[gcc r12-8980] d: Fix undefined reference to nested lambda in template (PR108055)

[gcc r12-8980] d: Fix undefined reference to nested lambda in template (PR108055)

[Iain Buclaw]

https://gcc.gnu.org/g:3b8b42f32627ca5ad029fe418a5839b9fc4512e9

commit r12-8980-g3b8b42f32627ca5ad029fe418a5839b9fc4512e9
Author: Iain Buclaw <ibuclaw@gdcproject.org>
Date:   Sat Dec 10 22:11:41 2022 +0100

    d: Fix undefined reference to nested lambda in template (PR108055)
    
    Sometimes, nested lambdas of templated functions get no code generation
    due to them being marked as instantianted outside of all modules being
    compiled in the current compilation unit.  This despite enclosing
    template instances being marked as instantiated inside the current
    compilation unit.  To fix, all enclosing templates are now checked in
    `function_defined_in_root_p'.
    
    Because of this change, `function_needs_inline_definition_p' has also
    been fixed up to only check whether the regular function definition
    itself is to be emitted in the current compilation unit.
    
            PR d/108055
    
    gcc/d/ChangeLog:
    
            * decl.cc (function_defined_in_root_p): Check all enclosing template
            instances for definition in a root module.
            (function_needs_inline_definition_p): Replace call to
            function_defined_in_root_p with test for outer module `isRoot'.
    
    gcc/testsuite/ChangeLog:
    
            * gdc.dg/torture/imports/pr108055conv.d: New.
            * gdc.dg/torture/imports/pr108055spec.d: New.
            * gdc.dg/torture/imports/pr108055write.d: New.
            * gdc.dg/torture/pr108055.d: New test.
    
    (cherry picked from commit 9fe7d3debbf60ed9fef8053123ad542a99d62100)

Diff:
---
 gcc/d/decl.cc                                      | 14 +++++++-----
 .../gdc.dg/torture/imports/pr108055conv.d          | 26 ++++++++++++++++++++++
 .../gdc.dg/torture/imports/pr108055spec.d          | 18 +++++++++++++++
 .../gdc.dg/torture/imports/pr108055write.d         | 19 ++++++++++++++++
 gcc/testsuite/gdc.dg/torture/pr108055.d            | 12 ++++++++++
 5 files changed, 84 insertions(+), 5 deletions(-)

diff --git a/gcc/d/decl.cc b/gcc/d/decl.cc
index e62be0c580a..11fd7f6c81f 100644
--- a/gcc/d/decl.cc
+++ b/gcc/d/decl.cc
@@ -1023,7 +1023,8 @@ build_decl_tree (Dsymbol *d)
   input_location = saved_location;
 }
 
-/* Returns true if function FD is defined or instantiated in a root module.  */
+/* Returns true if function FD, or any lexically enclosing scope function of FD
+   is defined or instantiated in a root module.  */
 
 static bool
 function_defined_in_root_p (FuncDeclaration *fd)
@@ -1032,9 +1033,11 @@ function_defined_in_root_p (FuncDeclaration *fd)
   if (md && md->isRoot ())
     return true;
 
-  TemplateInstance *ti = fd->isInstantiated ();
-  if (ti && ti->minst && ti->minst->isRoot ())
-    return true;
+  for (TemplateInstance *ti = fd->isInstantiated (); ti != NULL; ti = ti->tinst)
+    {
+      if (ti->minst && ti->minst->isRoot ())
+	return true;
+    }
 
   return false;
 }
@@ -1062,7 +1065,8 @@ function_needs_inline_definition_p (FuncDeclaration *fd)
 
   /* Check whether function will be regularly defined later in the current
      translation unit.  */
-  if (function_defined_in_root_p (fd))
+  Module *md = fd->getModule ();
+  if (md && md->isRoot ())
     return false;
 
   /* Non-inlineable functions are always external.  */
diff --git a/gcc/testsuite/gdc.dg/torture/imports/pr108055conv.d b/gcc/testsuite/gdc.dg/torture/imports/pr108055conv.d
new file mode 100644
index 00000000000..93ebba747b1
--- /dev/null
+++ b/gcc/testsuite/gdc.dg/torture/imports/pr108055conv.d
@@ -0,0 +1,26 @@
+module imports.pr108055conv;
+
+T toStr(T, S)(S src)
+{
+    static if (is(typeof(T.init[0]) E))
+    {
+        struct Appender
+        {
+            inout(E)[] data;
+        }
+
+        import imports.pr108055spec;
+        import imports.pr108055write;
+
+        auto w = Appender();
+        FormatSpec!E f;
+        formatValue(w, src, f);
+        return w.data;
+    }
+}
+
+T to(T, A)(A args)
+{
+    return toStr!T(args);
+}
+
diff --git a/gcc/testsuite/gdc.dg/torture/imports/pr108055spec.d b/gcc/testsuite/gdc.dg/torture/imports/pr108055spec.d
new file mode 100644
index 00000000000..801c5810516
--- /dev/null
+++ b/gcc/testsuite/gdc.dg/torture/imports/pr108055spec.d
@@ -0,0 +1,18 @@
+module imports.pr108055spec;
+
+template Unqual(T : const U, U)
+{
+    alias Unqual = U;
+}
+
+template FormatSpec(Char)
+if (!is(Unqual!Char == Char))
+{
+    alias FormatSpec = FormatSpec!(Unqual!Char);
+}
+
+struct FormatSpec(Char)
+if (is(Unqual!Char == Char))
+{
+    const(Char)[] nested;
+}
diff --git a/gcc/testsuite/gdc.dg/torture/imports/pr108055write.d b/gcc/testsuite/gdc.dg/torture/imports/pr108055write.d
new file mode 100644
index 00000000000..fe41d7baa7c
--- /dev/null
+++ b/gcc/testsuite/gdc.dg/torture/imports/pr108055write.d
@@ -0,0 +1,19 @@
+module imports.pr108055write;
+import imports.pr108055spec;
+
+void formatValueImpl(Writer, T, Char)(ref Writer , const(T) ,
+                                      scope const ref FormatSpec!Char )
+{
+    T val;
+    char spec;
+
+    (ref val) @trusted {
+        return (cast(const char*) &val)[0 .. val.sizeof];
+    }(val);
+
+}
+
+void formatValue(Writer, T, Char)(Writer w, T val, Char f)
+{
+    formatValueImpl(w, val, f);
+}
diff --git a/gcc/testsuite/gdc.dg/torture/pr108055.d b/gcc/testsuite/gdc.dg/torture/pr108055.d
new file mode 100644
index 00000000000..c4ffad26d1e
--- /dev/null
+++ b/gcc/testsuite/gdc.dg/torture/pr108055.d
@@ -0,0 +1,12 @@
+// { dg-do link }
+// { dg-additional-files "imports/pr108055conv.d imports/pr108055spec.d imports/pr108055write.d" }
+// { dg-additional-options "-I[srcdir] -fno-druntime" }
+import imports.pr108055conv;
+
+extern(C) int main()
+{
+    float zis;
+    static if (is(typeof(to!string(&zis))))
+        to!string(&zis);
+    return 0;
+}