Diagnose this cast, as it is probably bad.
StringRef SrcCCName = FunctionType::getNameForCallConv(SrcCC);
StringRef DstCCName = FunctionType::getNameForCallConv(DstCC);
diff --git a/test/Sema/callingconv-cast.c b/test/Sema/callingconv-cast.c
index 9f1855baeb5..88b25e8f17a 100644
--- a/test/Sema/callingconv-cast.c
+++ b/test/Sema/callingconv-cast.c
@@ -21,6 +21,10 @@ void mismatched(int x) {}
typedef void (WINAPI *callback_t)(int);
void take_callback(callback_t callback);
+void WINAPI mismatched_stdcall(int x) {}
+
+void take_opaque_fn(void (*callback)(int));
+
int main() {
// expected-warning@+1 {{cast between incompatible calling conventions 'cdecl' and 'stdcall'}}
take_callback((callback_t)mismatched);
@@ -44,6 +48,11 @@ int main() {
// Another way to suppress the warning.
take_callback((callback_t)(void*)mismatched);
+
+ // Don't warn, because we're casting from stdcall to cdecl. Usually that means
+ // the programmer is rinsing the function pointer through some kind of opaque
+ // API.
+ take_opaque_fn((void (*)(int))mismatched_stdcall);
}
// MSFIXIT: fix-it:"{{.*}}callingconv-cast.c":{19:6-19:6}:"WINAPI "
--
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