[clang] fixing conditional explicit for out-of-line definition PR42980

[Tyker]

Summary

not every read in CXXConstructorDecl::getExplicitSpecifierInternal() was made on the canonical declaration.

cfe/trunk/include/clang/AST/DeclCXX.h

size_t numTrailingObjects(OverloadToken<InheritedConstructor>) const {
     return CXXConstructorDeclBits.IsInheritingConstructor;
   }
   size_t numTrailingObjects(OverloadToken<ExplicitSpecifier>) const {
     return CXXConstructorDeclBits.HasTrailingExplicitSpecifier;
   }
 
   ExplicitSpecifier getExplicitSpecifierInternal() const {
     if (CXXConstructorDeclBits.HasTrailingExplicitSpecifier)
-      return *getCanonicalDecl()->getTrailingObjects<ExplicitSpecifier>();
+      return *getTrailingObjects<ExplicitSpecifier>();
     return ExplicitSpecifier(
-        nullptr, getCanonicalDecl()->CXXConstructorDeclBits.IsSimpleExplicit
+        nullptr, CXXConstructorDeclBits.IsSimpleExplicit
                      ? ExplicitSpecKind::ResolvedTrue
                      : ExplicitSpecKind::ResolvedFalse);
   }
 
   void setExplicitSpecifier(ExplicitSpecifier ES) {
     assert((!ES.getExpr() ||
             CXXConstructorDeclBits.HasTrailingExplicitSpecifier) &&
            "cannot set this explicit specifier. no trail-allocated space for "
public:
   static CXXConstructorDecl *
   Create(ASTContext &C, CXXRecordDecl *RD, SourceLocation StartLoc,
          const DeclarationNameInfo &NameInfo, QualType T, TypeSourceInfo *TInfo,
          ExplicitSpecifier ES, bool isInline, bool isImplicitlyDeclared,
          ConstexprSpecKind ConstexprKind,
          InheritedConstructor Inherited = InheritedConstructor());
 
   ExplicitSpecifier getExplicitSpecifier() {
-    return getExplicitSpecifierInternal();
+    return getCanonicalDecl()->getExplicitSpecifierInternal();
   }
   const ExplicitSpecifier getExplicitSpecifier() const {
-    return getExplicitSpecifierInternal();
+    return getCanonicalDecl()->getExplicitSpecifierInternal();
   }
 
   /// Return true if the declartion is already resolved to be explicit.
   bool isExplicit() const { return getExplicitSpecifier().isExplicit(); }
 
   /// Iterates through the member/base initializer list.
   using init_iterator = CXXCtorInitializer **;
 

cfe/trunk/test/SemaCXX/cxx2a-explicit-bool.cpp

 A c3 = {0, 0};// expected-error {{explicit deduction guide}}
 
 A d0 = 0.0; // expected-error {{no viable constructor or deduction guide}}
 A d1(0, 0);
 A d2{0, 0};
 A d3 = {0.0, 0.0};// expected-error {{explicit deduction guide}}
 
 }
+
+namespace PR42980 {
+using size_t = decltype(sizeof(0));
+
+struct Str {// expected-note+ {{candidate constructor}}
+  template <size_t N>
+  explicit(N > 7)// expected-note {{resolved to true}}
+  Str(char const (&str)[N]);
+};
+
+template <size_t N>
+Str::Str(char const(&str)[N]) { }
+// expected-note@-1 {{candidate constructor}}
+
+Str a = "short";
+Str b = "not so short";// expected-error {{no viable conversion}}
+
+}
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