Overload selection: call procvars if result is compatible with parameter

Previously we only autmatically called procvars without parameters in TP/Delphi
modes if their result type was equal to the parameter type to which they were
passed. Resolves #39748.

compiler/htypechk.pas

@@ -2960,23 +2960,23 @@ implementation
               { Convert tp procvars when not expecting a procvar }
              if (currpt.left.resultdef.typ=procvardef) and
                 not(def_to.typ in [procvardef,formaldef]) and
-                 { Only convert to call when there is no overload or the return type
-                   is equal to the expected type. }
-                 (
-                  (count=1) or
-                  equal_defs(tprocvardef(currpt.left.resultdef).returndef,def_to)
-                 ) and
-                 { and if it doesn't require any parameters }
-                 (tprocvardef(currpt.left.resultdef).minparacount=0)  then
-                begin
-                  releasecurrpt:=true;
-                  currpt:=tcallparanode(pt.getcopy);
-                  if maybe_call_procvar(currpt.left,true) then
-                    begin
-                      currpt.resultdef:=currpt.left.resultdef;
-                      def_from:=currpt.left.resultdef;
-                    end;
-                end;
+                { if it doesn't require any parameters }
+                (tprocvardef(currpt.left.resultdef).minparacount=0) and
+                { Only convert to call when there is no overload or the return type
+                  is compatible with the expected type. }
+                (
+                 (count=1) or
+                 (compare_defs_ext(tprocvardef(currpt.left.resultdef).returndef,def_to,nothingn,convtype,pdoper,[])>te_incompatible)
+                ) then
+               begin
+                 releasecurrpt:=true;
+                 currpt:=tcallparanode(pt.getcopy);
+                 if maybe_call_procvar(currpt.left,true) then
+                   begin
+                     currpt.resultdef:=currpt.left.resultdef;
+                     def_from:=currpt.left.resultdef;
+                   end;
+               end;
 
              { If we expect a procvar and the left is loadnode that
                returns a procdef we need to find the correct overloaded

tests/webtbs/tw39748.pp

@@ -0,0 +1,18 @@
+{$mode delphi}
+uses
+  sysutils;
+type
+  glenum=word;
+  TglGetError = function(): GLenum; cdecl;
+
+function test: glenum; cdecl;
+begin
+  result:=42;
+end;
+
+var glgeterror : TGlGeterror;
+begin
+  glgeterror:=test;
+  if inttostr(glgeterror)<>'42' then
+    halt(1);
+end.

tests/webtbs/tw39748a.pp

@@ -0,0 +1,27 @@
+{$mode delphi}
+type
+  glenum=word;
+  TglGetError = function(): GLenum; cdecl;
+
+function test: glenum; cdecl;
+begin
+  result:=42;
+end;
+
+procedure call(e: longint); overload;
+begin
+  writeln('longint');
+  halt(1);
+end;
+
+procedure call(p :tglgeterror); overload;
+begin
+  writeln('procvar');
+end;
+
+var glgeterror : TGlGeterror;
+begin
+  glgeterror:=test;
+  call(glgeterror)
+end.
+