Add unit test for int/float mismatch error detection.

The "disallowed" tests are largely allowed in the current code, but all
fail properly in the followup CL.

Change-Id: I8e03570165480b60db9701ac1a782e1124ded56b
Bug: skia:11164
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/353617
Commit-Queue: John Stiles <johnstiles@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
Auto-Submit: John Stiles <johnstiles@google.com>

gn/sksl_tests.gni

@@ -103,6 +103,7 @@ sksl_error_tests = [
   "$_tests/sksl/errors/ForTypeMismatch.sksl",
   "$_tests/sksl/errors/GenericArgumentMismatch.sksl",
   "$_tests/sksl/errors/IfTypeMismatch.sksl",
+  "$_tests/sksl/errors/IntFloatMismatch.sksl",
   "$_tests/sksl/errors/InVarWithInitializerExpression.sksl",
   "$_tests/sksl/errors/InterfaceBlockScope.sksl",
   "$_tests/sksl/errors/InterfaceBlockStorageModifiers.sksl",

tests/sksl/errors/IntFloatMismatch.sksl

@@ -0,0 +1,34 @@
+int    i = 1;
+float  f = 1.0;
+
+// SkSL allows `float op <int literal>` and `<int literal> op float`, unlike GLSL.
+void   f_eq_int_literal_ok()               { f = 1; }
+void   f_plus_int_literal_ok()             { f + 1; }
+void   f_minus_int_literal_ok()            { f - 1; }
+void   f_mul_int_literal_ok()              { f * 1; }
+void   f_div_int_literal_ok()              { f / 1; }
+void   int_literal_plus_f_ok()             { 1 + f; }
+void   int_literal_minus_f_ok()            { 1 - f; }
+void   int_literal_mul_f_ok()              { 1 * f; }
+void   int_literal_div_f_ok()              { 1 / f; }
+
+// Other than int literals, type mixing requires a cast.
+void   i_eq_float_literal_disallowed()     { i = 1.0; }
+void   i_eq_f_disallowed()                 { i = f; }
+float  f_eq_i_disallowed()                 { f = i; }
+void   i_plus_float_literal_disallowed()   { i + 1.0; }
+void   i_minus_float_literal_disallowed()  { i - 1.0; }
+void   i_mul_float_literal_disallowed()    { i * 1.0; }
+void   i_div_float_literal_disallowed()    { i / 1.0; }
+void   float_literal_plus_i_disallowed()   { 1.0 + i; }
+void   float_literal_minus_i_disallowed()  { 1.0 - i; }
+void   float_literal_mul_i_disallowed()    { 1.0 * i; }
+void   float_literal_div_i_disallowed()    { 1.0 / i; }
+void   i_plus_f_disallowed()               { i + f; }
+void   i_minus_f_disallowed()              { i - f; }
+void   i_mul_f_disallowed()                { i * f; }
+void   i_div_f_disallowed()                { i / f; }
+void   f_plus_i_disallowed()               { f + i; }
+void   f_minus_i_disallowed()              { f - i; }
+void   f_mul_i_disallowed()                { f * i; }
+void   f_div_i_disallowed()                { f / i; }

tests/sksl/errors/golden/IntFloatMismatch.glsl

@@ -0,0 +1,5 @@
+### Compilation failed:
+
+error: 16: type mismatch: '=' cannot operate on 'int', 'float'
+error: 17: type mismatch: '=' cannot operate on 'int', 'float'
+2 errors