Fix handling of errors in imported modules (#387)

* Fix handling of errors in imported modules

- If a semantic error is detected in an imported module, then don't try to generate IR code for it

- Also, if a module (transitively) imports itself, then report that as an error
  - The way I'm checking for this is a bit hacky (I'm adding the module to the map of loaded modules, but in an "unfinished" state, and then using that unfinished state to detect the import of a module already being imported).

This isn't a 100% complete solution for any of the related problems, but it improves the user experience for the common case.

* Remove #import test.

The feature is slated to be removed, so it isn't worth fixing up this test case.

8 files changed, 46 insertions, 30 deletions

diff --git a/tests/bugs/import-with-error-extra.slang b/tests/bugs/import-with-error-extra.slang
new file mode 100644
index 000000000..259f6b5d1
--- /dev/null
+++ b/tests/bugs/import-with-error-extra.slang
@@ -0,0 +1,11 @@
+//TEST_IGNORE_FILE:
+
+// This file exists to be imported.
+//
+// It contains a semantic error that should lead to compilation failure
+// in the module doing the importing.
+
+void broken()
+{
+	int a = b;
+}
diff --git a/tests/bugs/import-with-error.slang b/tests/bugs/import-with-error.slang
new file mode 100644
index 000000000..f50bb1adb
--- /dev/null
+++ b/tests/bugs/import-with-error.slang
@@ -0,0 +1,11 @@
+//TEST:SIMPLE:-use-ir
+
+// Confirm that we correctly issue a diagnostic when
+// we `import` a module that has some errors in it.
+
+import import_with_error_extra;
+
+void main()
+{
+	broken();
+}
diff --git a/tests/bugs/import-with-error.slang.expected b/tests/bugs/import-with-error.slang.expected
new file mode 100644
index 000000000..b71dba0f1
--- /dev/null
+++ b/tests/bugs/import-with-error.slang.expected
@@ -0,0 +1,6 @@
+result code = -1
+standard error = {
+tests/bugs/import-with-error-extra.slang(10): error 30015: undefined identifier 'b'.
+}
+standard output = {
+}
diff --git a/tests/diagnostics/recursive-import-extra.slang b/tests/diagnostics/recursive-import-extra.slang
new file mode 100644
index 000000000..4525346fa
--- /dev/null
+++ b/tests/diagnostics/recursive-import-extra.slang
@@ -0,0 +1,6 @@
+//TEST_IGNORE_FILE:
+
+// This file creates an `import` loop with
+// `recursive-import.slang`
+
+import recursive_import;
diff --git a/tests/diagnostics/recursive-import.slang b/tests/diagnostics/recursive-import.slang
new file mode 100644
index 000000000..ff74025f8
--- /dev/null
+++ b/tests/diagnostics/recursive-import.slang
@@ -0,0 +1,6 @@
+//TEST:SIMPLE:
+
+// A file that recursively imports itself
+// (including transitive cases) should be diagnosed.
+
+import recursive_import_extra;
diff --git a/tests/diagnostics/recursive-import.slang.expected b/tests/diagnostics/recursive-import.slang.expected
new file mode 100644
index 000000000..ad5cf1975
--- /dev/null
+++ b/tests/diagnostics/recursive-import.slang.expected
@@ -0,0 +1,6 @@
+result code = -1
+standard error = {
+tests/diagnostics/recursive-import.slang(6): error 38200: module `recursive_import_extra` recursively imports itself
+}
+standard output = {
+}
diff --git a/tests/preprocessor/import.hlsl b/tests/preprocessor/import.hlsl
deleted file mode 100644
index f0618a667..000000000
--- a/tests/preprocessor/import.hlsl
+++ /dev/null
@@ -1,18 +0,0 @@
-//TEST:SIMPLE:-target none -profile vs_5_0
-
-// Confirm that `#import` interacts with preprocessor as expected
-
-// Here is a macro that flows from parent to child file
-#define FOO float
-
-// Here we import the child file
-#import "import.slang.h"
-
-// Here we use a macro that flows the other way (child->parent)
-BAR g( FOO x ) { return f(x); }
-
-// Here we confirm that importing the file again is a no-op
-#import "import.slang.h"
-
-void main()
-{}
diff --git a/tests/preprocessor/import.slang.h b/tests/preprocessor/import.slang.h
deleted file mode 100644
index a97a199f0..000000000
--- a/tests/preprocessor/import.slang.h
+++ /dev/null
@@ -1,12 +0,0 @@
-// Confirm that `#import` interacts with preprocessor as expected
-
-// We add a guard to ensure that this file isn't imported more than once
-#ifdef BAR
-#error File imported more than one!
-#endif
-
-// Here we use a macro from the parent file
-FOO f( FOO y ) { return y; }
-
-// Here is a macro that flows from child to parent
-#define BAR float