From b56fa1d1b02c93151f0a25d868f4459cac8d6a4d Mon Sep 17 00:00:00 2001
From: k-hara <k.hara.pg@gmail.com>
Date: Sat, 6 Feb 2016 16:03:41 +0900
Subject: [PATCH] fix Issue 15490 - Error variable __nrvoretval cannot be
 modified at compile time when using -inline

CTFE interpretr can recognize a form `CommaExp(DeclaraationExp(v), VarExp(v))` as
a CTFEable variable declaration when `v._init` is `null`. In other cases, for
examle a sole `DeclarationExp` should have v._init for CTFE-ability.

Supply `VoidInitializer` to allow inlining the temporary for NRVO.
---
 src/dinterpret.d                    |  6 +++++-
 src/inline.d                        |  2 +-
 test/compilable/imports/imp15490a.d |  8 ++++++++
 test/compilable/imports/imp15490b.d | 12 ++++++++++++
 test/compilable/test15490.d         | 12 ++++++++++++
 5 files changed, 38 insertions(+), 2 deletions(-)
 create mode 100644 test/compilable/imports/imp15490a.d
 create mode 100644 test/compilable/imports/imp15490b.d
 create mode 100644 test/compilable/test15490.d

diff --git a/src/dinterpret.d b/src/dinterpret.d
index cb9d04bcfbc7..60a06deefad6 100644
--- a/src/dinterpret.d
+++ b/src/dinterpret.d
@@ -4916,9 +4916,13 @@ public:
             istate = &istateComma;
         }
         result = CTFEExp.cantexp;
+
         // If the comma returns a temporary variable, it needs to be an lvalue
         // (this is particularly important for struct constructors)
-        if (e.e1.op == TOKdeclaration && e.e2.op == TOKvar && (cast(DeclarationExp)e.e1).declaration == (cast(VarExp)e.e2).var && (cast(VarExp)e.e2).var.storage_class & STCctfe) // same as Expression::isTemp
+        if (e.e1.op == TOKdeclaration &&
+            e.e2.op == TOKvar &&
+            (cast(DeclarationExp)e.e1).declaration == (cast(VarExp)e.e2).var &&
+            (cast(VarExp)e.e2).var.storage_class & STCctfe)
         {
             VarExp ve = cast(VarExp)e.e2;
             VarDeclaration v = ve.var.isVarDeclaration();
diff --git a/src/inline.d b/src/inline.d
index 50ab0176a1f1..137112f31684 100644
--- a/src/inline.d
+++ b/src/inline.d
@@ -2116,7 +2116,7 @@ void expandInline(FuncDeclaration fd, FuncDeclaration parent, Expression eret,
         else
         {
             Identifier tmp = Identifier.generateId("__nrvoretval");
-            auto vd = new VarDeclaration(fd.loc, fd.nrvo_var.type, tmp, null);
+            auto vd = new VarDeclaration(fd.loc, fd.nrvo_var.type, tmp, new VoidInitializer(fd.loc));
             assert(!tf.isref);
             vd.storage_class = STCtemp | STCrvalue;
             vd.linkage = tf.linkage;
diff --git a/test/compilable/imports/imp15490a.d b/test/compilable/imports/imp15490a.d
new file mode 100644
index 000000000000..edb3b45e6002
--- /dev/null
+++ b/test/compilable/imports/imp15490a.d
@@ -0,0 +1,8 @@
+module imports.imp15490a;
+
+import imports.imp15490b;
+
+void listenTCP()
+{
+    enum r = regex();
+}
diff --git a/test/compilable/imports/imp15490b.d b/test/compilable/imports/imp15490b.d
new file mode 100644
index 000000000000..3a2490c9f6c9
--- /dev/null
+++ b/test/compilable/imports/imp15490b.d
@@ -0,0 +1,12 @@
+module imports.imp15490b;
+
+int regex()
+{
+    return regexImpl();
+}
+
+auto regexImpl()
+{
+    int r = 0;
+    return r;
+}
diff --git a/test/compilable/test15490.d b/test/compilable/test15490.d
new file mode 100644
index 000000000000..eab5c61a74c8
--- /dev/null
+++ b/test/compilable/test15490.d
@@ -0,0 +1,12 @@
+// REQUIRED_ARGS: -o- -inline
+// PERMUTE_ARGS:
+module test15490;
+
+import imports.imp15490a;
+import imports.imp15490b;
+
+void main()
+{
+    regex();
+    listenTCP();
+}