Add diagnostics for a parameter that is a function, and a mismatched #else / #endif

Closes #1169
Closes #1170

Author: hsutter

.gitignore

@@ -36,3 +36,4 @@ venv/*
 
 # VSCode workspace directory
 .vscode/
+buildh2.bat

regression-tests/test-results/msvc-2022-c++latest/MSVC-version.output

@@ -1,3 +1,3 @@
-Microsoft (R) C/C++ Optimizing Compiler Version 19.40.33811 for x64
+Microsoft (R) C/C++ Optimizing Compiler Version 19.40.33812 for x64
 Copyright (C) Microsoft Corporation.  All rights reserved.
 

source/io.h

@@ -461,20 +461,30 @@ class braces_tracker
     //  --- Preprocessor matching functions - #if/#else/#endif
 
     //  Entering an #if
-    auto found_pre_if() -> void {
-        assert(std::ssize(preprocessor) > 0);
+    auto found_pre_if(lineno_t) -> void {
         preprocessor.push_back({});
     }
 
     //  Encountered an #else
-    auto found_pre_else() -> void {
-        assert(std::ssize(preprocessor) > 1);
+    auto found_pre_else(lineno_t lineno) -> void {
+        if (std::ssize(preprocessor) < 2) {
+            errors.emplace_back(
+                lineno,
+                "#else does not match a prior #if"
+            );
+        }
+
         preprocessor.back().found_preprocessor_else();
     }
 
     //  Exiting an #endif
-    auto found_pre_endif() -> void {
-        assert(std::ssize(preprocessor) > 1);
+    auto found_pre_endif(lineno_t lineno) -> void {
+        if (std::ssize(preprocessor) < 2) {
+            errors.emplace_back(
+                lineno,
+                "#endif does not match a prior #if"
+            );
+        }
 
         //  If the #if/#else/#endif introduced the same net number of braces,
         //  then we will have recorded that number too many open braces, and
@@ -898,11 +908,11 @@ class source
             {
                 switch (pre) {
                 break;case preprocessor_conditional::pre_if:
-                    braces.found_pre_if();
+                    braces.found_pre_if( cpp2::unsafe_narrow<lineno_t>(std::ssize(lines)) );
                 break;case preprocessor_conditional::pre_else:
-                    braces.found_pre_else();
+                    braces.found_pre_else( cpp2::unsafe_narrow<lineno_t>(std::ssize(lines)) );
                 break;case preprocessor_conditional::pre_endif:
-                    braces.found_pre_endif();
+                    braces.found_pre_endif( cpp2::unsafe_narrow<lineno_t>(std::ssize(lines)) );
                 break;default:
                     assert(false);
                 }

source/parse.h

@@ -7902,6 +7902,11 @@ class parser
 
         //  And some error checks
         //
+        if (n->declaration->is_function()) {
+            error("a parameter cannot be a function", false);
+            return {};
+        }
+
         if (
             n->mod != parameter_declaration_node::modifier::none
             && !n->declaration->has_name("this")