PP: Fix #1694: Rationalize errors on partially expanded macro argument.

Test/baseResults/cppBad2.vert.out

 cppBad2.vert
 ERROR: 0:3: 'macro expansion' : End of input in macro b
-ERROR: 1 compilation errors.  No code generated.
+ERROR: 0:3: '' : compilation terminated 
+ERROR: 2 compilation errors.  No code generated.
 
 
 Shader version: 100

Test/baseResults/cppBad3.vert.out

 cppBad3.vert
 ERROR: 0:3: 'macro expansion' : End of input in macro y
-ERROR: 1 compilation errors.  No code generated.
+ERROR: 0:3: '' : compilation terminated 
+ERROR: 2 compilation errors.  No code generated.
 
 
 Shader version: 100

Test/baseResults/cppBad4.vert.out

+cppBad4.vert
+ERROR: 0:4: 'macro expansion' : unexpected '#' g
+ERROR: 0:5: '' :  syntax error, unexpected SEMICOLON, expecting LEFT_PAREN
+ERROR: 2 compilation errors.  No code generated.
+
+
+Shader version: 100
+ERROR: node is still EOpNull!
+0:?   Linker Objects
+
+
+Linked vertex stage:
+
+ERROR: Linking vertex stage: Missing entry point: Each stage requires one entry point
+
+Shader version: 100
+ERROR: node is still EOpNull!
+0:?   Linker Objects
+

Test/baseResults/cppBad5.vert.out

+cppBad5.vert
+ERROR: 0:4: 'macro expansion' : End of input in macro g
+ERROR: 0:5: '' : compilation terminated 
+ERROR: 2 compilation errors.  No code generated.
+
+
+Shader version: 100
+ERROR: node is still EOpNull!
+0:?   Linker Objects
+
+
+Linked vertex stage:
+
+ERROR: Linking vertex stage: Missing entry point: Each stage requires one entry point
+
+Shader version: 100
+ERROR: node is still EOpNull!
+0:?   Linker Objects
+

Test/cppBad4.vert

+int,i=
+#define f g(#g(y
+#define g(m)
+g(f)

Test/cppBad5.vert

+int,i=
+#define f g($g(y
+#define g(m)
+g(f)

glslang/MachineIndependent/preprocessor/Pp.cpp

@@ -1027,7 +1027,9 @@ TPpContext::TokenStream* TPpContext::PrescanMacroArg(TokenStream& arg, TPpToken*
             case MacroExpandNotStarted:
                 break;
             case MacroExpandError:
-                token = EndOfInput;
+                // toss the rest of the pushed-input argument by scanning until tMarkerInput
+                while ((token = scanToken(ppToken)) != tMarkerInput::marker && token != EndOfInput)
+                    ;
                 break;
             case MacroExpandStarted:
             case MacroExpandUndef:
@@ -1039,13 +1041,10 @@ TPpContext::TokenStream* TPpContext::PrescanMacroArg(TokenStream& arg, TPpToken*
         expandedArg->putToken(token, ppToken);
     }
 
-    if (token == EndOfInput) {
+    if (token != tMarkerInput::marker) {
         // Error, or MacroExpand ate the marker, so had bad input, recover
         delete expandedArg;
         expandedArg = nullptr;
-    } else {
-        // remove the marker
-        popInput();
     }
 
     return expandedArg;
@@ -1262,7 +1261,7 @@ MacroExpandResult TPpContext::MacroExpand(TPpToken* ppToken, bool expandUndef, b
 
             if (token == ')') {
                 // closing paren of call
-                if (in->mac->args.size() == 1 && tokenRecorded == 0)
+                if (in->mac->args.size() == 1 && !tokenRecorded)
                     break;
                 arg++;
                 break;

glslang/MachineIndependent/preprocessor/PpScanner.cpp

@@ -1056,7 +1056,7 @@ int TPpContext::tokenize(TPpToken& ppToken)
         // Handle token-pasting logic
         token = tokenPaste(token, ppToken);
 
-        if (token == EndOfInput || token == tMarkerInput::marker) {
+        if (token == EndOfInput) {
             missingEndifCheck();
             return EndOfInput;
         }

gtests/AST.FromFile.cpp

@@ -97,6 +97,8 @@ INSTANTIATE_TEST_CASE_P(
         "cppBad.vert",
         "cppBad2.vert",
         "cppBad3.vert",
+        "cppBad4.vert",
+        "cppBad5.vert",
         "cppComplexExpr.vert",
         "cppDeepNest.frag",
         "cppPassMacroName.frag",