Converting SPIR-V to MSL leads to use of undeclared variable

[jiradeto]

I was trying to convert SPIR-V to MSL using SPIRV-Cross and found that when a GLSL shader has variable declarations inside a switch statement like the following:

// GLSL:
switch(0)
 {
   case 0:
     int a = 1;   
   case 1:
     int b = 1;
   case 2:
     int c = 1;  
 }

SPIRV-Cross seems to move all declarations in each case into the first case of the switch statement leading to an invalid shader:

 // MSL:
 switch (0)
   {
       case 0:
       {
           int a = 1;
           int b = 1;
           int c = 1;
           break;
       }
       case 1:
       {
           b = 1; // error: use of undeclared identifier 'b'
           c = 1;
           break;
       }
       case 2:
       {
           c = 1;
           break;
       }
   }

Versions:

• SPIRV-Cross: built from source (commit 05ea055096df8b7b8b3e3f7e121279acf83f74c0)
• glslangValidator: Glslang Version: 7.12.3226

Steps to reproduce:

• Convert the GLSL shader to SPIR-V using glslangValidator with the command glslangValidator -V sample.frag -o sample.spv
• Convert the SPIR-V to MSL using SPIRV-Cross with the command spirv-cross --msl sample.spv --output result.msl

Note that before running SPIRV-Cross, I also used spirv-val to check that the SPIR-V produced by glslangValidator is valid.

This archive contains the original fragment shader, the associated SPIR-V, and MSL shader.

Issue found using GraphicsFuzz.

[HansKristian-Work]

Pretty sure this is due to lack of fall-through case handling in SPIRV-Cross, but I'll need to reproduce first.

[HansKristian-Work]

This was kind of fixed two weeks ago, but the code-gen is still duplicated, so that needs to be fixed.