feat(codegen): support explicit template arguments

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

6 files changed, 96 insertions, 0 deletions

diff --git a/tests/i/template-explicit-args/case.json b/tests/i/template-explicit-args/case.json
new file mode 100644
index 0000000..0967ef4
--- /dev/null
+++ b/tests/i/template-explicit-args/case.json
@@ -0,0 +1 @@
+{}
diff --git a/tests/i/template-explicit-args/expected.txt b/tests/i/template-explicit-args/expected.txt
new file mode 100644
index 0000000..1c46cb5
--- /dev/null
+++ b/tests/i/template-explicit-args/expected.txt
@@ -0,0 +1,9 @@
+2.000000
+3
+tail
+0.000000
+2.500000
+9
+200
+100
+chain
diff --git a/tests/i/template-explicit-args/notes.md b/tests/i/template-explicit-args/notes.md
new file mode 100644
index 0000000..b487fdd
--- /dev/null
+++ b/tests/i/template-explicit-args/notes.md
@@ -0,0 +1,5 @@
+# template-explicit-args
+
+Human review: pending. Expected output was independently traced by AI, not captured from cpsc.
+
+Basis: TEMPLATE is a project extension. Max explicitly selects REAL and INTEGER, producing 2.000000 and 3. Second binds its first type explicitly and deduces STRING for its second, returning tail. Zero's otherwise undeducible return type is explicitly REAL, producing 0.000000. CALL and bare Print statements produce 2.500000 and 9. Pick uses the ordinary exact overload without explicit arguments (200) and the template with them (100). Echo preserves the STRING chain through a result method, and discarded STRING results exercise statement cleanup without output.
diff --git a/tests/i/template-explicit-args/program.cps b/tests/i/template-explicit-args/program.cps
new file mode 100644
index 0000000..123bda6
--- /dev/null
+++ b/tests/i/template-explicit-args/program.cps
@@ -0,0 +1,47 @@
+TEMPLATE <T>
+FUNCTION Max(A : T, B : T) RETURNS T
+    IF A > B THEN
+        RETURN A
+    ENDIF
+    RETURN B
+ENDFUNCTION
+
+TEMPLATE <A, B>
+FUNCTION Second(First : A, Last : B) RETURNS B
+    RETURN Last
+ENDFUNCTION
+
+TEMPLATE <T>
+FUNCTION Zero() RETURNS T
+    RETURN (T)0
+ENDFUNCTION
+
+TEMPLATE <T>
+PROCEDURE Print(Value : T)
+    OUTPUT Value
+ENDPROCEDURE
+
+TEMPLATE <T>
+FUNCTION Echo(Value : T) RETURNS T
+    RETURN Value
+ENDFUNCTION
+
+TEMPLATE <T>
+OVERLOAD FUNCTION Pick(Value : T) RETURNS INTEGER
+    RETURN 100
+ENDFUNCTION
+OVERLOAD FUNCTION Pick(Value : INTEGER) RETURNS INTEGER
+    RETURN 200
+ENDFUNCTION
+
+OUTPUT Max<REAL>(1.5, 2.0)
+OUTPUT Max<INTEGER>(Max<INTEGER>(1, 2), 3)
+OUTPUT Second<INTEGER>(7, "tail")
+OUTPUT Zero<REAL>()
+CALL Print<REAL>(2.5)
+Print<INTEGER>(9)
+OUTPUT Pick(7)
+OUTPUT Pick<INTEGER>(7)
+OUTPUT (STRING)Echo<STRING>("chain").C_STR()
+CALL Echo<STRING>("discarded")
+Echo<STRING>("also discarded")
diff --git a/tests/iii/template-explicit-errors/case.json b/tests/iii/template-explicit-errors/case.json
new file mode 100644
index 0000000..657f69e
--- /dev/null
+++ b/tests/iii/template-explicit-errors/case.json
@@ -0,0 +1,10 @@
+{
+  "errors": [
+    {"reason": "No matching overload for Max", "line": 19},
+    {"reason": "No matching overload for Max", "line": 20},
+    {"reason": "Explicit template arguments require a function template: Plain", "line": 21},
+    {"reason": "Explicit template arguments are not allowed on builtin EOF", "line": 22},
+    {"reason": "Explicit template arguments are not allowed on builtin MALLOC", "line": 23},
+    {"reason": "Ambiguous call to Tied", "line": 24}
+  ]
+}
diff --git a/tests/iii/template-explicit-errors/program.cps b/tests/iii/template-explicit-errors/program.cps
new file mode 100644
index 0000000..5236328
--- /dev/null
+++ b/tests/iii/template-explicit-errors/program.cps
@@ -0,0 +1,24 @@
+TEMPLATE <T>
+FUNCTION Max(A : T, B : T) RETURNS T
+    RETURN A
+ENDFUNCTION
+
+FUNCTION Plain(Value : INTEGER) RETURNS INTEGER
+    RETURN Value
+ENDFUNCTION
+
+TEMPLATE <A>
+OVERLOAD FUNCTION Tied(Value : A) RETURNS INTEGER
+    RETURN 1
+ENDFUNCTION
+TEMPLATE <B>
+OVERLOAD FUNCTION Tied(Value : B) RETURNS INTEGER
+    RETURN 2
+ENDFUNCTION
+
+OUTPUT Max<INTEGER, REAL>(1, 2)
+OUTPUT Max<REAL>(1, 2.5)
+OUTPUT Plain<INTEGER>(1)
+OUTPUT EOF<STRING>("file.txt")
+CALL MALLOC<INTEGER>(8)
+OUTPUT Tied<INTEGER>(1)