More preprocessor issues including an infinite loop (#1791)

* #include an absolute path didn't work - because paths were taken to always be relative.

* Tests showing issues with preprocessor behavior.

* Fix comment/typo.

* Infinite loop.

* Another preproc bug.

* Small fixes in preproc test

* Bug around empty single parameter

* Repeated parameter name.

* Fix comment.

* #undef of undefined macro is not an error.

* Clarify that it is a warning on Slang.

* Fix expected diagnostic.

* Fix preproc-detail-2.slang.expected

10 files changed, 89 insertions, 8 deletions

diff --git a/tests/current-bugs/preproc-concat-4.slang b/tests/current-bugs/preproc-concat-4.slang
index 47b0e1452..31ec16268 100644
--- a/tests/current-bugs/preproc-concat-4.slang
+++ b/tests/current-bugs/preproc-concat-4.slang
@@ -2,13 +2,6 @@
 
 // NOTE! This test should *fail*, if preprocessor is working correctly!
 
-// So the real question here is what happens with pasting and stringifying. 
-// As per the spec they have to be performed *before* expansion. If when we do an expansion
-// we add to the stream FunctionArg that holds the 'to be' lazily expanded parameter we have a problem
-//
-// If we move to a new stream *and* the token afterwards, is ## 
-
-
 #define CONCAT(a, b) a ## b
 
 #define A a
@@ -21,7 +14,7 @@
 
 // Should be 
 // CONCAT(a, b) A2B2 CONCAT(a, b)
-// CONCAT is disabled, A2 and B2 are processed on next pass
+// CONCAT is disabled, A and B are expanded on next pass
 // A2 B2 are first and last tokens pre expansion args
 // 
 // Slang outputs 
diff --git a/tests/current-bugs/preproc-concat-5.slang b/tests/current-bugs/preproc-concat-5.slang
new file mode 100644
index 000000000..2be554f89
--- /dev/null
+++ b/tests/current-bugs/preproc-concat-5.slang
@@ -0,0 +1,13 @@
+//DISABLE_DIAGNOSTIC_TEST:SIMPLE:-E
+
+// NOTE! This test should *fail*, if preprocessor is working correctly!
+
+// It should produce 'THING', as the original invocation should have disabled THING, 
+// but it actually ends up in an infinite loop.
+
+#define CONCAT(x, y) x ## y
+
+#define THING2 THING
+#define THING CONCAT(THING, 2)
+
+THING
diff --git a/tests/current-bugs/preproc-detail-1.slang b/tests/current-bugs/preproc-detail-1.slang
new file mode 100644
index 000000000..4cff0d205
--- /dev/null
+++ b/tests/current-bugs/preproc-detail-1.slang
@@ -0,0 +1,12 @@
+//DIAGNOSTIC_TEST:SIMPLE:-E
+
+// NOTE! This test should *fail*, if preprocessor is working correctly!
+
+// If a macro can take a single parameter, it is valid to pass in 'nothing'.
+// Slang outputs an error about the wrong amount of parameters
+// Correct output: a b
+
+#define A(x) a x b
+
+A()
+
diff --git a/tests/current-bugs/preproc-detail-1.slang.expected b/tests/current-bugs/preproc-detail-1.slang.expected
new file mode 100644
index 000000000..ba93983af
--- /dev/null
+++ b/tests/current-bugs/preproc-detail-1.slang.expected
@@ -0,0 +1,7 @@
+result code = 0
+standard error = {
+tests/current-bugs/preproc-detail-1.slang(10): error 15501: wrong number of arguments to macro (expected 1, got 0)
+}
+standard output = {
+
+}
diff --git a/tests/current-bugs/preproc-detail-2.slang b/tests/current-bugs/preproc-detail-2.slang
new file mode 100644
index 000000000..eb687db31
--- /dev/null
+++ b/tests/current-bugs/preproc-detail-2.slang
@@ -0,0 +1,10 @@
+//DIAGNOSTIC_TEST:SIMPLE:-E
+
+// NOTE! This test should *fail*, if preprocessor is working correctly!
+
+// Macro parameters must have unique names
+
+#define A(x, x) a x b x c
+
+A(,)
+
diff --git a/tests/current-bugs/preproc-detail-2.slang.expected b/tests/current-bugs/preproc-detail-2.slang.expected
new file mode 100644
index 000000000..b48d7909f
--- /dev/null
+++ b/tests/current-bugs/preproc-detail-2.slang.expected
@@ -0,0 +1,6 @@
+result code = 0
+standard error = {
+}
+standard output = {
+a b c 
+}
diff --git a/tests/current-bugs/preproc-detail-3.slang b/tests/current-bugs/preproc-detail-3.slang
new file mode 100644
index 000000000..b0675204b
--- /dev/null
+++ b/tests/current-bugs/preproc-detail-3.slang
@@ -0,0 +1,9 @@
+//DIAGNOSTIC_TEST:SIMPLE:-E
+
+// NOTE! This test should *fail*, if preprocessor is working correctly!
+
+// Undefining a macro that is not defined within C/C++ is defined as *not* an error or a warning.
+// On checking with DXC/FXC they also have this behavior (ie they don't output anything)
+// It's arguable if Slang should match this behavior - at least it is a warning.
+
+#undef C
\ No newline at end of file
diff --git a/tests/current-bugs/preproc-detail-3.slang.expected b/tests/current-bugs/preproc-detail-3.slang.expected
new file mode 100644
index 000000000..a44c60220
--- /dev/null
+++ b/tests/current-bugs/preproc-detail-3.slang.expected
@@ -0,0 +1,9 @@
+result code = 0
+standard error = {
+tests/current-bugs/preproc-detail-3.slang(9): warning 15401: macro 'C' is not defined
+#undef C
+       ^
+}
+standard output = {
+
+}
diff --git a/tests/current-bugs/preproc-expand-1.slang b/tests/current-bugs/preproc-expand-1.slang
new file mode 100644
index 000000000..f95b432e2
--- /dev/null
+++ b/tests/current-bugs/preproc-expand-1.slang
@@ -0,0 +1,16 @@
+//DIAGNOSTIC_TEST:SIMPLE:-E
+
+// NOTE! This test should *fail*, if preprocessor is working correctly!
+
+// Should produce: Hi
+// Slang produces: C ( Hi ) 
+
+#define OPEN (
+#define CLOSE )
+
+#define C(x) x
+
+#define B(x) x
+
+B(C OPEN Hi CLOSE)
+
diff --git a/tests/current-bugs/preproc-expand-1.slang.expected b/tests/current-bugs/preproc-expand-1.slang.expected
new file mode 100644
index 000000000..d46fa1159
--- /dev/null
+++ b/tests/current-bugs/preproc-expand-1.slang.expected
@@ -0,0 +1,6 @@
+result code = 0
+standard error = {
+}
+standard output = {
+C ( Hi ) 
+}