Treat as external the global fields of an interface block (#431), fixes

#430

Interface blocks without an instance name introduce external global
variables.

src/ast.fs

@@ -79,8 +79,10 @@ and Expr =
 
 and TypeSpec =
     | TypeName of string
-    // e.g. struct foo { float x; float y; }
+    // struct or interface block, e.g. struct foo { float x; float y; }
     | TypeBlock of string(*type*) * Ident option(*name*) * Decl list
+    // An interface block followed by an instance name (in a TLDecl), like structs, declares an instance.
+    // An interface block without an instance name (in a TypeDecl), unlike structs, introduces a set of external global variables.
 
 and Type = {
     name: TypeSpec // e.g. int
@@ -167,7 +169,7 @@ and TopLevel =
     | TLDirective of string list
     | Function of FunctionType * Stmt
     | TLDecl of Decl
-    | TypeDecl of TypeSpec // structs
+    | TypeDecl of TypeSpec // structs or interface blocks
     | Precision of Type
 
 let makeType name tyQ sizes = {Type.name=name; typeQ=tyQ; arraySizes=sizes}

src/renamer.fs

@@ -234,11 +234,12 @@ type private RenamerImpl(options: Options.Options) =
             | e -> e
         mapExpr (mapEnvExpr options mapper) expr |> ignore<Expr>
 
-    let renDecl level env (ty:Type, vars) =
+    let renDecl level isFieldOfAnInterfaceBlockWithoutInstanceName env (ty:Type, vars) =
         let aux (env: Env) (decl: Ast.DeclElt) =
             Option.iter (renExpr env) decl.init
             Option.iter (renExpr env) decl.size
-            let isExternal = level = Level.TopLevel && (ty.IsExternal || options.hlsl)
+            let isExternal = (level = Level.TopLevel && (ty.IsExternal || options.hlsl)) ||
+                             isFieldOfAnInterfaceBlockWithoutInstanceName
 
             if (level = Level.TopLevel && options.preserveAllGlobals) ||
                     List.contains decl.name.Name options.noRenamingList then
@@ -280,7 +281,7 @@ type private RenamerImpl(options: Options.Options) =
         function
         | Expr e -> renExpr env e; env
         | Decl d ->
-            renDecl Level.InFunc env d
+            renDecl Level.InFunc false env d
         | Block b ->
             renList env renStmt b |> ignore<Env>
             env
@@ -291,7 +292,7 @@ type private RenamerImpl(options: Options.Options) =
             env
         | ForD(init, cond, inc, body) as stmt ->
             let newEnv = env.onEnterFunction env stmt
-            let newEnv = renDecl Level.InFunc newEnv init
+            let newEnv = renDecl Level.InFunc false newEnv init
             renStmt newEnv body |> ignore<Env>
             Option.iter (renExpr newEnv) cond
             Option.iter (renExpr newEnv) inc
@@ -332,20 +333,20 @@ type private RenamerImpl(options: Options.Options) =
     let renTyBlock (env: Env) = function
         | TypeBlock("struct", _, _) -> env
         | TypeBlock(_, _, fields) ->
-            // treat the fields as if they were global variables
-            renList env (renDecl Level.TopLevel) fields
+            // interface block without an instance name: the fields are treated as external global variables
+            renList env (renDecl Level.TopLevel true) fields
         | _ -> env
 
     let rec renTopLevelName env = function
-        | TLDecl d -> renDecl Level.TopLevel env d
+        | TLDecl d -> renDecl Level.TopLevel false env d
         | TypeDecl tyDecl -> renTyBlock env tyDecl
         | Function(fct, _) -> renFctName env fct
         | _ -> env
 
     let rec renTopLevelBody (env: Env) = function
         | Function(fct, body) ->
             let env = env.onEnterFunction env body
-            let env = renList env (renDecl Level.InFunc) fct.args
+            let env = renList env (renDecl Level.InFunc false) fct.args
             renStmt env body |> ignore<Env>
         | _ -> ()
 

tests/commands.txt

@@ -63,6 +63,7 @@
 # Multifile tests
 
 --no-remove-unused --move-declarations --format c-array -o tests/unit/inout.expected tests/unit/inout.frag tests/unit/inout2.frag
+--no-remove-unused --format c-array -o tests/unit/interface-block-renaming.expected tests/unit/interface-block-renaming1.frag tests/unit/interface-block-renaming2.frag
 
 # kkp symbols tests
 

tests/unit/interface-block-renaming.expected

@@ -0,0 +1,18 @@
+// Generated with  (https://github.com/laurentlb/Shader_Minifier/)
+#ifndef SHADER_MINIFIER_IMPL
+#ifndef SHADER_MINIFIER_HEADER
+# define SHADER_MINIFIER_HEADER
+# define VAR_field "U"
+#endif
+
+#else // if SHADER_MINIFIER_IMPL
+
+// tests/unit/interface-block-renaming1.frag
+ "#version 460\n"
+ "uniform Uniform1{vec4 U;};",
+
+// tests/unit/interface-block-renaming2.frag
+ "#version 460\n"
+ "uniform Uniform1{vec4 U;};",
+
+#endif

tests/unit/interface-block-renaming1.frag

@@ -0,0 +1,4 @@
+#version 460
+// https://github.com/laurentlb/shader-minifier/issues/430
+uniform Uniform1 { vec4 field; };
+//uniform Uniform2 { vec4 field; } instance; // TODO

tests/unit/interface-block-renaming2.frag

@@ -0,0 +1,4 @@
+#version 460
+// https://github.com/laurentlb/shader-minifier/issues/430
+uniform Uniform1 { vec4 field; };
+//uniform Uniform2 { vec4 field; } instance; // TODO