Disallow multiple locations on output variables

samples/shader_translator/shader_translator.cpp

@@ -222,6 +222,10 @@ int main(int argc, char *argv[])
         }
         else
         {
+            if (spec != SH_GLES2_SPEC && spec != SH_WEBGL_SPEC)
+            {
+                resources.MaxDrawBuffers = 8;
+            }
             ShHandle compiler = 0;
             switch (FindShaderType(argv[0]))
             {

src/compiler/translator/BaseTypes.h

@@ -387,6 +387,7 @@ enum TLayoutBlockStorage
 struct TLayoutQualifier
 {
     int location;
+    unsigned int locationsSpecified;
     TLayoutMatrixPacking matrixPacking;
     TLayoutBlockStorage blockStorage;
 
@@ -398,6 +399,7 @@ struct TLayoutQualifier
         TLayoutQualifier layoutQualifier;
 
         layoutQualifier.location = -1;
+        layoutQualifier.locationsSpecified = 0;
         layoutQualifier.matrixPacking = EmpUnspecified;
         layoutQualifier.blockStorage = EbsUnspecified;
 

src/compiler/translator/ParseContext.cpp

@@ -2935,6 +2935,7 @@ TLayoutQualifier TParseContext::parseLayoutQualifier(const TString &qualifierTyp
         else
         {
             qualifier.location = intValue;
+            qualifier.locationsSpecified = 1;
         }
     }
     else if (qualifierType == "local_size_x")

src/compiler/translator/QualifierTypes.cpp

@@ -22,6 +22,7 @@ TLayoutQualifier JoinLayoutQualifiers(TLayoutQualifier leftQualifier,
     if (rightQualifier.location != -1)
     {
         joinedQualifier.location = rightQualifier.location;
+        ++joinedQualifier.locationsSpecified;
     }
     if (rightQualifier.matrixPacking != EmpUnspecified)
     {
@@ -98,6 +99,9 @@ bool HasRepeatingQualifiers(const TTypeQualifierBuilder::QualifierSequence &qual
     bool layoutFound        = false;
     bool interpolationFound = false;
 
+    unsigned int locationsSpecified = 0;
+    bool isOut                      = false;
+
     // The iteration starts from one since the first qualifier only reveals the scope of the
     // expression. It is inserted first whenever the sequence gets created.
     for (size_t i = 1; i < qualifiers.size(); ++i)
@@ -132,6 +136,9 @@ bool HasRepeatingQualifiers(const TTypeQualifierBuilder::QualifierSequence &qual
                     return true;
                 }
                 layoutFound = true;
+                const TLayoutQualifier &currentQualifier =
+                    static_cast<const TLayoutQualifierWrapper *>(qualifiers[i])->getQualifier();
+                locationsSpecified += currentQualifier.locationsSpecified;
                 break;
             }
             case QtInterpolation:
@@ -153,6 +160,10 @@ bool HasRepeatingQualifiers(const TTypeQualifierBuilder::QualifierSequence &qual
                 // repetitions.
                 TQualifier currentQualifier =
                     static_cast<const TStorageQualifierWrapper *>(qualifiers[i])->getQualifier();
+                if (currentQualifier == EvqVertexOut || currentQualifier == EvqFragmentOut)
+                {
+                    isOut = true;
+                }
                 for (size_t j = 1; j < i; ++j)
                 {
                     if (qualifiers[j]->getType() == QtStorage)
@@ -175,6 +186,15 @@ bool HasRepeatingQualifiers(const TTypeQualifierBuilder::QualifierSequence &qual
         }
     }
 
+    if (locationsSpecified > 1 && isOut)
+    {
+        // GLSL ES 3.00.6 section 4.3.8.2 Output Layout Qualifiers
+        // GLSL ES 3.10 section 4.4.2 Output Layout Qualifiers
+        // "The qualifier may appear at most once within a declaration."
+        *errorMessage = "Output layout location specified multiple times.";
+        return true;
+    }
+
     return false;
 }
 

src/tests/compiler_tests/QualificationOrder_test.cpp

@@ -27,6 +27,7 @@ class QualificationOrderShaderTest : public testing::Test
     {
         ShBuiltInResources resources;
         ShInitBuiltInResources(&resources);
+        resources.MaxDrawBuffers = (spec == SH_GLES2_SPEC) ? 1 : 8;
 
         TranslatorESSL *translator = new TranslatorESSL(shaderType, spec);
         EXPECT_TRUE(translator->Init(resources));
@@ -549,3 +550,20 @@ TEST_F(QualificationOrderShaderTest, InvalidFunctionParametersFlatIn)
         FAIL() << "Shader compilation succeeded, expecting failure" << mInfoLog;
     }
 }
+
+// Output layout location qualifier can't appear more than once within a declaration.
+// GLSL ES 3.00.6 section 4.3.8.2 Output Layout Qualifiers.
+TEST_F(QualificationOrderShaderTest, TwoOutputLocations)
+{
+    const std::string &shaderString =
+        "#version 300 es\n"
+        "precision mediump float;\n"
+        "layout(location=1, location=2) out vec4 myColor;\n"
+        "void main() {\n"
+        "}\n";
+
+    if (compile(shaderString, GL_FRAGMENT_SHADER, SH_GLES3_SPEC))
+    {
+        FAIL() << "Shader compilation succeeded, expecting failure " << mInfoLog;
+    }
+}