[Sema] Check existence of GenericSignature before getting GenericParamList from it

Fixes 2 compiler crasher.

Author: rintaro

lib/Sema/TypeCheckAttr.cpp

@@ -1408,11 +1408,14 @@ void AttributeChecker::visitSpecializeAttr(SpecializeAttr *attr) {
   auto *FD = cast<AbstractFunctionDecl>(D);
   auto *genericSig = FD->getGenericSignature();
 
-  unsigned numTypes = genericSig->getGenericParams().size();
+  unsigned numTypes = 0;
+  if (genericSig)
+    numTypes = genericSig->getGenericParams().size();
   if (numTypes != attr->getTypeLocs().size()) {
     TC.diagnose(attr->getLocation(), diag::type_parameter_count_mismatch,
                 FD->getName(), numTypes, attr->getTypeLocs().size(),
                 numTypes > attr->getTypeLocs().size());
+    attr->setInvalid();
     return;
   }
   // Initialize each TypeLoc in this attribute with a concrete type,

test/attr/attr_specialize.swift

@@ -23,6 +23,9 @@ public func twoGenericParams<T, U>(_ t: T, u: U) -> (T, U) {
   return (t, u)
 }
 
+@_specialize(Int) // expected-error{{generic type 'nonGenericParam' specialized with too many type parameters (got 1, but expected 0)}}
+func nonGenericParam(x: Int) {}
+
 // Specialize contextual types.
 // ----------------------------
 

validation-test/SIL/crashers/030-swift-typechecker-checkdeclattributes.sil renamed to validation-test/SIL/crashers_fixed/030-swift-typechecker-checkdeclattributes.sil

@@ -1,3 +1,3 @@
-// RUN: not --crash %target-sil-opt %s
+// RUN: not %target-sil-opt %s
 // REQUIRES: asserts
 @_specialize(h)func f

validation-test/compiler_crashers/28511-swift-astvisitor-anonymous-namespace-attributechecker-void-void-void-void-void-v.swift renamed to validation-test/compiler_crashers_fixed/28511-swift-astvisitor-anonymous-namespace-attributechecker-void-void-void-void-void-v.swift

@@ -5,5 +5,5 @@
 // See http://swift.org/LICENSE.txt for license information
 // See http://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
 
-// RUN: not --crash %target-swift-frontend %s -emit-ir
+// RUN: not %target-swift-frontend %s -emit-ir
 @_specialize(s)func r