Support testing error cases in our SkSL unit test goldens.

Change-Id: I56e19153597e2c4393c5821314b82937828c0d50
Bug: skia:10694
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/316569
Commit-Queue: John Stiles <johnstiles@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
Auto-Submit: John Stiles <johnstiles@google.com>

gn/compile_sksl_tests.py

@@ -9,29 +9,50 @@ import os
 import subprocess
 import sys
 
+def unlinkIfExists(path):
+    try:
+        os.unlink(path)
+    except OSError:
+        pass
+
+def compile(skslc, input, target, extension):
+    target += extension
+    try:
+        subprocess.check_output([skslc, input, target], stderr=subprocess.STDOUT)
+        return True
+
+    except subprocess.CalledProcessError as err:
+        with open(target, 'wb') as dst:
+            dst.write("### Compilation failed:\n\n")
+            dst.write(err.output)
+        return False
+
 skslc = sys.argv[1]
 inputs = sys.argv[2:]
 
 for input in inputs:
-    try:
-        noExt, ext = os.path.splitext(input)
-        head, tail = os.path.split(noExt)
-        targetDir = os.path.join(head, "golden")
-        if not os.path.isdir(targetDir):
-            os.mkdir(targetDir)
-        target = os.path.join(targetDir, tail)
-        if ext == ".fp":
-            subprocess.check_output([skslc, input, target + ".h"],
-                                    stderr=subprocess.STDOUT)
-            subprocess.check_output([skslc, input, target + ".cpp"],
-                                    stderr=subprocess.STDOUT)
-        elif ext == ".sksl":
-            subprocess.check_output([skslc, input, target + ".glsl"],
-                                    stderr=subprocess.STDOUT)
+    noExt, ext = os.path.splitext(input)
+    head, tail = os.path.split(noExt)
+    targetDir = os.path.join(head, "golden")
+    if not os.path.isdir(targetDir):
+        os.mkdir(targetDir)
+    target = os.path.join(targetDir, tail)
+    if ext == ".fp":
+        # First, compile the CPP. If we get an error, stop here.
+        if compile(skslc, input, target, ".cpp"):
+            # Next, compile the header.
+            if compile(skslc, input, target, ".h"):
+                # Both files built successfully.
+                continue
+            else:
+                # The header generated an error; this counts as an overall failure for this test.
+                # Remove the passing CPP output since it's not relevant in a failure case.
+                unlinkIfExists(target + ".cpp")
         else:
-            print("### Unrecognized file type for " + input + ", skipped")
-
-    except subprocess.CalledProcessError as err:
-        print("### Error compiling " + input + ":")
-        print(err.output)
-        exit(1)
+            # The CPP generated an error. We didn't actually generate a header, but there might be
+            # one from prior runs. Let's remove it for clarity.
+            unlinkIfExists(target + ".h")
+    elif ext == ".sksl":
+        compile(skslc, input, target, ".glsl")
+    else:
+        print("### Unrecognized file type for " + input + ", skipped")

gn/sksl_tests.gni

@@ -6,6 +6,13 @@
 # Things are easiest for everyone if these source paths are absolute.
 _tests = get_path_info("../tests", "abspath")
 
-sksl_fp_tests_sources = [ "$_tests/sksl/fp/GrHelloWorld.fp" ]
+sksl_fp_tests_sources = [
+  "$_tests/sksl/errors/GrBothExplicitReturnAndSkOutColor.fp",
+  "$_tests/sksl/fp/GrHelloWorld.fp",
+]
 
-sksl_glsl_tests_sources = [ "$_tests/sksl/glsl/HelloWorld.sksl" ]
+sksl_glsl_tests_sources = [
+  "$_tests/sksl/errors/OpenArray.sksl",
+  "$_tests/sksl/errors/UndefinedSymbol.sksl",
+  "$_tests/sksl/glsl/HelloWorld.sksl",
+]

tests/sksl/errors/GrBothExplicitReturnAndSkOutColor.fp

@@ -0,0 +1,4 @@
+half4 main() {
+    sk_OutColor = half4(1, 0, 1, 0);
+    return half4(0, 1, 0, 1);
+}

tests/sksl/errors/OpenArray.sksl

@@ -0,0 +1 @@
+void main(inout float4 color) { color.r[ = ( color.g ); }

tests/sksl/errors/UndefinedSymbol.sksl

@@ -0,0 +1 @@
+void main() { x = float2(1); }

tests/sksl/errors/golden/GrBothExplicitReturnAndSkOutColor.cpp

@@ -0,0 +1,5 @@
+### Compilation failed:
+
+error: 3: Fragment processors must not mix sk_OutColor and return statements
+
+1 error

tests/sksl/errors/golden/OpenArray.glsl

@@ -0,0 +1,4 @@
+### Compilation failed:
+
+error: 1: expected expression, but found '='
+1 error

tests/sksl/errors/golden/UndefinedSymbol.glsl

@@ -0,0 +1,4 @@
+### Compilation failed:
+
+error: 1: unknown identifier 'x'
+1 error