From: David Majnemer <david.majnemer@gmail.com>
Date: Wed, 23 Oct 2013 21:31:20 +0000 (+0000)
Subject: Parse: Disable delayed template parsing for constexpr functions
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=645526c3e42170e356f792b1bc0ac2acb65c26c4;p=clang

Parse: Disable delayed template parsing for constexpr functions

Commit r191484 treated constexpr function templates as normal function
templates with respect to delaying their parsing.  However, this is
unnecessarily restrictive because there is no compatibility concern with
constexpr, MSVC doesn't support it.

Instead, simply disable delayed template parsing for constexpr function
templates.  This largely reverts the changes made in r191484 but keeps
it's unit test.

This fixes PR17661.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@193274 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/Parse/ParseCXXInlineMethods.cpp b/lib/Parse/ParseCXXInlineMethods.cpp
index 6bab7988cf..863a09e89d 100644
--- a/lib/Parse/ParseCXXInlineMethods.cpp
+++ b/lib/Parse/ParseCXXInlineMethods.cpp
@@ -115,6 +115,7 @@ NamedDecl *Parser::ParseCXXInlineMethodDef(AccessSpecifier AS,
   // the tokens and store them for parsing at the end of the translation unit.
   if (getLangOpts().DelayedTemplateParsing &&
       DefinitionKind == FDK_Definition &&
+      !D.getDeclSpec().isConstexprSpecified() &&
       ((Actions.CurContext->isDependentContext() ||
         (TemplateInfo.Kind != ParsedTemplateInfo::NonTemplate &&
          TemplateInfo.Kind != ParsedTemplateInfo::ExplicitSpecialization)) &&
diff --git a/lib/Parse/Parser.cpp b/lib/Parse/Parser.cpp
index 9b6c97ac19..d95546af8a 100644
--- a/lib/Parse/Parser.cpp
+++ b/lib/Parse/Parser.cpp
@@ -990,9 +990,9 @@ Decl *Parser::ParseFunctionDefinition(ParsingDeclarator &D,
 
   // In delayed template parsing mode, for function template we consume the
   // tokens and store them for late parsing at the end of the translation unit.
-  if (getLangOpts().DelayedTemplateParsing &&
-      Tok.isNot(tok::equal) &&
-      TemplateInfo.Kind == ParsedTemplateInfo::Template) {
+  if (getLangOpts().DelayedTemplateParsing && Tok.isNot(tok::equal) &&
+      TemplateInfo.Kind == ParsedTemplateInfo::Template &&
+      !D.getDeclSpec().isConstexprSpecified()) {
     MultiTemplateParamsArg TemplateParameterLists(*TemplateInfo.TemplateParams);
     
     ParseScope BodyScope(this, Scope::FnScope|Scope::DeclScope);
diff --git a/lib/Sema/SemaExpr.cpp b/lib/Sema/SemaExpr.cpp
index 56eeab3bea..c842ed035d 100644
--- a/lib/Sema/SemaExpr.cpp
+++ b/lib/Sema/SemaExpr.cpp
@@ -11088,8 +11088,7 @@ void Sema::MarkFunctionReferenced(SourceLocation Loc, FunctionDecl *Func) {
     // However, they cannot be referenced if they are deleted, and they are
     // deleted whenever the implicit definition of the special member would
     // fail.
-    if (!(Func->isConstexpr() && !getLangOpts().DelayedTemplateParsing) ||
-        Func->getBody())
+    if (!Func->isConstexpr() || Func->getBody())
       return;
     CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(Func);
     if (!Func->isImplicitlyInstantiable() && (!MD || MD->isUserProvided()))
@@ -11180,14 +11179,13 @@ void Sema::MarkFunctionReferenced(SourceLocation Loc, FunctionDecl *Func) {
       }
     }
 
-    if (!AlreadyInstantiated ||
-        (Func->isConstexpr() && !getLangOpts().DelayedTemplateParsing)) {
+    if (!AlreadyInstantiated || Func->isConstexpr()) {
       if (isa<CXXRecordDecl>(Func->getDeclContext()) &&
           cast<CXXRecordDecl>(Func->getDeclContext())->isLocalClass() &&
           ActiveTemplateInstantiations.size())
         PendingLocalImplicitInstantiations.push_back(
             std::make_pair(Func, PointOfInstantiation));
-      else if (Func->isConstexpr() && !getLangOpts().DelayedTemplateParsing)
+      else if (Func->isConstexpr())
         // Do not defer instantiations of constexpr functions, to avoid the
         // expression evaluator needing to call back into Sema if it sees a
         // call to such a function.
diff --git a/test/Parser/DelayedTemplateParsing.cpp b/test/Parser/DelayedTemplateParsing.cpp
index 201fe1b466..73128c49f2 100644
--- a/test/Parser/DelayedTemplateParsing.cpp
+++ b/test/Parser/DelayedTemplateParsing.cpp
@@ -114,3 +114,10 @@ void LLVMBuildStructGEP() { CreateConstInBoundsGEP2_32(); }
 
 }
 
+namespace PR17661 {
+template <typename T>
+constexpr T Fun(T A) { return T(0); }
+
+constexpr int Var = Fun(20);
+}
+