Prevent structs/interface-blocks from claiming builtin types.

Structs and interface blocks allow a trailing identifier which is added
to the symbol table. This identifier is now prohibited from
overlapping built-in types.

Change-Id: I33b9d6156a27ce017e6744a05979748c04a04767
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/489516
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: John Stiles <johnstiles@google.com>
Auto-Submit: John Stiles <johnstiles@google.com>

src/sksl/SkSLDSLParser.cpp

@@ -212,6 +212,17 @@ bool DSLParser::expectIdentifier(Token* result) {
     return true;
 }
 
+bool DSLParser::checkIdentifier(Token* result) {
+    if (!this->checkNext(Token::Kind::TK_IDENTIFIER, result)) {
+        return false;
+    }
+    if (IsBuiltinType(this->text(*result))) {
+        this->pushback(std::move(*result));
+        return false;
+    }
+    return true;
+}
+
 skstd::string_view DSLParser::text(Token token) {
     return skstd::string_view(fText->data() + token.fOffset, token.fLength);
 }
@@ -645,9 +656,9 @@ SkTArray<dsl::DSLGlobalVar> DSLParser::structVarDeclaration(const DSLModifiers&
         return {};
     }
     Token name;
-    if (this->checkNext(Token::Kind::TK_IDENTIFIER, &name)) {
+    if (this->checkIdentifier(&name)) {
         this->globalVarDeclarationEnd(this->position(name), modifiers, std::move(*type),
-                this->text(name));
+                                      this->text(name));
     } else {
         this->expect(Token::Kind::TK_SEMICOLON, "';'");
     }
@@ -901,7 +912,7 @@ bool DSLParser::interfaceBlock(const dsl::DSLModifiers& modifiers) {
     skstd::string_view instanceName;
     Token instanceNameToken;
     SKSL_INT arraySize = 0;
-    if (this->checkNext(Token::Kind::TK_IDENTIFIER, &instanceNameToken)) {
+    if (this->checkIdentifier(&instanceNameToken)) {
         instanceName = this->text(instanceNameToken);
         if (this->checkNext(Token::Kind::TK_LBRACKET)) {
             arraySize = this->arraySize();

src/sksl/SkSLDSLParser.h

@@ -88,6 +88,13 @@ private:
      */
     bool checkNext(Token::Kind kind, Token* result = nullptr);
 
+    /**
+     * Behaves like checkNext(TK_IDENTIFIER), but also verifies that identifier is not a builtin
+     * type. If the token was actually a builtin type, false is returned (the next token is not
+     * considered to be an identifier).
+     */
+    bool checkIdentifier(Token* result = nullptr);
+
     /**
      * Reads the next non-whitespace token and generates an error if it is not the expected type.
      * The 'expected' string is part of the error message, which reads:

tests/sksl/errors/InterfaceBlockReservedName.glsl

@@ -1,7 +1,4 @@
+### Compilation failed:
 
-IB {
-    float f;
-} float;
-vec4 main() {
-    return vec4(float.f);
-}
+error: 3: expected ';', but found 'float'
+1 error

tests/sksl/errors/StructVariableReservedName.glsl

@@ -1,8 +1,4 @@
+### Compilation failed:
 
-struct S {
-    float f;
-};
-S float;
-vec4 main() {
-    return vec4(float.f);
-}
+error: 3: expected ';', but found 'float'
+1 error