Implement ? suffix to "quiet" a context and exclude it from backtraces (#1800)

test/asm/backtrace-depth.flags

@@ -1 +1 @@
--B 5
+-B 5 -B no-collapse

test/asm/expansion-diagnostics.flags

@@ -1 +1 @@
--B 0
+-B no-collapse

test/asm/garbage_sequence.asm

@@ -1,5 +1,5 @@
 assert 1 +# 1 == 2
-assert 2 ?<EFBFBD>* 2 == 4
-assert 3 **?<EFBFBD>?##?? 3 == 27
+assert 2 #<EFBFBD>* 2 == 4
+assert 3 **#<EFBFBD>}<EFBFBD># 3 == 27
 charmap "x", 4
 assert 4 <<#<EFBFBD>'x' == 64

test/asm/garbage_sequence.err

@@ -1,13 +1,11 @@
 error: Invalid character '#'
     at garbage_sequence.asm(1)
-error: Invalid characters '?', 0xFF (is the file UTF-8?)
+error: Invalid characters '#', 0xFF (is the file UTF-8?)
     at garbage_sequence.asm(2)
-error: Invalid characters '?', 0xFF, '?' (is the file UTF-8?)
+error: Invalid characters '#', 0xFF, '}', 0xFF (is the file UTF-8?)
     at garbage_sequence.asm(3)
 error: Invalid character '#'
     at garbage_sequence.asm(3)
-error: Invalid characters '#', '?', '?'
-    at garbage_sequence.asm(3)
 error: Invalid characters '#', 0xFF (is the file UTF-8?)
     at garbage_sequence.asm(5)
-Assembly aborted with 6 errors!
+Assembly aborted with 5 errors!

test/asm/lex-label.err

@@ -1,10 +1,10 @@
 error: syntax error, unexpected label, expecting symbol
     at lex-label.asm(1)
-error: syntax error, unexpected label, expecting symbol
+error: syntax error, unexpected label, expecting ? or symbol
     at lex-label.asm(3)
 error: syntax error, unexpected ENDM
     at lex-label.asm(4)
-error: syntax error, unexpected label, expecting symbol
+error: syntax error, unexpected label, expecting ? or symbol
     at lex-label.asm(6)
 error: syntax error, unexpected ENDR
     at lex-label.asm(7)

test/asm/loud-backtrace.asm

@@ -0,0 +1,20 @@
+macro mac
+	warn "from macro"
+endm
+mac ; normal
+
+macro? quiet
+	warn "from quiet macro"
+endm
+quiet
+rept? 1
+	warn "from quiet rept"
+endr
+for? x, 1
+	warn "from quiet for (x={d:x})"
+endr
+include? "loud-backtrace.inc"
+macro loud
+	warn "from loud macro"
+endm
+mac?

test/asm/loud-backtrace.err

@@ -0,0 +1,12 @@
+warning: from macro [-Wuser]
+    at loud-backtrace.asm::mac(2) <- loud-backtrace.asm(4)
+warning: from quiet macro [-Wuser]
+    at loud-backtrace.asm::quiet(7) <- loud-backtrace.asm(9)
+warning: from quiet rept [-Wuser]
+    at loud-backtrace.asm::REPT~1(11) <- loud-backtrace.asm(10)
+warning: from quiet for (x=0) [-Wuser]
+    at loud-backtrace.asm::REPT~1(14) <- loud-backtrace.asm(13)
+warning: from quiet include [-Wuser]
+    at loud-backtrace.inc(1) <- loud-backtrace.asm(16)
+warning: from macro [-Wuser]
+    at loud-backtrace.asm::mac(2) <- loud-backtrace.asm(20)

test/asm/loud-backtrace.flags

@@ -0,0 +1 @@
+-B all

test/asm/loud-backtrace.inc

@@ -0,0 +1 @@
+warn "from quiet include"

test/asm/quiet-backtrace.asm

@@ -0,0 +1,20 @@
+macro mac
+	warn "from macro"
+endm
+mac ; normal
+
+macro? quiet
+	warn "from quiet macro"
+endm
+quiet
+rept? 1
+	warn "from quiet rept"
+endr
+for? x, 1
+	warn "from quiet for (x={d:x})"
+endr
+include? "quiet-backtrace.inc"
+macro loud
+	warn "from loud macro"
+endm
+mac?

test/asm/quiet-backtrace.err

@@ -0,0 +1,12 @@
+warning: from macro [-Wuser]
+    at quiet-backtrace.asm::mac(2) <- quiet-backtrace.asm(4)
+warning: from quiet macro [-Wuser]
+    at quiet-backtrace.asm(9)
+warning: from quiet rept [-Wuser]
+    at quiet-backtrace.asm(11)
+warning: from quiet for (x=0) [-Wuser]
+    at quiet-backtrace.asm(14)
+warning: from quiet include [-Wuser]
+    at quiet-backtrace.asm(16)
+warning: from macro [-Wuser]
+    at quiet-backtrace.asm(20)

test/asm/quiet-backtrace.inc

@@ -0,0 +1 @@
+warn "from quiet include"

test/asm/rept-macro-fstack-trace.flags

@@ -1 +1 @@
--B 0
+-B no-collapse